research on nuclear energy

News from the Columbia Climate School

The State of Nuclear Energy Today — and What Lies Ahead

President-elect Joe Biden comes into office at a time when phasing out fossil fuels is critical. The Intergovernmental Panel on Climate Change (IPCC) has warned that we must keep the planet from warming more than 1.5˚C above pre-industrial levels by 2030. Every pathway the IPCC envisioned to achieve this goal requires an increase in nuclear energy—of 59 to 106 percent more than 2010 levels by 2030. Biden’s $2 trillion climate plan , recognizing this urgency, includes support for the development of nuclear energy. What is the current state of nuclear energy in the U.S., and what role could it play in a decarbonized future?

Nuclear energy’s role in fighting climate change

Nuclear power is the second largest source of clean energy after hydropower. The energy to mine and refine the uranium that fuels nuclear power and manufacture the concrete and metal to build nuclear power plants is usually supplied by fossil fuels, resulting in CO2 emissions; however, nuclear plants do not emit any CO2 or air pollution as they operate. And despite their fossil fuel consumption, their carbon footprints are almost as low as those of renewable energy. One study  calculated that a kilowatt hour of nuclear-generated electricity has a carbon footprint of 4 grams of CO2 equivalent, compared to 4 grams for wind and 6 grams for solar energy — versus 109 grams for coal, even with carbon capture and storage.

In the last 50 years, nuclear energy has precluded the creation of 60 gigatons of carbon dioxide, according to the International Energy Agency. Without nuclear energy, the power it generated would have been supplied by fossil fuels, which would have increased carbon emissions and resulted in air pollution that could have caused millions more deaths each year.

The state of nuclear energy today

Around the world, 440 nuclear reactors currently provide over 10 percent of global electricity. In the U.S., nuclear power plants have generated almost 20 percent of electricity for the last 20 years.

Most of the nuclear plants operating today were designed to last 25 to 40 years and with an average age of 35 years, a quarter of them in developed countries will likely be shut down by 2025. After the Fukushima meltdown, a number of countries began to consider phasing out their nuclear programs, with Germany expected to shut down its entire nuclear fleet by 2022.

The U.S. has 95 nuclear reactors in operation, but only one new reactor has started up in the last 20 years. Over 100 new nuclear reactors are being planned in other countries, and 300 more are proposed, with China, India, and Russia leading the way.

How nuclear reactors work

All commercial reactors generate heat through nuclear fission, wherein the nucleus of a uranium atom is split into smaller atoms (called the fission products). The splitting releases neutrons that trigger a chain reaction in other uranium atoms.

As the atoms split, they release a tremendous amount of energy—a kilogram of uranium undergoing fission releases three million times more energy than a kilogram of coal being burned. Coolant, often water, circulates around the reactor core to absorb the heat that fission creates; the heat boils the water, creating pressurized steam to turn a turbine and generate electricity.

Reactor fuel is usually uranium in pellets that are placed in fuel rods and arranged in the reactor’s core. A 1,000MW nuclear reactor might contain as many as 51,000 rods with over 18 million pellets.

After it fuels the reactor for four to six years, the spent fuel is replaced with new fuel rods. The highly radioactive and hot spent fuel rods are transferred to a pool of water on-site that cools and shields them.

After about five years, when enough of the energy has decayed, the fuel is transferred to dry casks that are stored on-site in concrete bunkers. This is how most of the nuclear waste that has been produced over the years is currently stored.

The challenges facing nuclear energy

The nuclear industry in the U.S. faces resistance due to a number of factors.

Nuclear accidents

The American public has misgivings about nuclear power because of three nuclear accidents that occurred: the Three Mile Island partial meltdown in 1979, the Chernobyl meltdown and explosion in 1986, and the Fukushima meltdown in 2011 precipitated by an earthquake and a tsunami.

Both the Three Mile Island and Fukushima accidents began after the reactors were shut down and a lack of power prevented the pumps from circulating water to cool the decaying fuel. Similar light water reactors, cooled with ordinary water, make up the majority of the nuclear reactors in use.

While nuclear accidents are rare, the consequences are catastrophic. Fukushima’s meltdown drove over 200,000 people from their homes. Chernobyl’s reactor site will be radioactive for tens of thousands of years.

Nuclear proliferation

The uranium found in nature consists of mostly uranium-238, and a tiny amount of uranium-235, which is what is needed for fission. The process of concentrating and increasing the U-235 in relation to U-238 is called enrichment. However, enrichment is controversial because the process can sometimes be used to create uranium for nuclear weapons, as can reprocessing spent fuel to recover uranium and plutonium to recycle them for fresh fuel.

“The U.S. position since the Ford administration has been to not reprocess fuel, because we don’t really want other countries reprocessing their fuel,” said Matt Bowen, a research scholar focusing on nuclear energy at Columbia University’s Center on Global Energy Policy.

To prevent nuclear proliferation, most countries have signed onto international agreements to limit nuclear weapons, and the International Atomic Energy Agency regularly inspects nuclear facilities to monitor their nuclear materials.

Nuclear waste

There is still no viable way to permanently dispose of the radioactive material that is produced at every stage of a nuclear power plant’s life, from the mining and enrichment of uranium through operation to the spent fuel. Of this radioactive material, three percent—mostly spent fuel—is considered high-level waste, meaning that it is extremely dangerous and will be radioactive for tens of thousands of years; it needs to be cooled, then safely contained virtually forever. Seven percent is intermediate waste, material from the reactor’s core and other reactor parts; this is also dangerous but can be contained in canisters. The rest, made up of building materials, plastics and other miscellany, is considered low-level waste, but also needs to be stored.

A Greenpeace report estimates that there are 250,000 tons of high-level waste in 14 countries that are sitting in temporary storage. The U.S. itself has almost 90,000 tons of high-level waste awaiting permanent disposal. While governments and industry agree that deep burial is the best solution for nuclear waste, no country has a site for deep burial in operation. One nuclear expert said  that “there is no scientifically proven way” of disposing of high- and intermediate- level waste.

In 1987, Yucca Mountain in Nevada was selected to be a disposal site for U.S. nuclear waste, but it has been opposed by state leaders and residents, and its fate is in limbo.

New nuclear reactors can cost over $7 billion, which makes them expensive propositions, especially when natural gas is so cheap. Some of the newest nuclear projects have gone far over schedule and over budget. Bowen said that Westinghouse’s failure to build two of four new-and-improved AP1000 reactors planned for South Carolina and Georgia has had serious consequences for the whole nuclear industry. After costing $9 billion dollars, the two South Carolina reactors were canceled. “It’s not the materials that are resulting in the high costs, but a doubling of the construction time,” he said. “For the AP1000s, it is widely acknowledged that the construction was begun at a relatively low design maturity. It’s not that Westinghouse wasn’t completely aware that they were beginning construction before they finished the design, and [that] there was some risk involved. They just didn’t think it would go as badly as it went.”

Bowen added that he thinks the cancellation of South Carolina’s AP1000s is “the shadow that’s cast over the whole U.S. industry. It took down a utility—which should make other utilities more cautious about building a first-of-a-kind nuclear reactor.”

The Georgia reactors, also late and over budget, are scheduled to begin operation in 2021 and 2022.

The evolution of nuclear reactors

The first generation of nuclear reactors was developed in the 1950s; by 2015, these had all shut down. Generation II reactors are the ones mostly in operation today. While they were designed to last only 40 years, as of 2018, the Nuclear Regulatory Agency had granted license renewals to 89 reactors for an additional 20 years. (Three of those reactors have since shut down.) A few plants have been relicensed out to 80 years. Relicensing usually involves upgrading or replacing old equipment and technology, and is less costly than constructing a brand-new reactor.

Advanced reactors, sometimes called  Generation III and III+,  are operating in Japan and being built in other countries. Generation IV reactors are still in the design stage.

Many of the new nuclear plant designs that are in advanced planning stages, under construction, or being researched in North America, Europe, Japan, Russia and China address the main challenges of nuclear energy. They incorporate improvements in safety and cost, as well as in reliability, proliferation resistance and waste reduction.

Whereas traditional reactors depended on mechanical systems to deal with malfunctions, many new reactors utilize passive safety measures that don’t need outside operators. This entails systems that rely on gravity, convection or tolerance of high temperatures to prevent accidents. Some are designed more simply, which means there are fewer components that can malfunction. Others have a more standardized design so that modular components, which can be manufactured in a factory, can be used, reducing construction time and costs; older nuclear reactors usually had to be fabricated on-site. Many new reactors also use fuel more efficiently and produce less waste, and some are designed to consume nuclear waste as fuel.

Some new reactors

Here are just a few of the many new reactors being planned with a variety of technologies and designs. The first two listed were chosen by the Department of Energy’s (DOE) Advanced Reactor Demonstration Program. They each will receive $80 million this year and an additional $400 million to $4 billion over the next five to seven years. The DOE also plans to make two to five more awards totaling $30 million for advanced reactor designs by December.

TerraPower , co-founded by Bill Gates, and GE Hitachi Nuclear Energy are developing a 345MW Natrium reactor that will use molten sodium metal as a coolant. Sodium has a much higher boiling point than water so the coolant would not need to be pressurized, making operation simpler. Moreover, it saves on costs because there is no need to construct a large containment structure. The heat in the sodium will be transferred to molten salt, to either drive a steam turbine or be stored for later use. This allows the system to boost its output to 500MW for over five and a half hours if necessary. The Natrium will also use more highly enriched uranium, which would enable it to burn fuel more efficiently. The Natrium reactor is expected to be operational in the late 2020s.

The 80MW high temperature reactor , Xe-100 , developed by X-Energy, uses fuel in pebble form, which cannot melt down. The 220,000 balls of graphite filled with ceramic uranium-filled kernels slowly make their way down through the core and exit out the bottom when they are spent. They are cooled by pressurized helium, which heats up to 750˚C to produce steam for electricity. The reactor’s simpler design uses components that can be manufactured in a factory then assembled, and due to its modular design, it can be combined with other 80MW reactors to produce 320MW or more. Bowen noted that the higher efficiency of this reactor means it can produce a smaller amount of waste per megawatt-hour generated.

Terrapower’s traveling wave reactor  is a liquid sodium cooled reactor operating at atmospheric pressure. It uses fuel made from depleted uranium, a byproduct of the fuel enrichment process that is often disposed of. The used fuel is kept in the core so there is no need for storage. Terrapower claims that the traveling wave reactor will eventually eliminate enrichment and reprocessing, thus reducing proliferation risk. Over its 60-year lifetime, the total amount of waste it produces would fill only one and a half rail cars. With the design almost complete and engineering begun, it’s expected to begin operation in the mid-2020s.

NuScale  is developing a small modular light water reactor that will generate 77MW. It will occupy the space of only one percent of a conventional reactor. The design has been simplified to eliminate pumps and other moving parts, which makes it safer, and the reactor can shut itself down and cool itself without any need for an outside operator. Its compact size enables it to be used for communities that need less power as well as for medical and military installations. Twelve small modular reactors could be placed together to form a 924MW power plant, with some modules producing electricity while others provide heat for industry. The Department of Energy has partnered with NuScale and Utah Associated Municipal Power Systems to develop this reactor, but recently eight of the 36 utilities involved backed out. Nevertheless, NuScale is scheduled to bring the first module online by mid-2029 and the remaining 11 modules by 2030 to align with when UAMPS’ coal-fired plants retire, according to NuScale’s Diane Hughes. The total budget is projected to be $6.1 billion.

There are many designs of fast neutron reactors in development with sodium, lead, gas, and molten salt coolants. Because these coolants enable neutrons to move faster than water does, fast reactors have the potential to yield 60 times more energy from uranium than traditional light water reactors. In any reactor, some of the U-238 is turned into different forms of plutonium during its operation, and some then undergo fission to produce heat. Fast neutron reactors can optimize this process so that it actually “breeds” more fuel. While fast reactors have been around since the 1950s, there is more interest in them today because of the pileup of nuclear waste, and the ability of these reactors to destroy through fission the elements in spent fuel that make it highly radioactive for so long—instead of the waste being toxic for tens of thousands of years, it is toxic for a hundred years.

Microreactors  that can fit in the back of a semi-truck could produce from one to 20MW of power and be used for heat or electricity. Their small size makes them able to generate energy for industrial processes along with heating and cooling in remote areas, natural disaster areas, and military bases around the world; in addition they can be easily integrated with renewable energy in microgrids. Oklo Power is developing its Aurora micro modular fast reactor , which will deliver 1.5MW of power and heat at Idaho National Laboratory. The compact design incorporates solar panels, and will use a new kind of “high-assay, low-enriched uranium” fuel called HALEU. This means the uranium is enriched to have a higher concentration of the U-235 needed for fission, which allows the reactor to get more power from the fuel and be refueled less often. HALEU isn’t yet commercially available.

Other uses for nuclear energy

Nuclear energy will need to play a key role in decarbonizing the economy because it is difficult for renewable energy to muster the intense heat needed in industrial processes, such as steel and cement production. These kinds of industrial processes comprise 10 percent of global emissions, according to Columbia University’s Center on Global Energy Policy. Some advanced reactors, such as the high-temperature gas-cooled reactor, can provide both electricity and heat for petroleum refining, or for the production of fertilizer and chemicals. Nuclear reactors could also be used to produce the electricity needed to split water into hydrogen and oxygen; clean hydrogen could then be used to generate heat for steel manufacturing and other industrial activities, to fuel vehicles, produce synthetic fuel, or store energy for the grid.

Most desalination plants that convert seawater into drinking water require a great deal of energy that usually comes from fossil fuels. Small modular reactors located by the ocean could generate the electricity needed for desalination.

The prospects for nuclear energy

Biden’s climate plan supports research into “affordable, game-changing technologies to help America achieve our 100 percent clean energy target,” with a focus on small modular reactors and the issues that challenge nuclear energy development: cost, safety and waste disposal. Biden could potentially get Republican buy-in for climate legislation through nuclear energy, since nuclear energy bills have received bipartisan support in the past. Since 2018, two acts that would speed the modernization of the Nuclear Regulatory Commission, support the development of advanced reactor fuel, and help nuclear developers collaborate with universities and the national labs, received bipartisan support in Congress and were signed into law. The bipartisan Nuclear Energy Leadership Act introduced in 2019 would help advanced nuclear reactor concepts go from research to commercialization by matching private capital to build two demo reactors by 2025 and potentially five more by 2035.  The Nuclear Waste Administration Act of 2019 was introduced by a bipartisan group of senators to create a new entity to focus on nuclear waste management.

“It makes sense from a risk management point of view to have investments in nuclear be part of the solution [to climate change],” said Bowen. “But the generation that we’re talking about is going to need years to sort of mature and they will still have to build their first unit relatively close to on time and on budget. Otherwise, there isn’t going to be a second unit.” And despite the Congressional acts and the many plans for new reactors, he thinks we may not see many new reactors in the U.S. unless Congress passes a federal clean energy standard. Bowen believes relicensing may actually be the key to more nuclear energy. “I have more confidence that there will be measures to maintain the existing fleet, which is just a much lighter lift,” he said. “I’m optimistic that there’s going to be more and more of the subsequent relicensing where we’re extending the plant operations from 60 to 80 years.”

As for new reactors, Nuscale’s small modular reactors are farthest along and won’t be operating until 2030 at this point. But if the company can successfully bring the project in reasonably on time, and if there is a national climate policy driving us to zero carbon emissions, Bowen thinks more nuclear power plants could get built to substantially support the decarbonization of the electric grid by the 2050s.

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https://en.wikipedia.org/wiki/Nuclear_reprocessing#:~:text=On%207%20April%201977%2C%20President%20Jimmy%20Carter%20banned,encourage%20other%20nations%20to%20follow%20the%20USA%20lead .

Why dont we reprocess https://youtu.be/5t-j8pVsnc0

This article is 0 for 3 on the subjects of accidents, proliferation and waste.

The effects of even worst-case nuclear accidents are NOT catastrophic! TMI had no affect at all (other than loss of plant). Chernobyl is simply not applicable to the risks of modern nuclear power. Fukushima, the only significant release of pollution in non-Soviet nuclear power’s entire history caused (and will cause) few if any deaths and will never have any measurable public health impact. Meanwhile, pollution from fossil power generation causes ~1000 deaths every single day, along with global warming. Thus, fossil generations’ *daily* impact is far worse than the “catastrophic” impact of a worst-case meltdown.

The long-term evacuations at Fukushima were not justified. No areas around Fukushima were as unhealth a place to live as most of the world’s large cities. Almost all of the “impacts” on people’s lives are not from nuclear accidents themselves, but unjustified *over-reactions* to them.

Nuclear power simply does not have a significant impact on weapons proliferation. In particular, adding more nuclear plants in countries that already have nuclear power, or the bomb, as zero proliferation impact. As long as developing nations do not employ enrichment or reprocessing facilities, the proliferation impacts of nuclear power, worldwide, will be negligible. And there is no real need for enrichment or reprocessing facilities in such nations.

The discussion of nuclear waste is the worst of all. Literally the opposite of the truth. Not only has the waste “problem” been technically solved for a long time, but nuclear is the ONLY energy source that has a technically viable plan to contain its wastes for as long as they remain hazardous. NRC has concluded that Yucca Mtn. would meet that impeccable, un precedented requirements. Other repositories (in Finland, etc.) have been approved and are moving forward. Unlike the waste streams and pollution from other energy sources, nuclear waste has never harmed anyone, and almost certainly never will.

The toxic waste streams from other energy sources and industries are many orders of magnitude larger in volume, are in a much harder to contain physical/chemical form (compared to nuclear waste which is in the form of ceramic pellets inside corrosion-resistant metal rods), actually last *longer* than nuclear waste (forever, vs. decaying away exponentially) and are disposed of with infinitely less care. Non-nuclear toxic waste streams are simply shallow-buried or are released directly into the environment. For all these reasons, the waste streams from other energy sources pose a far *larger* long-term hazard than nuclear wastes.

Nuclear’s only real problem is cost, but that is largely a symptom of the extreme over-reaction to the three “problems” listed above.

Nuclear is not lacking in technical merit. We don’t need advanced reactors or fuel cycles to solve those hyped to non-existent “problems”. Nuclear already is the safest and lowest environmental / public health impact source. Nuclear’s high costs are also not due to lack of technical merit, but are instead due to double standards and unlevel policy and regulatory playing fields. Regulatory reform and technology-neutral climate policies (such as carbon pricing) can’t come soon enough.

Ask any 10 people if they are in favor of Nuclear power and the large majority will say no. The biggest hurdles for Nuclear power are not technical but overcoming stupidity.

It is the human element, not ignorance, but zealots with advanced technical abilities with a desire to burn the planet. Eliminate that element – oh, wait, that goes back to sentence number one. Further, your individual assessment of the environmental impacts of Fukushima and Chernobyl are not at all correct. TMI, yeah, we got REALLY LUCKY. After all that being said, I don’t know that we eventyually will not have any other options.

You are right and , thus, along with the “smart folks” in our minority. In fact, by the time most Americans and Europens find out-, the news of Chernobyl: that it was not the nationwide disaster nor did it cause mass die offs of animals or people. . People, being greedy, will hopefully-(probably) have returned to area that was marked off as permanently poisoned. In fact, the animals have returned and none are having moter or deformed offspring. Chernobyl will be a new eden for the animals and people ewho ignore the alleged “threats” of nuclear radiation. In fact, humans and animals have lived with and as a consequence of the earth’s nuclear radiation since the beginning of life-As the half life of rqadioactive materials was earten away, the living things both in the oceans and on land, learned to develop in the presence of radiation. The one example no one ever looks at is France. In 1976, France, also seriously affected by the oil shock, and having no oil or gas & coal of its own, decided to push ahead with a national “fleet” of atomic fission (nuclear) plants. Within 20 years-by 19995, France became the first and only,(so far), nation to run it’s entire electrical “grid” and system, off of it’s nuclear power reactors. Since then, because the “Green” party(s) are so powerful in Western Europe- many solar and wind farms were constructed to show the world that aside from developing the first home computer, first internet-WWWeb,(the Minitel), and the first absolte zero emission electricity and power generation system, that France could also bild (un needed), Green or free solar and wind power. The only rsult has been that the nuclear powr reactors now no longer need to to run all the time, but to prove to other Green Party advocates-and anti nuclear ignoramuses, that G+France could also do the “stupid” and build highly toxic, poorly thought out solar farms that are filled with toxic parts which are expensive to deconstruct-being all but impossible to bury, needing very expensive decommissioning. This is similarly so for when the enormous blades of wind turbines have to cut up. There is no place to bury them. The change will be expensive but humans have lived with radiation since long before we had written language-long before we could talk-and when we shared the planet with numerous other groups of intelligent hominims. If we don’t ALL make the switch (kind of a world wide kicking of the cigarette & tobacco habit)- we will all watch as we all die, with a few, like Elon Musk, trying to build a billionaire’s outpost-much like “Farham’s Freehold”, surrounded by patrol boats and armed on one of the Hawaiian islands, to prevent the ingress of non wealthy, non white Europeans, like Australia and , similar to Japan’s treatment of castaway sailors in the era before the end of the Tokugawa shogunate-Musk may also order the foreigners either enslaved, or used as food or fishbait. Australia is doing pretty much the same thing with anyone trying to enter their version of “South African minority” heaven. Our one , “common” to all way out of this deadly “maze of death” is to build lots of standardized, nuclear reactors so we have enough power to begin decarbonizing the atmosphere. The concept of de-carbonizing oil. gas or coal is an unworkable idea-it won’t work and, allows for driller/pipeline owners to fake results, both by emptying gas into the air-or, simply pretending to remove carbon-do you know if you can tell if billions of cubic ft of gas in a pipe has been stripped of C12? I can’t-So I turned off my gas and use a microwave. Our companies selling hydrocarbons are not trustworthy. We need more nuclear and we need to build it now-even if we claim we can’t afford it-as our kids and grand-kids will kills us before they die from our greed and thoughtlessness. We’ll have deserved a painful and miserable death-like the Terror, in revolutionary France,(they also gave the world the first planetary style dictator!).

Nuclear energy is going to play a big role in reversing climate change, given its net-negative carbon footprint.

Yes, there are safety and economical challenges that are commonly associated with nuclear energy and nuclear power plants, but the amount of funding and research going into developing nuclear technologies is quickly solving those issues. The Energy Impact Center launched its OPEN100 project in February 2020 that’s the world’s first open-source blueprint for the design, construction and financing of nuclear power plants and has already received $3 million in funding. ( https://venturebeat.com/2020/02/25/last-energy-raises-3-million-to-fight-climate-change-with-nuclear-energy/ ) OPEN100’s main goal is to collaborate with leaders across industries to develop plans and schematics that require less time and less money to build.

As for additional funding, along with the $160 million awarded to TerraPower and X-energy, mentioned already, in September 2020 the US Department of Energy also awarded $72 million in federal funding to support the development and advancement of carbon capture technologies. $21 million of that went to 18 projects for technologies that remove CO2 from the atmosphere. ( https://www.energy.gov/articles/department-energy-invests-72-million-carbon-capture-technologies )

We can’t wait for new nuclear technologies which won’t be at full maturity best case by 2035. To avoid climate disaster, we must to keep building nuclear technology of the type which has served us so well in the past and whose life we keep extending as you explain in this piece (Gen2 reactors). We are frozen now because we are trying to build new Gen3+ Monsters which are way too expensive and nobody can afford – the North Carolina type. We would have killed civil aviation if we had tried to build the perfect airplane rather than iterating along the way. For 20% cost increase we can produce a Gen2+ addressing immediate concerns and forget the cost prohibitive Gen3+ alternative which has frozen progress. Solar and Wind which are only giving us 9% of our electricity today, and will never give us more than 30% by 2050 because of storage limitations. Restarting proven nuclear providing 20% of our electricity today is the only way to have a 100% decarbonized system by 2050. We may stream in more sophisticated nuclear, of the type you are describing at some point but let’s not wait for that. The urgency is today!!

Your not accounting for freezing or moving rivers this only works for deserts. Nuclear waste must be buried. You not accounting for data thereof.. AT ALL…. if your studying Americas watersheds you would know better.

Gravity energy, solar, water vortex engines, power cells, and shadow generators are the future. Not more toxic waste. Sustainable energy.

Learn, Publish, Educate.*

Working nationally in bioremediation and sustainable buisness I have seen it all.

Nucular waste is riddling our largest water-systems. Forever toxins are found in all of America’s largest watersheds that water decontamination facilities cannot filter out with out Breaking up the water at a molecular level and sponging out toxins from our environment.

Flibe energy is working on a LFTR. The lithium- fluoride rhodium reactor.it will use thorium as a “fertile” fuel.when thethorium is dissolves in molten salt made of lithium fluoride. The thorium as dissolved in a “blanket” of salt surrounded the reactor.when hit with a neutron it absorbs it and transmutates to protactinium233 and then a half-life of 27 days decoys to uranium233(fissile element that powers reactor. Thorium is cheap,it is Abyproduct of processes at rare earth mines. LFTR cannot melt down( three mile island,fukushima)or produce a steam pressure explosion(Chernobyl) because the fuel is already melted in the salt that has liquid range of 400C to1400C at normal atmosphere(no pressurization) . the salt cannot come close to the 1400C point where the liquid salt will turn to a gas because the reactor is dynamically responsive to load amd heat. As the salt becomes hotter the U233 is farther apart,less reactions occur amd the salt will cool down, shoud there be a plant blackout( no power available from reactor,grid,or backup generators,like fukushima)a pipe on the bottom of the reactor is plugged with Flibe salt coiled by refrigerated blower on pipe,with no power to the blower the plug melts and the Flibe will drain into a safety tank that has no grafite moderators and quickly passively cools the salt into a solid safely contained in the tank.even if they reactor were to burst open there is a catch pan that drains to the safety tank.if that fails the worst scenario would be solid salt on the floors that can ne cleaned up .the reactor burns up 99% of the uranics AMD trans_uranics.the 1%left is an isotope of plutonium that NASA would love to have,it has powdered all space probes past the asteroid belt ans it is rare.Gases in the salt,like xenon135( usually a challenge for reactor operators and a contributing factor in the Chernobyl accident) bubble out of the salt like bubbles come out of soda pop amd can be collected.other elements can be removed chemecaly from the salt . the daughter products that have no use are then “waste” and are dangerous for only 300 years vs 10000 + years for solid fuel waste and will fit in a coffee can vs 2 million of those uranium oxide pellets for the same amount of electricity. Two isotopes that can be produced by this machine are medically valuable. Melebnium99 is uses to perform a list of diagnostics tests by doctors and its is getting rare as reactors that make it are getting old and being shut down. Another isotope is bismith213,produces exclusively by the decoy of thorium.Bismuth 213 has just the right amount of radioactivity and half life that doctors want to attached it to antibodies that could attack and kill luekemia and tough cancer’s(like pancreatic cancer which is usually a death sentence). Anothe advantage is the reactor does not require a river or lake for water and am ultimate heat sink. Generators could be run with heated gases like helium. Also the “waste” heat could ne used to desalinate sea water or other industrial processes. Lasty, there is enough thorium on the planet to provide power for centuries to come!

Why don’t we stop using nuclear plants and fossil fuel and just use solar panels yea you may have limited electricity but it’s better then contaminating the air we breath everyday people are dieing way younger then normal and having many different health problems at a young age stuff people go thur in their 50’s or 60’s people 25 to 40 are going thur

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Nuclear Energy

Explore global data on nuclear energy production, and the safety of nuclear technologies..

As the world attempts to transition its energy systems away from fossil fuels towards low-carbon sources of energy, we have a range of energy options: renewable energy technologies such as hydropower, wind, and solar, but also nuclear power. Nuclear energy and renewable technologies typically emit very little CO 2 per unit of energy production, and are also much better than fossil fuels at limiting levels of local air pollution.

But whilst some countries are investing heavily in increasing their nuclear energy supply, others are taking their plants offline. The role that nuclear energy plays in the energy system is therefore very specific to the given country.

How much of our energy comes from nuclear power? How is its role changing over time? In this article we look at levels and changes in nuclear energy generation across the world, and its safety record in comparison to other sources of energy.

Nuclear energy generation

Global generation of nuclear energy.

Nuclear energy – alongside hydropower – is one of our oldest low-carbon energy technologies.

Nuclear power generation has been around since the 1960s, but saw massive growth globally in the 1970s, 80s, and 90s. In the interactive chart shown, we see how global nuclear generation has changed over the past half-century.

Following fast growth during the 1970s to 1990s, global generation has slowed significantly. In fact, we see a sharp dip in nuclear output following the Fukushima tsunami in Japan in 2011 [we look at the impacts of this disaster later in this article] , as countries took plants offline due to safety concerns.

But we also see that in recent years, production has once again increased.

Nuclear energy generation by country

The global trend in nuclear energy generation masks the large differences in what role it plays at the country level.

Some countries get no energy at all from nuclear – or are aiming to eliminate it completely – whilst others get the majority of their power from it.

This interactive chart shows the amount of nuclear energy generated, by country. We see that France, the USA, China, Russia, and South Korea all produce relatively large amounts of nuclear power.

Nuclear in the energy and electricity mix

What share of primary energy comes from nuclear.

We previously looked nuclear output in terms of energy units – how much each country produces in terawatt-hours. But to understand how large of a role nuclear plays in the energy system we need to put this in perspective of total energy consumption.

This interactive chart shows the share of primary energy that comes from nuclear sources.

Note that this data is based on primary energy calculated by the 'substitution method' which attempts to correct for the inefficiencies in fossil fuel production. It does this by converting non-fossil fuel sources to their 'input equivalents': the amount of primary energy that would be required to produce the same amount of energy if it came from fossil fuels. Here we describe this adjustment in more detail.

In 2019, just over 4% of global primary energy came from nuclear power.

Note that this is based on nuclear energy's share in the energy mix. Energy consumption represents the sum of electricity, transport, and heating. We look at the electricity mix below.

What share of electricity comes from nuclear?

In the section above we looked at the role of nuclear in the total energy mix . This includes not only electricity but also transport and heating. Electricity forms only one component of energy consumption.

Since transport and heating tend to be harder to decarbonize – they are more reliant on oil and gas – nuclear and renewables tend to have a higher share in the electricity mix versus the total energy mix.

This interactive chart shows the share of electricity that comes from nuclear sources.

Globally, around 10% of our electricity comes from nuclear. But some countries rely on it heavily, such as Belgium, France, and Ukraine.

Safety of nuclear energy

Energy has been critical to the human progress we’ve seen over the last few centuries. As the United Nations rightly says : “energy is central to nearly every major challenge and opportunity the world faces today.”

But while energy brings us massive benefits, it’s not without its downsides. Energy production can have negative impacts on human health and the environment in three ways.

The first is air pollution : millions of people die prematurely every year as a result of air pollution . Fossil fuels and the burning of biomass – wood, dung, and charcoal – are responsible for most of those deaths.

The second is accidents . This includes accidents that happen in the mining and extraction of the fuels – coal, uranium, rare metals, oil, and gas. It also includes accidents that occur in the transport of raw materials and infrastructure, the construction of the power plant, or their maintenance.

The third is greenhouse gas emissions : fossil fuels are the main source of greenhouse gases, the primary driver of climate change. In 2020, 91% of global CO 2 emissions came from fossil fuels and industry. 1

No energy source is completely safe. They all have short-term impacts on human health, either through air pollution or accidents. And they all have long-term impacts by contributing to climate change.

But, their contribution to each differs enormously. Fossil fuels are both the dirtiest and most dangerous in the short term, and emit the most greenhouse gases per unit of energy. This means that there are thankfully no trade-offs here: low-carbon energy sources are also the safest. From the perspective of both human health and climate change, it matters less whether we transition to nuclear power or renewable energy, and more that we stop relying on fossil fuels.

Nuclear and renewables are far, far safer than fossil fuels

Before we consider the long-term impacts of climate change, let’s look at how each source stacks up in terms of short-term health risks.

To make these comparisons fair we can’t just look at the total deaths from each source: fossil fuels still dominate our global electricity mix, so we would expect that they would kill more people.

Instead, we compare them based on the estimated number of deaths they cause per unit of electricity . This is measured in terawatt-hours. One terawatt-hour is about the same as the annual electricity consumption of 150,000 citizens in the European Union. 2

This includes deaths from air pollution and accidents in the supply chain. 3

Let’s look at this comparison in the chart. Fossil fuels and biomass kill many more people than nuclear and modern renewables per unit of electricity. Coal is, by far, the dirtiest.

Even then, these estimates for fossil fuels are likely to be very conservative. They are based on power plants in Europe, which have good pollution controls, and are based on older models of the health impacts of air pollution. As I discuss in more detail at the end of this article, global death rates from fossil fuels based on the most recent research on air pollution are likely to be even higher.

Our perceptions of the safety of nuclear energy are strongly influenced by two accidents: Chernobyl in Ukraine in 1986, and Fukushima in Japan in 2011. These were tragic events. However, compared to the millions that die from fossil fuels every year the final death tolls were very low. To calculate the death rates used here I assume a death toll of 433 from Chernobyl, and 2,314 from Fukushima. 4 If you are interested in this, I look at how many died in each accident in detail in a related article .

The other source which is heavily influenced by a few large-scale accidents is hydropower. Its death rate since 1965 is 1.3 deaths per TWh. This rate is almost completely dominated by one event: the Banqiao Dam Failure in China in 1975. It killed approximately 171,000 people. Otherwise, hydropower was very safe, with a death rate of just 0.04 deaths per TWh – comparable to nuclear, solar, and wind.

Finally, we have solar and wind. The death rates from both of these sources are low, but not zero. A small number of people die in accidents in supply chains – ranging from helicopter collisions with turbines; fires during the installation of turbines or panels; and drownings on offshore wind sites.

People often focus on the marginal differences at the bottom of the chart – between nuclear, solar, and wind. This comparison is misguided: the uncertainties around these values mean they are likely to overlap.

The key insight is that they are all much, much safer than fossil fuels.

Nuclear energy, for example, results in 99.9% fewer deaths than brown coal; 99.8% fewer than coal; 99.7% fewer than oil; and 97.6% fewer than gas. Wind and solar are just as safe.

Putting death rates from energy in perspective

Looking at deaths per terawatt-hour can seem abstract. Let’s try to put it in perspective.

Let’s consider how many deaths each source would cause for an average town of 150,000 people in the European Union, which – as I’ve said before – consumes one terawatt-hour of electricity per year. Let’s call this town ‘Euroville’.

If Euroville were completely powered by coal we’d expect at least 25 people to die prematurely every year from it.  Most of these people would die from air pollution.

This is how a coal-powered Euroville would compare with towns powered entirely by each energy source:

• Coal: 25 people would die prematurely every year;
• Oil: 18 people would die prematurely every year;
• Gas: 3 people would die prematurely every year;
• Hydropower: In an average year 1 person would die;
• Wind: In an average year nobody would die. A death rate of 0.04 deaths per terawatt-hour means every 25 years a single person would die;
• Nuclear: In an average year nobody would die – only every 33 years would someone die.
• Solar: In an average year nobody would die – only every 50 years would someone die.

The safest energy sources are also the cleanest

The good news is that there is no trade-off between the safest sources of energy in the short term and the least damaging for the climate in the long term. They are one and the same, as the chart below shows.

In the chart on the left-hand side, we have the same comparison of death rates from accidents and air pollution that we just looked at. On the right, we have the amount of greenhouse gases emitted per unit of electricity production.

These are not just the emissions from the burning of fuels but also the mining, transportation, and maintenance over a power plant’s lifetime. 5

Coal, again, is the dirtiest fuel. It emits much more greenhouse gases than other sources – more than a hundred times more than nuclear.

Oil and gas are also much worse than nuclear and renewables but to a lesser extent than coal.

Unfortunately, the global electricity mix is still dominated by fossil fuels: coal, oil, and gas account for around 60% . If we want to stop climate change, we have a great opportunity in front of us: we can transition away from them to nuclear and renewables and also reduce deaths from accidents and air pollution as a side effect. 6

This transition will not only protect future generations, but it will also come with huge health benefits for the current one.

Methodology and notes

Global average death rates from fossil fuels are likely to be even higher than reported in the chart above.

The death rates from coal, oil, and gas that we use in these comparisons are sourced from the paper of Anil Markandya and Paul Wilkinson (2007) in the medical journal, The Lancet . To date, these are the best, peer-reviewed references I could find on the death rates from these sources. These rates are based on electricity production in Europe.

However, there are three key reasons why I think that these death rates are likely to be very conservative, and the global average death rates could be substantially higher.

• European fossil fuel plants have strict pollution controls . Power plants in Europe tend to produce less pollution than the global average, and much less than plants in many low-to-middle-income countries. This means that the pollution generated per unit of electricity is likely to be higher in other parts of the world.
• In other countries, more people will live closer to power plants and therefore be exposed to more pollution . If two countries produce the same amount of coal power, and both have the same pollution controls, the country where power plants are closer to urban centers and cities will have a higher death toll per TWh. This is because more people will be exposed to higher levels of pollution. Power plants in countries such as China, tend to be located closer to cities in many countries than they are in Europe, so we would expect the death rate to be higher than the European figures found by Markandya and Wilkinson (2007). 7
• More recent research on air pollution suggests the health impacts are more severe than earlier research suggested . The analysis by Markandya and Wilkinson was published in 2007. Since then, our understanding of the health impacts of air pollution has increased significantly. More recent research suggests the health impacts are more severe. My colleague, Max Roser, shows this evolution of the research on air pollution deaths in his review of the literature here . Another reason to suspect that the global average rates are much higher is the following: if we take the death rates from Markandya and Wilkinson (2007) and multiply them by global electricity production, the resulting estimates of total global deaths from fossil fuel electricity are much lower than the most recent research. If I multiply the Markandya and Wilkinson (2007) death rates for coal, oil, and gas by their respective global electricity outputs in 2021, I get a total death toll of 280,000 people . 8 This is much lower than the estimates from more recent research. For example, Leliveld et al. (2018) estimate that 3.6 million die from fossil fuels every year. 9 Vohra et al. (2021) even estimate more than double this figure: 8.7 million. 10 Not all of these deaths from fossil fuel air pollution are due to electricity production. But we can estimate how many deaths do. In a recent paper, Leliveld and his colleagues estimated the breakdown of air pollution deaths by sector. They estimate that 12% of all (fossil fuel and pollution from other sources) air pollution deaths come from electricity production. 11

By my calculations, we would expect that 1.1 million to 2.55 million people die from fossil fuels used for electricity production each year. 12 The estimates we get from Markandya and Wilkinson (2007) death rates undercount by a factor of 4 to 9. This would suggest that actual death rates from fossil fuels could be 4 to 9 times higher. That would give a global average death rate from coal of 93 to 224 deaths per TWh . Unfortunately, we do not have more up-to-date death rates for coal, oil, and gas to reference here but improved estimates are sorely needed. The current death rates shown are likely to be underestimated.

We need a timely global database on accidents in energy supply chains

The figures we reference on accidents from nuclear, solar, and wind are based on the most comprehensive figures we have to date. However, they are not perfect, and no timely dataset tracking these accidents exists. This is a key gap in our understanding of the safety of energy sources – and how their safety is changing over time.

To estimate death rates from renewable energy technologies, Sovacool et al. (2016) compiled a database of energy-related accidents across academic databases and news reports. They define an accident as “an unintentional incident or event at an energy facility that led to either one death (or more) or at least $50,000 in property damage,” which is consistent with definitions in the research literature.

This raises several questions as to which incidents should and shouldn’t be attributed to a given energy technology. For example, included in this database were deaths related to an incident where water from a water tank ruptured during a construction test at a solar factory. It’s not clear whether these supply chain deaths should or shouldn’t be attributed to solar technologies.

The comparability of these incidents across the different energy technologies is therefore difficult to assess with high certainty. One additional issue with this analysis by Sovacool et al. (2016) is that its database search was limited to English reports or non-English reports that had been translated. Some of these comparisons could therefore be a slight over- or underestimate. It is, however, unlikely that the position of these technologies would change significantly – renewable and nuclear technologies would consistently come out with a much lower death rate than fossil fuels. Consistent data collection and tracking of incidents across all energy technologies would greatly improve these comparisons.

We need improved estimates of the health impacts of the mining of minerals and materials for all energy sources

The figures presented in this research that I rely on do not include any health impacts from radiation exposure from the mining of metals and minerals used in supply chains.

While we might think that this would only have an impact on nuclear energy, analyses suggest that the carcinogenic toxicity of other sources – including solar, wind, hydropower, coal and gas are all significantly higher across their supply chains. 13

These figures only measure potential exposure to toxic elements for workers. They do not give us estimates of potential death rates, which is why we do not include them in our referenced figures above.

However, the inclusion of these figures would not change the relative results, overall. Fossil fuels – coal, in particular – have a higher carcinogenic toxicity than both nuclear and renewables. Hence the relative difference between them would actually increase, rather than decrease. The key insight would still be the same: fossil fuels are much worse for human health, and both nuclear and modern renewables are similarly safe alternatives.

However, estimates of the health burden of rare minerals in energy supply chains is still an important gap to fill, so that we can learn about their impact and ultimately reduce these risks moving forward.

What was the death toll from Chernobyl and Fukushima?

Nuclear energy is an important source of low-carbon energy. But, there is strong public opposition to it, often because of concerns around safety.

These concerns are often sparked by memories of two nuclear accidents: the Chernobyl disaster in Ukraine in 1986, and Fukushima in Japan in 2011. 14

These two events were by far the largest nuclear accidents in history; the only disasters to receive a level 7 (the maximum classification) on the International Nuclear Event Scale.

How many people died in these nuclear disasters, and what can we learn from them?

How many died from the nuclear accident in Chernobyl?

In April 1986, the core of one of the four reactors at Chernobyl nuclear plant, in Ukraine, melted down and exploded. It was the worst nuclear disaster in human history.

There are several categories of deaths linked to the disaster – for some, we have a good idea of how many died, for others we have a range of plausible deaths.

Direct deaths from the accident

30 people died during or very soon after the incident.

Two plant workers died almost immediately in the explosion from the reactor. Overall, 134 emergency workers, plant operators, and firemen were exposed to levels of radiation high enough to suffer from acute radiation syndrome (ARS). 28 of these 134 workers died in the weeks that followed, which takes the total to 30. 15

Later deaths of workers and firemen

A point of dispute is whether any more of the 134 workers with ARS died as a result of radiation exposure. In 2008, several decades after the incident, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) published a large synthesis of the latest scientific evidence. 15 It reported that a further 19 ARS survivors had died by 2006 . But many of these deaths were not related to any condition caused by radiation exposure. Seven were related to diseases not related to cancers including tuberculosis, liver disease, and stroke; six were from heart attacks; one from a trauma incident; and five died from cancers. 16 It’s difficult to say how many of these deaths could be attributed to the Chernobyl accident – it’s not implausible it played a role in at least some of them, especially the five cancer deaths.

Thyroid cancer deaths in children through contaminated milk

Most of the population was not exposed to levels of radiation that would put them at risk of negative health impacts. However, the slow response to the disaster meant that some individuals were exposed to the short-lived radionuclide Iodine-131 ( 131 I) through the contamination of milk. Radioactive fallout settled on pasture grass across the region; this contaminated milk supplies and leafy vegetables that were consumed in the days immediately after the incident.

This exposure to 131 I has not been linked to increased cancer risk in the adult population, but several studies have shown an increased incidence of thyroid cancer in those who were children and adolescents around this time. Figuring out how many cases of thyroid cancer in this young population were caused by the accident is not straightforward. This is because there was a large increase in screening efforts in the aftermath of the disaster. It’s not uncommon for thyroid cancer cases to go undetected – and have no negative impact on an individual’s life. Increased screening, particularly in child populations, would result in finding many cases of cancer that would normally go undetected.

In 2018, UNSCEAR published its latest findings on thyroid cancers attributed to the Chernobyl disaster. Over the period from 1991 to 2015, there were 19,233 cases of thyroid cancer in patients who were younger than 18 at the time of the disaster across Ukraine, Belarus, and exposed regions of Russia. UNSCEAR concluded that around one-quarter of these cases could be linked to radiation exposure. That would mean 4,808 thyroid cancer cases. 17

By 2005, it was reported that 15 of these thyroid cancer cases had been fatal . 18 However, it was likely that this figure would increase: at least some of those still living with thyroid cancer will eventually die from it.

It’s therefore not possible to give a definitive number, but we can look at survival rates and outcomes to get an estimate. Thankfully the prognosis for thyroid cancer in children is very good. Many patients that have undergone treatment have seen either partial or complete remission. 19 Large-scale studies report a 20-year survival rate of 92% for thyroid cancer. 20 Others show an even better prognosis, with a survival rate of 98% after 40 years. 21

If we combine standard survival rates with our number of radiation-induced cancer cases – 4,808 cases – we might estimate that the number of deaths could be in the range of 96 to 385 . This comes from the assumption of a survival rate of 92% to 98% (or, to flip it, a mortality rate of 2% to 8%). 22 This figure comes with significant uncertainty.

Deaths in the general population

Finally, there has been significant concern about cancer risks to the wider population across Ukraine, Belarus, Russia, and other parts of Europe. This topic remains controversial. Some reports in the early 2000s estimated much higher death tolls ranging from 16,000 to 60,000. 23 In its 2005 report, the WHO estimated a potential death toll of 4,000. 24 These estimates were based on the assumption that a large number of people were exposed to elevated levels of radioactivity, and that radioactivity increases cancer risk, even at very low levels of exposure (the so-called ‘ linear no-threshold model ’ of radiation exposure).

More recent studies suggest that these estimates were too high. In 2008, the UNSCEAR concluded that radioactive exposure to the general public was very low, and that it does not expect adverse health impacts in the countries affected by Chernobyl, or the rest of Europe. 25 In 2018 it published a follow-up report, which came to the same conclusion.

If the health impacts of radiation were directly and linearly related to the level of exposure, we would expect to find that cancer rates were highest in regions closest to the Chernobyl site, and would decline with distance from the plant. But studies do not find this. Cancer rates in Ukraine, for example, were not higher in locations closer to the site 26 This suggests that there is a lower limit to the level at which radiation exposure has negative health impacts. And that most people were not exposed to doses higher than this.

Combined death toll from Chernobyl

To summarize the previous paragraphs:

• 2 workers died in the blast.
• 28 workers and firemen died in the weeks that followed from acute radiation syndrome (ARS).
• 19 ARS survivors had died later, by 2006 ; most were from causes not related to radiation, but it’s not possible to rule all of them out (especially five that were cancer-related).
• 15 people died from thyroid cancer due to milk contamination . These deaths were among children who were exposed to 131 I from milk and food in the days after the disaster. This could increase to between 96 and 384 deaths, however, this figure is highly uncertain.
• There is currently no evidence of adverse health impacts in the general population across affected countries, or wider Europe .

Combined, the confirmed death toll from Chernobyl is less than 100. We still do not know the true death toll of the disaster. My best approximation is that the true death toll is in the range of 300 to 500 based on the available evidence. 27

How many died from the nuclear accident in Fukushima?

In March 2011, there was an accident at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan. This accident was caused by the 2011 Tōhoku earthquake and tsunami – the most powerful earthquake recorded in Japan’s history.

Despite it being such a large event, so far, only one death has been attributed to the disaster. This includes both the direct impact of the accident itself and the radiation exposure that followed. However, it’s estimated that several thousand died indirectly from the stress and disruption of evacuation.

Direct and cancer deaths from the accident

No one died directly from the disaster. However, 40 to 50 people were injured as a result of physical injury from the blast, or radiation burns.

In 2018, the Japanese government reported that one worker has since died from lung cancer as a result of radiation exposure from the event.

Over the last decade, many studies have assessed whether there has been any increased cancer risk for local populations. There appears to be no increased risk of cancer or other radiation-related health impacts .

In 2016, the World Health Organization noted that there was a very low risk of increased cancer deaths in Japan. 28 Several reports from the UN Scientific Committee on the Effects of Atomic Radiation came to the same conclusion: they report that any increase in radiation exposure for local populations was very low and they do not expect any increase in radiation-related health impacts. 29

Deaths from evacuation

A more difficult question is how many people died indirectly through the response and evacuation of locals from the area around Fukushima. Within a few weeks of the accident, more than 160,000 people had moved away, either from official evacuation efforts or voluntarily from fear of further radioactive releases. Many were forced to stay in overcrowded gyms, schools, and public facilities for several months until more permanent emergency housing became available.

The year after the 2011 disaster, the Japanese government estimated that 573 people had died indirectly as a result of the physical and mental stress of evacuation. 30 Since then, more rigorous assessments of increased mortality have been done, and this figure was revised to 2,313 deaths in September 2020.

These indirect deaths were attributed to the overall physical and mental stress of evacuation; being moved out of care settings; and disruption to healthcare facilities.

It’s important to bear in mind that the region was also trying to deal with the aftermath of an earthquake and tsunami: this makes it difficult to completely separate the indirect deaths related to the nuclear disaster disruptions, and those of the tsunami itself.

Combined, the confirmed death toll from Fukushima is therefore 2,314.

What can we learn from these nuclear disasters?

The context and response to these disasters were very different, and this is reflected in what people died from in the aftermath.

Many more people directly died from Chernobyl than from Fukushima. There are several reasons for this.

The first was reactor design . The nuclear reactors at Chernobyl were poorly designed to deal with this meltdown scenario. Its fatal RBMK reactor had no containment structure, allowing radioactive material to spill into the atmosphere. Fukushima’s reactors did have steel-and-concrete containment structures, although it’s likely that at least one of these was also breached.

Crucially, the cooling systems of both plants worked very differently; at Chernobyl, the loss of cooling water as steam actually served to accelerate reactivity levels in the reactor core, creating a positive feedback loop toward the fatal explosion. The opposite is true of Fukushima, where the reactivity reduced as temperatures rose, effectively operating as a self-shutdown measure.

The second factor was government response . In the case of Fukushima, the Japanese government responded quickly to the crisis with evacuation efforts extending rapidly from a 3-kilometer (km), to a 10-km, to a 20-km radius whilst the incident at the site continued to unfold. In contrast, the response in the former Soviet Union was one of denial and secrecy.

It’s reported that in the days that followed the Chernobyl disaster, residents in surrounding areas were uninformed of the radioactive material in the air around them. In fact, it took at least three days for the Soviet Union to admit an accident had taken place, and did so after radioactive sensors at a Swedish plant were triggered by dispersing radionuclides. As we saw above, it’s estimated that approximately 4,808 thyroid cancer cases in children and adolescents could be linked to radiation exposure from contaminated milk and foods. This could have been prevented by an earlier response.

Finally, while an early response from the Japanese government may have prevented a significant number of deaths, many have questioned whether the scale of the evacuation effort – where more than 160,000 people were displaced – was necessary. 31 As we see from the figures above, evacuation stress and disruption are estimated to have contributed to several thousand early deaths. Only one death has been linked to the impact of radiation. We don’t know what the possible death toll would have been without any evacuation. That’s why a no-evacuation strategy, if a future accident was to occur, seems unlikely. However, many have called for governments to develop early assessments and protocols of radiation risks, the scale of evacuation needed, and infrastructure to make sure that the disruption to those who are displaced is kept to a minimum. 32

Nuclear is one of the safest energy sources

No energy source comes with zero negative impact. We often think of nuclear energy as being more dangerous than other sources because these low-frequency but highly visible events come to mind.

However, when we compare the death rates from nuclear energy to other sources, we see that it’s one of the safest. The numbers that have died from nuclear accidents are very small in comparison to the millions that die from air pollution from fossil fuels every year . As the linked post shows, the death rate from nuclear is roughly comparable with most renewable energy technologies.

Since nuclear is also a key source of low-carbon energy, it can play a key role in a sustainable energy mix alongside renewables.

​​Pierre Friedlingstein, Matthew W. Jones, Michael O'Sullivan, Robbie M. Andrew, Dorothee, C. E. Bakker, Judith Hauck, Corinne Le Quéré, Glen P. Peters, Wouter Peters, Julia Pongratz, Stephen Sitch, Josep G. Canadell, Philippe Ciais, Rob B. Jackson, Simone R. Alin, Peter Anthoni, Nicholas R. Bates, Meike Becker, Nicolas Bellouin, Laurent Bopp, Thi Tuyet Trang Chau, Frédéric Chevallier, Louise P. Chini, Margot Cronin, Kim I. Currie, Bertrand Decharme, Laique M. Djeutchouang, Xinyu Dou, Wiley Evans, Richard A. Feely, Liang Feng, Thomas Gasser, Dennis Gilfillan, Thanos Gkritzalis, Giacomo Grassi, Luke Gregor, Nicolas Gruber, Özgür Gürses, Ian Harris, Richard A. Houghton, George C. Hurtt, Yosuke Iida, Tatiana Ilyina, Ingrid T. Luijkx, Atul Jain, Steve D. Jones, Etsushi Kato, Daniel Kennedy, Kees Klein Goldewijk, Jürgen Knauer, Jan Ivar Korsbakken, Arne Körtzinger, Peter Landschützer, Siv K. Lauvset, Nathalie Lefèvre, Sebastian Lienert, Junjie Liu, Gregg Marland, Patrick C. McGuire, Joe R. Melton, David R. Munro, Julia E.M.S Nabel Shin-Ichiro Nakaoka, Yosuke Niwa, Tsuneo Ono, Denis Pierrot, Benjamin Poulter, Gregor Rehder, Laure Resplandy, Eddy Robertson, Christian Rödenbeck, Thais M Rosan, Jörg Schwinger, Clemens Schwingshackl, Roland Séférian, Adrienne J. Sutton, Colm Sweeney, Toste Tanhua, Pieter P Tans, Hanqin Tian, Bronte Tilbrook, Francesco Tubiello, Guido van der Werf, Nicolas Vuichard, Chisato Wada Rik Wanninkhof, Andrew J. Watson, David Willis, Andrew J. Wiltshire, Wenping Yuan, Chao Yue, Xu Yue, Sönke Zaehle, Jiye Zeng. Global Carbon Budget 2021, Earth Syst. Sci. Data, 2021.

Per capita electricity consumption in the EU-27 in 2021 was around 6,400 kWh.

1 terawatt-hour is equal to 1,000,000,000 kilowatt-hours. So, we get this figure by dividing 1,000,000,000 by 6,400 ≈ 150,000 people.

The following sources were used to calculate these death rates.

Fossil fuels and biomass = these figures are taken directly from Markandya, A., & Wilkinson, P. (2007). Electricity generation and health . The Lancet , 370(9591), 979-990.

Nuclear = I have calculated these figures based on the assumption of 433 deaths from Chernobyl and 2314 from Fukushima. These figures are based on the most recent estimates from UNSCEAR and the Government of Japan. In a related article , I detail where these figures come from.

I have calculated death rates by dividing this figure by cumulative global electricity production from nuclear from 1965 to 2021, which is 96,876 TWh.

Hydropower = The paper by Sovacool et al. (2016) provides a death rate for hydropower from 1990 to 2013. However, this period excludes some very large hydropower accidents which occurred prior to 1990. I have therefore calculated a death rate for hydropower from 1965 to 2021 based on the list of hydropower accidents provided in Sovacool et al. (2016), which extends back to the 1950s. Since this database ends in 2013, I have also included the Saddle Dam accident in Laos in 2018, which killed 71 people.

The total number of deaths from hydropower accidents from 1965 to 2021 was approximately 176,000. 171,000 of these deaths were from the Banqian Dam Failure in China in 1975.

I have calculated death rates by dividing this figure by cumulative global electricity production from hydropower from 1965 to 2021, which is 138,175 TWh.

Solar and wind = these figures are taken directly from: Sovacool, B. K., Andersen, R., Sorensen, S., Sorensen, K., Tienda, V., Vainorius, A., … & Bjørn-Thygesen, F. (2016). Balancing safety with sustainability: assessing the risk of accidents for modern low-carbon energy systems . Journal of Cleaner Production , 112, 3952-3965. In this analysis, the authors compiled a database of as many energy-related accidents as possible based on an extensive search of academic databases and news reports, and derived death rates for each source over the period from 1990 to 2013. Since this database has not been extended since then, it’s not possible to provide post-2013 death rates.

UNSCEAR (2008). Sources and effects of Ionizing Radiation. UNSCEAR 2008 Report to the General Assembly with Scientific Annexes. Available online .

Report of the United Nations Scientific Committee on the Effects of Atomic Radiation. General Assembly Official Records, Sixty-eighth session, Supplement No. 46. New York: United Nations, Sixtieth session, May 27–31, 2013.

The main figures used in this analysis come from the United Nations Economic Commission for Europe (UNECE) Lifecycle Assessment of Electricity Generation Options , published in 2022.

These figures are similar to those published by the IPCC, and other energy organizations.

Schlömer S., T. Bruckner, L. Fulton, E. Hertwich, A. McKinnon, D. Perczyk, J. Roy, R. Schaeffer, R. Sims, P. Smith, and R. Wiser, 2014: Annex III: Technology-specific cost and performance parameters. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

The figures for some technologies – such as solar – vary significantly depending on where they’re manufactured (and the electricity mix of that country). Estimates range from around 23 grams CO 2 per kWh to 82 grams.

The carbon intensity of the production of these technologies is likely to improve over time. The Carbon Brief provides a clear discussion of the significance of more recent lifecycle analyses in detail here .

Since oil is conventionally not used for electricity production, it is not included in the IPCC’s reported figures per kilowatt-hour. Figures for oil have therefore been taken from Turconi et al. (2013). It reports emissions in kilograms of CO2eq per megawatt-hour. Emissions factors for all other technologies are consistent with results from the IPCC. The range it gives for oil is 530–900: I have taken the midpoint estimate (715 kgCO2eq/MWh, or 715 gCO2eq/kWh).

Turconi, R., Boldrin, A., & Astrup, T. (2013). Life cycle assessment (LCA) of electricity generation technologies: Overview, comparability and limitations . Renewable and Sustainable Energy Reviews , 28, 555-565.

Burgherr, P., & Hirschberg, S. (2014). Comparative risk assessment of severe accidents in the energy sector . Energy Policy, 74, S45-S56.

McCombie, C., & Jefferson, M. (2016). Renewable and nuclear electricity: Comparison of environmental impacts. Energy Policy, 96, 758-769.

Hirschberg, S., Bauer, C., Burgherr, P., Cazzoli, E., Heck, T., Spada, M., & Treyer, K. (2016). Health effects of technologies for power generation: Contributions from normal operation, severe accidents and terrorist threat . Reliability Engineering & System Safety, 145, 373-387.

Luderer, G., Pehl, M., Arvesen, A., Gibon, T., Bodirsky, B. L., de Boer, H. S., … & Mima, S. (2019). Environmental co-benefits and adverse side-effects of alternative power sector decarbonization strategies . Nature Communications, 10(1), 1-13.

Hertwich, E. G., Gibon, T., Bouman, E. A., Arvesen, A., Suh, S., Heath, G. A., … & Shi, L. (2015). Integrated life-cycle assessment of electricity-supply scenarios confirms global environmental benefit of low-carbon technologies . Proceedings of the National Academy of Sciences, 112(20), 6277-6282.

Xie, L., Huang, Y., & Qin, P. (2018). Spatial distribution of coal-fired power plants in China. Environment and Development Economics, 23(4), 495-515.

Coal: 24.62 deaths per TWh * 10,042 TWh = 247,000 deaths; Oil: 18.43 deaths per TWh * 852 TWh = 16,000 deaths; Gas: 2.82 deaths per TWh * 6,098 TWh = 17,000 deaths. This sums to a total of 280,000 people.

Lelieveld, J., Klingmüller, K., Pozzer, A., Burnett, R. T., Haines, A., & Ramanathan, V. (2019). Effects of fossil fuel and total anthropogenic emission removal on public health and climate . Proceedings of the National Academy of Sciences, 116(15), 7192-7197.

Vohra, K., Vodonos, A., Schwartz, J., Marais, E. A., Sulprizio, M. P., & Mickley, L. J. (2021). Global mortality from outdoor fine particle pollution generated by fossil fuel combustion: Results from GEOS-Chem . Environmental Research, 195, 110754.

Chowdhury, S., Pozzer, A., Haines, A., Klingmueller, K., Münzel, T., Paasonen, P., ... & Lelieveld, J. (2022). Global health burden of ambient PM2.5 and the contribution of anthropogenic black carbon and organic aerosols . Environment International, 159, 107020.

Leliveld et al. (2019) estimate that 8.8 million people die from all sources of air pollution each year. If we multiply this figure by 12%, we get 1.1 million people. Vohra et al. (2021) estimate that the death toll is 2.4 times higher than Leliveld et al. (2019). This would give a figure of 2.55 million deaths [1.1 million * 2.4]

UNECE (2021). Lifecycle Assessment of Electricity Generation Options . United Nations Economic Commission for Europe.

The third incident that often comes to mind was the Three Mile Island accident in the US in 1979. This was rated as a level five event (“Accident with Wider Consequences”) on the seven-point International Nuclear Event Scale .

No one died directly from this incident, and follow-up epidemiological studies have not found a clear link between the incident and long-term health impacts.

Hatch, M. C., Beyea, J., Nieves, J. W., & Susser, M. (1990). Cancer near the Three Mile Island nuclear plant: radiation emissions . American Journal of Epidemiology , 132(3), 397-412.

Hatch, M. C., Wallenstein, S., Beyea, J., Nieves, J. W., & Susser, M. (1991). Cancer rates after the Three Mile Island nuclear accident and proximity of residence to the plant . American Journal of Public Healt h, 81(6), 719-724.

The UNSCEAR (2008) report lists the causes of death in each of these survivors in Table D4 of the appendix.

25% of 19,233 is 4808 cases.

This figure was included in the UNSCEAR’s 2008 report. I found no updated figure for fatalities in its 2018 report.

Reiners, C. (2011). Clinical experiences with radiation induced thyroid cancer after Chernobyl. Genes, 2(2), 374-383.

Hogan, A. R., Zhuge, Y., Perez, E. A., Koniaris, L. G., Lew, J. I., & Sola, J. E. (2009). Pediatric thyroid carcinoma: incidence and outcomes in 1753 patients. Journal of Surgical Research, 156(1), 167-172.

Hay, I. D., Gonzalez-Losada, T., Reinalda, M. S., Honetschlager, J. A., Richards, M. L., & Thompson, G. B. (2010). Long-term outcome in 215 children and adolescents with papillary thyroid cancer treated during 1940 through 2008. World Journal of Surgery , 34(6), 1192-1202.

2% of 4808 is 96, and 8% is 385.

Cardis et al. (2006). Estimates of the cancer burden in Europe from radioactive fallout from the Chernobyl accident. International Journal of Cancer. Available online .

Fairlie and Sumner (2006). An independent scientific evaluation of health and environmental effects 20 years after the nuclear disaster providing critical analysis of a recent report by the International Atomic Energy Agency (IAEA) and the World Health Organisation (WHO). Available online .

IAEA, WHO (2005/06). Chernobyl’s Legacy: Health, Environmental and Socio-Economic Impacts .

As it details in its report:“The vast majority of the population were exposed to low levels of radiation comparable, at most, to a few times the annual natural background radiation levels and need not live in fear of serious health consequences. This is true for the populations of the three countries most affected by the Chernobyl accident, Belarus, the Russian Federation and Ukraine, and even more so for the populations of other European countries.”

“To date, there has been no persuasive evidence of any other health effect in the general population that can be attributed to radiation exposure”

Leung, K. M., Shabat, G., Lu, P., Fields, A. C., Lukashenko, A., Davids, J. S., & Melnitchouk, N. (2019). Trends in solid tumor incidence in Ukraine 30 years after chernobyl . Journal of Global Oncology , 5 , 1-10.

When we report on the safety of energy sources – in this article – I take the upper number of 433 deaths to be conservative.

World Health Organization (2016). FAQs: Fukushima Five Years On. Available online .

To quote UNSCEAR directly: “The doses to the general public, both those incurred during the first year and estimated for their lifetimes, are generally low or very low. No discernible increased incidence of radiation-related health effects are expected among exposed members of the public or their descendants.”

Report of the United Nations Scientific Committee on the Effects of Atomic Radiation. General Assembly Official Records , Sixty-eighth session, Supplement No. 46. New York: United Nations, Sixtieth session, May 27–31, 2013.

The Yomiuri Shimbun, 573 deaths ‘related to nuclear crisis’, The Yomiuri Shimbun, 5 February 2012, https://wayback.archive-it.org/all/20120204190315/http://www.yomiuri.co.jp/dy/national/T120204003191.htm.

Hayakawa, M. (2016). Increase in disaster-related deaths: risks and social impacts of evacuation . Annals of the ICRP, 45(2_suppl), 123-128.

Normile (2021). Nuclear medicine: After 10 years advising survivors of the Fukushima disaster about radiation, Masaharu Tsubokura thinks the evacuations posed a far bigger health risk . Science .

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Nuclear Power in a Clean Energy System

About this report.

With nuclear power facing an uncertain future in many countries, the world risks a steep decline in its use in advanced economies that could result in billions of tonnes of additional carbon emissions. Some countries have opted out of nuclear power in light of concerns about safety and other issues. Many others, however, still see a role for nuclear in their energy transitions but are not doing enough to meet their goals.

The publication of the IEA's first report addressing nuclear power in nearly two decades brings this important topic back into the global energy debate.

Key findings

Nuclear power is the second-largest source of low-carbon electricity today.

Nuclear power is the second-largest source of low-carbon electricity today, with 452 operating reactors providing 2700 TWh of electricity in 2018, or 10% of global electricity supply.

In advanced economies, nuclear has long been the largest source of low-carbon electricity, providing 18% of supply in 2018. Yet nuclear is quickly losing ground. While 11.2 GW of new nuclear capacity was connected to power grids globally in 2018 – the highest total since 1990 – these additions were concentrated in China and Russia.

Global low-carbon power generation by source, 2018

Cumulative co2 emissions avoided by global nuclear power in selected countries, 1971-2018, an aging nuclear fleet.

In the absense of further lifetime extensions and new projects could result in an additional 4 billion tonnes of CO2 emissions, underlining the importance of the nuclear fleet to low-carbon energy transitions around the globe. In emerging and developing economies, particularly China, the nuclear fleet will provide low-carbon electricity for decades to come.

However the nuclear fleet in advanced economies is 35 years old on average and many plants are nearing the end of their designed lifetimes. Given their age, plants are beginning to close, with 25% of existing nuclear capacity in advanced economies expected to be shut down by 2025.

It is considerably cheaper to extend the life of a reactor than build a new plant, and costs of extensions are competitive with other clean energy options, including new solar PV and wind projects. Nevertheless they still represent a substantial capital investment. The estimated cost of extending the operational life of 1 GW of nuclear capacity for at least 10 years ranges from $500 million to just over $1 billion depending on the condition of the site.

However difficult market conditions are a barrier to lifetime extension investments. An extended period of low wholesale electricity prices in most advanced economies has sharply reduced or eliminated margins for many technologies, putting nuclear at risk of shutting down early if additional investments are needed. As such, the feasibility of extensions depends largely on domestic market conditions.

Age profile of nuclear power capacity in selected regions, 2019

United states, levelised cost of electricity in the united states, 2040, european union, levelised cost of electricity in the european union, 2040, levelised cost of electricity in japan, 2040, the nuclear fade case, nuclear capacity operating in selected advanced economies in the nuclear fade case, 2018-2040, wind and solar pv generation by scenario 2019-2040, policy recommendations.

In this context, countries that intend to retain the option of nuclear power should consider the following actions:

• Keep the option open:  Authorise lifetime extensions of existing nuclear plants for as long as safely possible. 
• Value dispatchability:  Design the electricity market in a way that properly values the system services needed to maintain electricity security, including capacity availability and frequency control services. Make sure that the providers of these services, including nuclear power plants, are compensated in a competitive and non-discriminatory manner.
• Value non-market benefits:  Establish a level playing field for nuclear power with other low-carbon energy sources in recognition of its environmental and energy security benefits and remunerate it accordingly.
• Update safety regulations:  Where necessary, update safety regulations in order to ensure the continued safe operation of nuclear plants. Where technically possible, this should include allowing flexible operation of nuclear power plants to supply ancillary services.
• Create a favourable financing framework:  Create risk management and financing frameworks that facilitate the mobilisation of capital for new and existing plants at an acceptable cost taking the risk profile and long time-horizons of nuclear projects into consideration.
• Support new construction:  Ensure that licensing processes do not lead to project delays and cost increases that are not justified by safety requirements.
• Support innovative new reactor designs:  Accelerate innovation in new reactor designs with lower capital costs and shorter lead times and technologies that improve the operating flexibility of nuclear power plants to facilitate the integration of growing wind and solar capacity into the electricity system.
• Maintain human capital:  Protect and develop the human capital and project management capabilities in nuclear engineering.

Executive summary

Nuclear power can play an important role in clean energy transitions.

Nuclear power today makes a significant contribution to electricity generation, providing 10% of global electricity supply in 2018.  In advanced economies 1 , nuclear power accounts for 18% of generation and is the largest low-carbon source of electricity. However, its share of global electricity supply has been declining in recent years. That has been driven by advanced economies, where nuclear fleets are ageing, additions of new capacity have dwindled to a trickle, and some plants built in the 1970s and 1980s have been retired. This has slowed the transition towards a clean electricity system. Despite the impressive growth of solar and wind power, the overall share of clean energy sources in total electricity supply in 2018, at 36%, was the same as it was 20 years earlier because of the decline in nuclear. Halting that slide will be vital to stepping up the pace of the decarbonisation of electricity supply.

A range of technologies, including nuclear power, will be needed for clean energy transitions around the world.  Global energy is increasingly based around electricity. That means the key to making energy systems clean is to turn the electricity sector from the largest producer of CO 2 emissions into a low-carbon source that reduces fossil fuel emissions in areas like transport, heating and industry. While renewables are expected to continue to lead, nuclear power can also play an important part along with fossil fuels using carbon capture, utilisation and storage. Countries envisaging a future role for nuclear account for the bulk of global energy demand and CO 2 emissions. But to achieve a trajectory consistent with sustainability targets – including international climate goals – the expansion of clean electricity would need to be three times faster than at present. It would require 85% of global electricity to come from clean sources by 2040, compared with just 36% today. Along with massive investments in efficiency and renewables, the trajectory would need an 80% increase in global nuclear power production by 2040.

Nuclear power plants contribute to electricity security in multiple ways.  Nuclear plants help to keep power grids stable. To a certain extent, they can adjust their operations to follow demand and supply shifts. As the share of variable renewables like wind and solar photovoltaics (PV) rises, the need for such services will increase. Nuclear plants can help to limit the impacts from seasonal fluctuations in output from renewables and bolster energy security by reducing dependence on imported fuels.

Lifetime extensions of nuclear power plants are crucial to getting the energy transition back on track

Policy and regulatory decisions remain critical to the fate of ageing reactors in advanced economies.  The average age of their nuclear fleets is 35 years. The European Union and the United States have the largest active nuclear fleets (over 100 gigawatts each), and they are also among the oldest: the average reactor is 35 years old in the European Union and 39 years old in the United States. The original design lifetime for operations was 40 years in most cases. Around one quarter of the current nuclear capacity in advanced economies is set to be shut down by 2025 – mainly because of policies to reduce nuclear’s role. The fate of the remaining capacity depends on decisions about lifetime extensions in the coming years. In the United States, for example, some 90 reactors have 60-year operating licenses, yet several have already been retired early and many more are at risk. In Europe, Japan and other advanced economies, extensions of plants’ lifetimes also face uncertain prospects.

Economic factors are also at play.  Lifetime extensions are considerably cheaper than new construction and are generally cost-competitive with other electricity generation technologies, including new wind and solar projects. However, they still need significant investment to replace and refurbish key components that enable plants to continue operating safely. Low wholesale electricity and carbon prices, together with new regulations on the use of water for cooling reactors, are making some plants in the United States financially unviable. In addition, markets and regulatory systems often penalise nuclear power by not pricing in its value as a clean energy source and its contribution to electricity security. As a result, most nuclear power plants in advanced economies are at risk of closing prematurely.

The hurdles to investment in new nuclear projects in advanced economies are daunting

What happens with plans to build new nuclear plants will significantly affect the chances of achieving clean energy transitions.  Preventing premature decommissioning and enabling longer extensions would reduce the need to ramp up renewables. But without new construction, nuclear power can only provide temporary support for the shift to cleaner energy systems. The biggest barrier to new nuclear construction is mobilising investment.  Plans to build new nuclear plants face concerns about competitiveness with other power generation technologies and the very large size of nuclear projects that require billions of dollars in upfront investment. Those doubts are especially strong in countries that have introduced competitive wholesale markets.

A number of challenges specific to the nature of nuclear power technology may prevent investment from going ahead.  The main obstacles relate to the sheer scale of investment and long lead times; the risk of construction problems, delays and cost overruns; and the possibility of future changes in policy or the electricity system itself. There have been long delays in completing advanced reactors that are still being built in Finland, France and the United States. They have turned out to cost far more than originally expected and dampened investor interest in new projects. For example, Korea has a much better record of completing construction of new projects on time and on budget, although the country plans to reduce its reliance on nuclear power.

Without nuclear investment, achieving a sustainable energy system will be much harder

A collapse in investment in existing and new nuclear plants in advanced economies would have implications for emissions, costs and energy security.  In the case where no further investments are made in advanced economies to extend the operating lifetime of existing nuclear power plants or to develop new projects, nuclear power capacity in those countries would decline by around two-thirds by 2040. Under the current policy ambitions of governments, while renewable investment would continue to grow, gas and, to a lesser extent, coal would play significant roles in replacing nuclear. This would further increase the importance of gas for countries’ electricity security. Cumulative CO 2 emissions would rise by 4 billion tonnes by 2040, adding to the already considerable difficulties of reaching emissions targets. Investment needs would increase by almost USD 340 billion as new power generation capacity and supporting grid infrastructure is built to offset retiring nuclear plants.

Achieving the clean energy transition with less nuclear power is possible but would require an extraordinary effort.  Policy makers and regulators would have to find ways to create the conditions to spur the necessary investment in other clean energy technologies. Advanced economies would face a sizeable shortfall of low-carbon electricity. Wind and solar PV would be the main sources called upon to replace nuclear, and their pace of growth would need to accelerate at an unprecedented rate. Over the past 20 years, wind and solar PV capacity has increased by about 580 GW in advanced economies. But in the next 20 years, nearly five times that much would need to be built to offset nuclear’s decline. For wind and solar PV to achieve that growth, various non-market barriers would need to be overcome such as public and social acceptance of the projects themselves and the associated expansion in network infrastructure. Nuclear power, meanwhile, can contribute to easing the technical difficulties of integrating renewables and lowering the cost of transforming the electricity system.

With nuclear power fading away, electricity systems become less flexible.  Options to offset this include new gas-fired power plants, increased storage (such as pumped storage, batteries or chemical technologies like hydrogen) and demand-side actions (in which consumers are encouraged to shift or lower their consumption in real time in response to price signals). Increasing interconnection with neighbouring systems would also provide additional flexibility, but its effectiveness diminishes when all systems in a region have very high shares of wind and solar PV.

Offsetting less nuclear power with more renewables would cost more

Taking nuclear out of the equation results in higher electricity prices for consumers.  A sharp decline in nuclear in advanced economies would mean a substantial increase in investment needs for other forms of power generation and the electricity network. Around USD 1.6 trillion in additional investment would be required in the electricity sector in advanced economies from 2018 to 2040. Despite recent declines in wind and solar costs, adding new renewable capacity requires considerably more capital investment than extending the lifetimes of existing nuclear reactors. The need to extend the transmission grid to connect new plants and upgrade existing lines to handle the extra power output also increases costs. The additional investment required in advanced economies would not be offset by savings in operational costs, as fuel costs for nuclear power are low, and operation and maintenance make up a minor portion of total electricity supply costs. Without widespread lifetime extensions or new projects, electricity supply costs would be close to USD 80 billion higher per year on average for advanced economies as a whole.

Strong policy support is needed to secure investment in existing and new nuclear plants

Countries that have kept the option of using nuclear power need to reform their policies to ensure competition on a level playing field.  They also need to address barriers to investment in lifetime extensions and new capacity. The focus should be on designing electricity markets in a way that values the clean energy and energy security attributes of low-carbon technologies, including nuclear power.

Securing investment in new nuclear plants would require more intrusive policy intervention given the very high cost of projects and unfavourable recent experiences in some countries.  Investment policies need to overcome financing barriers through a combination of long-term contracts, price guarantees and direct state investment.

Interest is rising in advanced nuclear technologies that suit private investment such as small modular reactors (SMRs).  This technology is still at the development stage. There is a case for governments to promote it through funding for research and development, public-private partnerships for venture capital and early deployment grants. Standardisation of reactor designs would be crucial to benefit from economies of scale in the manufacturing of SMRs.

Continued activity in the operation and development of nuclear technology is required to maintain skills and expertise.  The relatively slow pace of nuclear deployment in advanced economies in recent years means there is a risk of losing human capital and technical know-how. Maintaining human skills and industrial expertise should be a priority for countries that aim to continue relying on nuclear power.

The following recommendations are directed at countries that intend to retain the option of nuclear power. The IEA makes no recommendations to countries that have chosen not to use nuclear power in their clean energy transition and respects their choice to do so.

• Keep the option open:  Authorise lifetime extensions of existing nuclear plants for as long as safely possible.
• Value non-market benefits:  Establish a level playing field for nuclear power with other low carbon energy sources in recognition of its environmental and energy security benefits and remunerate it accordingly.
• Create an attractive financing framework:  Set up risk management and financing frameworks that can help mobilise capital for new and existing plants at an acceptable cost, taking the risk profile and long time horizons of nuclear projects into consideration.
• Support new construction:  Ensure that licensing processes do not lead to project delays and cost increases that are not justified by safety requirements. Support standardisation and enable learning-by-doing across the industry.
• Support innovative new reactor designs:  Accelerate innovation in new reactor designs, such as small modular reactors (SMRs), with lower capital costs and shorter lead times and technologies that improve the operating flexibility of nuclear power plants to facilitate the integration of growing wind and solar capacity into the electricity system.

Advanced economies consist of Australia, Canada, Chile, the 28 members of the European Union, Iceland, Israel, Japan, Korea, Mexico, New Zealand, Norway, Switzerland, Turkey and the United States.

Reference 1

Cite report.

IEA (2019), Nuclear Power in a Clean Energy System , IEA, Paris https://www.iea.org/reports/nuclear-power-in-a-clean-energy-system, Licence: CC BY 4.0

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Nuclear Energy

Nuclear energy is the energy in the nucleus, or core, of an atom. Nuclear energy can be used to create electricity, but it must first be released from the atom.

Engineering, Physics

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Nuclear energy is the energy in the nucleus , or core, of an atom . Atoms are tiny units that make up all matter in the universe , and energy is what holds the nucleus together. There is a huge amount of energy in an atom 's dense nucleus . In fact, the power that holds the nucleus together is officially called the " strong force ." Nuclear energy can be used to create electricity , but it must first be released from the atom . In the process of  nuclear fission , atoms are split to release that energy. A nuclear reactor , or power plant , is a series of machines that can control nuclear fission to produce electricity . The fuel that nuclear reactors use to produce nuclear fission is pellets of the element uranium . In a nuclear reactor , atoms of uranium are forced to break apart. As they split, the atoms release tiny particles called fission products. Fission products cause other uranium atoms to split, starting a chain reaction . The energy released from this chain reaction creates heat. The heat created by nuclear fission warms the reactor's cooling agent . A cooling agent is usually water, but some nuclear reactors use liquid metal or molten salt . The cooling agent , heated by nuclear fission , produces steam . The steam turns turbines , or wheels turned by a flowing current . The turbines drive generators , or engines that create electricity . Rods of material called nuclear poison can adjust how much electricity is produced. Nuclear poisons are materials, such as a type of the element xenon , that absorb some of the fission products created by nuclear fission . The more rods of nuclear poison that are present during the chain reaction , the slower and more controlled the reaction will be. Removing the rods will allow a stronger chain reaction and create more electricity . As of 2011, about 15 percent of the world's electricity is generated by nuclear power plants . The United States has more than 100 reactors, although it creates most of its electricity from fossil fuels and hydroelectric energy . Nations such as Lithuania, France, and Slovakia create almost all of their electricity from nuclear power plants . Nuclear Food: Uranium Uranium is the fuel most widely used to produce nuclear energy . That's because uranium atoms split apart relatively easily. Uranium is also a very common element, found in rocks all over the world. However, the specific type of uranium used to produce nuclear energy , called U-235 , is rare. U-235 makes up less than one percent of the uranium in the world.

Although some of the uranium the United States uses is mined in this country, most is imported . The U.S. gets uranium from Australia, Canada, Kazakhstan, Russia, and Uzbekistan. Once uranium is mined, it must be extracted from other minerals . It must also be processed before it can be used. Because nuclear fuel can be used to create nuclear weapons as well as nuclear reactors , only nations that are part of the Nuclear Non-Proliferation Treaty (NPT) are allowed to import uranium or plutonium , another nuclear fuel . The treaty promotes the peaceful use of nuclear fuel , as well as limiting the spread of nuclear weapons . A typical nuclear reactor uses about 200 tons of uranium every year. Complex processes allow some uranium and plutonium to be re-enriched or recycled . This reduces the amount of mining , extracting , and processing that needs to be done. Nuclear Energy and People Nuclear energy produces electricity that can be used to power homes, schools, businesses, and hospitals. The first nuclear reactor to produce electricity was located near Arco, Idaho. The Experimental Breeder Reactor began powering itself in 1951. The first nuclear power plant designed to provide energy to a community was established in Obninsk, Russia, in 1954. Building nuclear reactors requires a high level of technology , and only the countries that have signed the Nuclear Non-Proliferation Treaty can get the uranium or plutonium that is required. For these reasons, most nuclear power plants are located in the developed world. Nuclear power plants produce renewable, clean energy . They do not pollute the air or release  greenhouse gases . They can be built in urban or rural areas , and do not radically alter the environment around them. The steam powering the turbines and generators is ultimately recycled . It is cooled down in a separate structure called a cooling tower . The steam turns back into water and can be used again to produce more electricity . Excess steam is simply recycled into the atmosphere , where it does little harm as clean water vapor . However, the byproduct of nuclear energy is radioactive material. Radioactive material is a collection of unstable atomic nuclei . These nuclei lose their energy and can affect many materials around them, including organisms and the environment. Radioactive material can be extremely toxic , causing burns and increasing the risk for cancers , blood diseases, and bone decay .

Radioactive waste is what is left over from the operation of a nuclear reactor . Radioactive waste is mostly protective clothing worn by workers, tools, and any other material that have been in contact with radioactive dust. Radioactive waste is long-lasting. Materials like clothes and tools can stay radioactive for thousands of years. The government regulates how these materials are disposed of so they don't contaminate anything else. Used fuel and rods of nuclear poison are extremely radioactive . The used uranium pellets must be stored in special containers that look like large swimming pools. Water cools the fuel and insulates the outside from contact with the radioactivity. Some nuclear plants store their used fuel in dry storage tanks above ground. The storage sites for radioactive waste have become very controversial in the United States. For years, the government planned to construct an enormous nuclear waste facility near Yucca Mountain, Nevada, for instance. Environmental groups and local citizens protested the plan. They worried about radioactive waste leaking into the water supply and the Yucca Mountain environment, about 130 kilometers (80 miles) from the large urban area of Las Vegas, Nevada. Although the government began investigating the site in 1978, it stopped planning for a nuclear waste facility in Yucca Mountain in 2009. Chernobyl Critics of nuclear energy worry that the storage facilities for radioactive waste will leak, crack, or erode . Radioactive material could then contaminate the soil and groundwater near the facility . This could lead to serious health problems for the people and organisms in the area. All communities would have to be evacuated . This is what happened in Chernobyl, Ukraine, in 1986. A steam explosion at one of the power plants four nuclear reactors caused a fire, called a plume . This plume was highly radioactive , creating a cloud of radioactive particles that fell to the ground, called fallout . The fallout spread over the Chernobyl facility , as well as the surrounding area. The fallout drifted with the wind, and the particles entered the water cycle as rain. Radioactivity traced to Chernobyl fell as rain over Scotland and Ireland. Most of the radioactive fallout fell in Belarus.

The environmental impact of the Chernobyl disaster was immediate . For kilometers around the facility , the pine forest dried up and died. The red color of the dead pines earned this area the nickname the Red Forest . Fish from the nearby Pripyat River had so much radioactivity that people could no longer eat them. Cattle and horses in the area died. More than 100,000 people were relocated after the disaster , but the number of human victims of Chernobyl is difficult to determine . The effects of radiation poisoning only appear after many years. Cancers and other diseases can be very difficult to trace to a single source. Future of Nuclear Energy Nuclear reactors use fission, or the splitting of atoms , to produce energy. Nuclear energy can also be produced through fusion, or joining (fusing) atoms together. The sun, for instance, is constantly undergoing nuclear fusion as hydrogen atoms fuse to form helium . Because all life on our planet depends on the sun, you could say that nuclear fusion makes life on Earth possible. Nuclear power plants do not have the capability to safely and reliably produce energy from nuclear fusion . It's not clear whether the process will ever be an option for producing electricity . Nuclear engineers are researching nuclear fusion , however, because the process will likely be safe and cost-effective.

Nuclear Tectonics The decay of uranium deep inside the Earth is responsible for most of the planet's geothermal energy, causing plate tectonics and continental drift.

Three Mile Island The worst nuclear accident in the United States happened at the Three Mile Island facility near Harrisburg, Pennsylvania, in 1979. The cooling system in one of the two reactors malfunctioned, leading to an emission of radioactive fallout. No deaths or injuries were directly linked to the accident.

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• ENVIRONMENT

What is nuclear energy and is it a viable resource?

Nuclear energy's future as an electricity source may depend on scientists' ability to make it cheaper and safer.

Nuclear power is generated by splitting atoms to release the energy held at the core, or nucleus, of those atoms. This process, nuclear fission, generates heat that is directed to a cooling agent—usually water. The resulting steam spins a turbine connected to a generator, producing electricity.

About 450 nuclear reactors provide about 11 percent of the world's electricity. The countries generating the most nuclear power are, in order, the United States, France, China, Russia, and South Korea.

The most common fuel for nuclear power is uranium, an abundant metal found throughout the world. Mined uranium is processed into U-235, an enriched version used as fuel in nuclear reactors because its atoms can be split apart easily.

In a nuclear reactor, neutrons—subatomic particles that have no electric charge—collide with atoms, causing them to split. That collision—called nuclear fission—releases more neutrons that react with more atoms, creating a chain reaction. A byproduct of nuclear reactions, plutonium , can also be used as nuclear fuel.

Types of nuclear reactors

In the U.S. most nuclear reactors are either boiling water reactors , in which the water is heated to the boiling point to release steam, or pressurized water reactors , in which the pressurized water does not boil but funnels heat to a secondary water supply for steam generation. Other types of nuclear power reactors include gas-cooled reactors, which use carbon dioxide as the cooling agent and are used in the U.K., and fast neutron reactors, which are cooled by liquid sodium.

Nuclear energy history

The idea of nuclear power began in the 1930s , when physicist Enrico Fermi first showed that neutrons could split atoms. Fermi led a team that in 1942 achieved the first nuclear chain reaction, under a stadium at the University of Chicago. This was followed by a series of milestones in the 1950s: the first electricity produced from atomic energy at Idaho's Experimental Breeder Reactor I in 1951; the first nuclear power plant in the city of Obninsk in the former Soviet Union in 1954; and the first commercial nuclear power plant in Shippingport, Pennsylvania, in 1957. ( Take our quizzes about nuclear power and see how much you've learned: for Part I, go here ; for Part II, go here .)

Nuclear power, climate change, and future designs

Nuclear power isn't considered renewable energy , given its dependence on a mined, finite resource, but because operating reactors do not emit any of the greenhouse gases that contribute to global warming , proponents say it should be considered a climate change solution . National Geographic emerging explorer Leslie Dewan, for example, wants to resurrect the molten salt reactor , which uses liquid uranium dissolved in molten salt as fuel, arguing it could be safer and less costly than reactors in use today.

Others are working on small modular reactors that could be portable and easier to build. Innovations like those are aimed at saving an industry in crisis as current nuclear plants continue to age and new ones fail to compete on price with natural gas and renewable sources such as wind and solar.

The holy grail for the future of nuclear power involves nuclear fusion, which generates energy when two light nuclei smash together to form a single, heavier nucleus. Fusion could deliver more energy more safely and with far less harmful radioactive waste than fission, but just a small number of people— including a 14-year-old from Arkansas —have managed to build working nuclear fusion reactors. Organizations such as ITER in France and Max Planck Institute of Plasma Physics are working on commercially viable versions, which so far remain elusive.

Nuclear power risks

When arguing against nuclear power, opponents point to the problems of long-lived nuclear waste and the specter of rare but devastating nuclear accidents such as those at Chernobyl in 1986 and Fukushima Daiichi in 2011 . The deadly Chernobyl disaster in Ukraine happened when flawed reactor design and human error caused a power surge and explosion at one of the reactors. Large amounts of radioactivity were released into the air, and hundreds of thousands of people were forced from their homes . Today, the area surrounding the plant—known as the Exclusion Zone—is open to tourists but inhabited only by the various wildlife species, such as gray wolves , that have since taken over .

In the case of Japan's Fukushima Daiichi, the aftermath of the Tohoku earthquake and tsunami caused the plant's catastrophic failures. Several years on, the surrounding towns struggle to recover, evacuees remain afraid to return , and public mistrust has dogged the recovery effort, despite government assurances that most areas are safe.

Other accidents, such as the partial meltdown at Pennsylvania's Three Mile Island in 1979, linger as terrifying examples of nuclear power's radioactive risks. The Fukushima disaster in particular raised questions about safety of power plants in seismic zones, such as Armenia's Metsamor power station.

Other issues related to nuclear power include where and how to store the spent fuel, or nuclear waste, which remains dangerously radioactive for thousands of years. Nuclear power plants, many of which are located on or near coasts because of the proximity to water for cooling, also face rising sea levels and the risk of more extreme storms due to climate change.

For Hungry Minds

Related topics.

• NUCLEAR ENERGY
• NUCLEAR WEAPONS
• TOXIC WASTE
• RENEWABLE ENERGY

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The next generation of nuclear reactors is getting more advanced. Here’s how.

Alternative ways of powering, cooling, and constructing reactors could help get more nuclear energy on the grid.

• Casey Crownhart archive page

This article is from The Spark, MIT Technology Review ’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here .

I’ve got nuclear power on the brain this week. 

The workings of nuclear power plants have always fascinated me. They’re massive, technically complicated, and feel a little bit magic (splitting the atom—what a concept). But I’ve reached new levels of obsession recently, because I’ve spent the past week or so digging into advanced nuclear technology. 

Advanced nuclear is a mushy category that basically includes anything different from the commercial reactors operating now, since those basically all follow the same general formula. And there’s a whole world of possibilities out there. 

I was mostly focused on the version that’s being developed by Kairos Power for a story (which was published today, check it out if you haven’t! ). But I went down some rabbit holes on other potential options for future nuclear plants too. So for the newsletter this week, let’s take a peek at the menu of options for advanced nuclear technology today. 

Before we get into the advanced stuff, let’s recap the basics.

Nuclear power plants generate electricity via fission reactions , where atoms split apart, releasing energy as heat and radiation. Neutrons released during these splits collide with other atoms and split them, creating a chain reaction.

In nuclear power plants today, there are basically two absolutely essential pieces. First, the fuel, which is what feeds the reactions. (Pretty obvious why this one is important.) Second, it’s vital that the chain reactions happen in a controlled manner, or you can get into nuclear meltdown territory. So the other essential piece of a nuclear plant is the cooling system, which keeps the whole thing from getting too hot and causing problems. (There’s also the moderator and a million other pieces, but let’s stick with two so you’re not reading this newsletter all day.)

In the vast majority of reactors on the grid today, these two components follow the same general formula : the fuel is enriched uranium that’s packed into ceramic pellets, loaded into metal pipes, and arranged into the reactor’s core. And the cooling system pumps pressurized water around the reactor to keep the temperature controlled.  

But for a whole host of reasons, companies are starting to work on making changes to this tried-and-true formula. There are roughly 70 companies in the US working on designs for advanced nuclear reactors, with six or seven far enough along to be working with regulators, says Jessica Lovering , cofounder and co-executive director at the Good Energy Collective, a policy research organization that advocates for the use of nuclear energy.

Many of these so-called advanced technologies were invented and even demonstrated over 50 years ago, before the industry converged on the standard water-cooled plant designs. But now there’s renewed interest in getting alternative nuclear reactors up and running. New designs could help improve safety, efficiency, and even cost. 

Alternative coolants can improve on safety over water-based designs, since they don’t always need to be kept at high pressures. Many can also reach higher temperatures, which can allow reactors to run more efficiently. 

Molten salt is one leading contender for alternative coolants, used in designs from Kairos Power, Terrestrial Energy , and Moltex Energy . These designs can use less fuel and produce waste that’s easier to manage. 

Other companies are looking to liquid metals , including sodium and lead. There are a few sodium-cooled reactors operating today, mainly in Russia, and the country is also at the forefront in developing lead-cooled reactors. Metal-cooled reactors share many of the potential safety benefits of molten-salt designs. Helium and other gases can also be used to reach higher temperatures than water-cooled systems. X-energy is designing a high-temperature gas-cooled reactor using helium. 

Most reactors that use an alternative coolant also use an alternative fuel.  

TRISO, or tri-structural isotropic particle fuel, is one of the most popular options. TRISO particles contain uranium, enclosed in ceramic and carbon-based layers. This keeps the fuel contained, keeping all the products of fission reactions inside and allowing the fuel to resist corrosion and melting. Kairos and X-energy both plan to use TRISO fuel in their reactors. 

Other reactors use HALEU : high-assay low-enriched uranium . Most nuclear fuel used in commercial reactors contains between 3% and 5% uranium-235. HALEU, on the other hand, contains between 5% and 20% uranium-235, allowing reactors to get more power in a smaller space. 

I know I said I’d keep this to two things, but let’s include a bonus category. In addition to changing up the specifics of things like fuel and coolant, many companies are working to build reactors of different (mostly smaller) sizes.

Today, most reactors coming on the grid are massive, in the range of 1,000 or more megawatts—enough to power hundreds of thousands of homes. Building those huge projects takes a long time, and each one requires a bespoke process. Small modular reactors (SMRs) could be easier to build, since the procedure is the same for each one, allowing them to be manufactured in something resembling a huge assembly line. 

NuScale has been one of the leaders in this area—its reactor design uses commercial fuel and water coolant, but the whole thing is scaled down. Things haven’t been going so well for the company in recent months, though: its first project is pretty much dead in the water , and it laid off nearly 30% of its employees in early January. Other companies are still carrying the SMR torch, including many that are also going after alternative fuels and coolants. 

If you’re hungry for more advanced nuclear news, take a look at my story on Kairos Power . You can also check out some of our recent stories from the vault. 

Related reading

Germany shut down the last of its nuclear reactors last year. Here’s a look at the power struggle over nuclear power in the country.

MIT runs a small test reactor on campus, and I got to take a look inside. See how this old reactor could spark new technology.

We were promised smaller nuclear reactors, but so far that promise hasn't really materialized. What gives?

We named NuScale one of our Climate Tech Companies to Watch in 2023 . We’re definitely … watching, given the recent bumps in the road. 

Another thing

Super-efficient solar cells are on our list of the 10 Breakthrough Technologies of 2024. (If you haven’t seen that list, you can find it here !) By sandwiching other materials with traditional silicon, tandem perovskite solar cells could help cut solar costs and generate more electricity. 

But what will it actually take to get next-generation solar technology to the market? Here’s a look at a few of the companies working to make it happen.

Keeping up with climate  

Hertz was billing itself as a leader in renting out electric vehicles (remember that Tom Brady commercial ?). Now the company is selling off a third of its EV fleet. ( Tech Crunch )

A mountain of clothes accumulated in the desert in Chile. Then it caught fire. This is a fascinating deep dive into the problem of textile waste. ( Grist )

New uranium mines will be the first to begin operations in the US in eight years. The mines could help bring more low-carbon nuclear power to the grid, but they’re also drawing sharp criticism. ( Inside Climate News )

Researchers at Microsoft and a US national lab used AI to find a new candidate material for batteries. It could eventually be used in batteries to reduce the amount of lithium needed to build them. ( The Verge )

→ I talked about this and other science news of the week on Science Friday. Give it a listen! ( Science Friday )

Animals are always evolving. A few lucky ones might even be able to do it fast enough to keep up with climate change. ( Hakai Magazine )

All that new renewable energy coming onto the grid is helping make a dent in US emissions. Buildout of clean energy cut greenhouse-gas emissions by nearly 2% in 2023. ( Canary Media )

The Biden administration will fine oil and gas companies for excess methane emissions. Penalties for emitting this super-powerful greenhouse gas are part of the landmark climate bill passed in 2023. ( New York Times )

Climate change and energy

The problem with plug-in hybrids their drivers..

Plug-in hybrids are often sold as a transition to EVs, but new data from Europe shows we’re still underestimating the emissions they produce.

These artificial snowdrifts protect seal pups from climate change

The human-built habitats shield the pups from predators and the freezing cold, but they’re threatened by global temperature rise.

• Matthew Ponsford archive page

How thermal batteries are heating up energy storage

The systems, which can store clean energy as heat, were chosen by readers as the 11th Breakthrough Technology of 2024.

The hard lessons of Harvard’s failed geoengineering experiment

Some observers argue the end of SCoPEx should mark the end of such proposals. Others say any future experiments should proceed in markedly different ways.

• James Temple archive page

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Scientists Achieve Nuclear Fusion Breakthrough With Blast of 192 Lasers

The advancement by Lawrence Livermore National Laboratory researchers will be built on to further develop fusion energy research.

By Kenneth Chang

Scientists studying fusion energy at Lawrence Livermore National Laboratory in California announced on Tuesday that they had crossed a long-awaited milestone in reproducing the power of the sun in a laboratory.

That sparked public excitement as scientists have for decades talked about how fusion, the nuclear reaction that makes stars shine, could provide a future source of bountiful energy.

The result announced on Tuesday is the first fusion reaction in a laboratory setting that actually produced more energy than it took to start the reaction.

“This is such a wonderful example of a possibility realized, a scientific milestone achieved, and a road ahead to the possibilities for clean energy,” Arati Prabhakar, the White House science adviser, said during a news conference on Tuesday morning at the Department of Energy’s headquarters in Washington, D.C. “And even deeper understanding of the scientific principles that are applied here.”

If fusion can be deployed on a large scale, it would offer an energy source devoid of the pollution and greenhouse gases caused by the burning of fossil fuels and the dangerous long-lived radioactive waste created by current nuclear power plants, which use the splitting of uranium to produce energy.

Within the sun and stars, fusion continually combines hydrogen atoms into helium, producing sunlight and warmth that bathes the planets. In experimental reactors and laser labs on Earth, fusion lives up to its reputation as a very clean energy source.

There was always a nagging caveat, however. In all of the efforts by scientists to control the unruly power of fusion, their experiments consumed more energy than the fusion reactions generated.

That changed at 1:03 a.m. on Dec. 5 when 192 giant lasers at the laboratory’s National Ignition Facility blasted a small cylinder about the size of a pencil eraser that contained a frozen nubbin of hydrogen encased in diamond.

The laser beams entered at the top and bottom of the cylinder, vaporizing it. That generated an inward onslaught of X-rays that compresses a BB-size fuel pellet of deuterium and tritium, the heavier forms of hydrogen.

In a brief moment lasting less than 100 trillionths of a second, 2.05 megajoules of energy — roughly the equivalent of a pound of TNT — bombarded the hydrogen pellet. Out flowed a flood of neutron particles — the product of fusion — which carried about 3 megajoules of energy, a factor of 1.5 in energy gain.

This crossed the threshold that laser fusion scientists call ignition, the dividing line where the energy generated by fusion equals the energy of the incoming lasers that start the reaction.

“You see one diagnostic and you think maybe that’s not real and then you start to see more and more diagnostics rolling in, pointing to the same thing,” said Annie Kritcher, a physicist at Livermore who described reviewing the data after the experiment. “It’s a great feeling.”

The successful experiment finally delivers the ignition goal that was promised when construction of the National Ignition Facility started in 1997. When operations began in 2009, however, the facility hardly generated any fusion at all, an embarrassing disappointment after a $3.5 billion investment from the federal government.

In 2014, Livermore scientists finally reported some success , but the energy produced was minuscule — the equivalent of what a 60-watt light bulb consumes in five minutes. Progress over the next few years was slight and small.

Then, in August last year, the facility produced a much larger burst of energy — 70 percent as much energy as the laser light energy.

In an interview, Mark Herrmann, program director for weapons physics and design at the Livermore, said the researchers then performed a series of experiments to better understand the surprising August success, and they worked to bump up the energy of lasers by almost 10 percent and improve the design of the hydrogen targets.

The first laser shot at 2.05 megajoules was performed in September, and that first try produced 1.2 megajoules of fusion energy. Moreover, analysis showed that the spherical pellet of hydrogen was not squeezed evenly, and some of the hydrogen essentially squirted out the side and did not reach fusion temperatures.

The scientists made some adjustments that they believed would work better.

“The prediction ahead of the shot was that it could go up a factor of two,” Dr. Herrmann said. “In fact, it went up a little more than that.”

The main purpose of the National Ignition Facility is to conduct experiments to help the United States maintain its nuclear weapons. That makes the immediate implications for producing energy tentative.

Fusion would be essentially an emissions-free source of power, and it would help reduce the need for power plants burning coal and natural gas, which pump billions of tons of planet-warming carbon dioxide into the atmosphere each year.

But it will take quite a while before fusion becomes available on a widespread, practical scale, if ever.

“Probably decades,” Kimberly S. Budil, the director of Lawrence Livermore, said during the Tuesday news conference. “Not six decades, I don’t think. I think not five decades, which is what we used to say. I think it’s moving into the foreground and probably, with concerted effort and investment, a few decades of research on the underlying technologies could put us in a position to build a power plant.”

Most climate scientists and policymakers say that to achieve that goal of limiting warming to 2 degrees Celsius, or the even more ambitious target of 1.5 degrees Celsius of warming, the world must reach net-zero emissions by 2050.

Fusion efforts to date have primarily used doughnut-shaped reactors known as tokamaks. Within the reactors, hydrogen gas is heated to temperatures hot enough that the electrons are stripped away from the hydrogen nuclei, creating what is known as a plasma — clouds of positively charged nuclei and negatively charged electrons. Magnetic fields trap the plasma within the doughnut shape, and the nuclei fuse together, releasing energy in the form of neutrons flying outward.

The work at NIF takes a different approach, but so far, little work has gone into turning the idea of a laser fusion power plant into reality. “There are very significant hurdles, not just in the science, but in technology,” Dr. Budil said.

NIF is the world’s most powerful laser, but it is a slow and inefficient one, relying on decades-old technology.

The apparatus, about the size of a sports stadium, is designed to perform basic science experiments, not serve as a prototype for the generation of electricity.

It averages about 10 shots per week. A commercial facility using the laser fusion approach would need much faster lasers, able to shoot at a machine-gun pace, perhaps 10 times a second.

NIF also still consumes far more energy than is produced by the fusion reactions.

Although the latest experiment produced a net energy gain compared to the energy of the 2.05 megajoules in the incoming laser beams, NIF needed to pull 300 megajoules of energy from the electrical grid in order to generate the brief laser pulse.

Other types of lasers are more efficient, but experts say a viable laser fusion power plant would likely require much higher energy gains than the 1.5 observed in this latest fusion shot.

“You’ll need gains of 30 to 100 in order to get more energy for an energy power plant,” Dr. Herrmann said.

He said Livermore would continue to push NIF fusion experiments to higher fusion output.

“That’s really what we’re going to be looking at honestly over the next few years,” Dr. Herrmann said. “These experiments show that even a little bit more laser energy can make a big difference.”

Researchers elsewhere are looking at variations of the NIF experiment. Other types of lasers at different wavelengths might heat the hydrogen more efficiently.

Some researchers favor a “direct drive” approach to laser fusion, using the laser light to directly heat the hydrogen. That would get more energy into the hydrogen, but could also create instabilities that thwart the fusion reactions.

In March, the White House held a summit to seek to accelerate commercial fusion efforts.

“Developing an economically attractive approach to fusion energy is a grand scientific and engineering challenge,” Tammy Ma, who leads an effort at Livermore to study the possibilities. “Without a doubt, it will be a monumental undertaking.”

Dr. Ma said that a report commissioned by the energy department to provide a framework for laser fusion energy research would come out soon.

“Such a program,” she said, “will inevitably require participation from across the community,” including academia, start-up companies and public utilities in addition to national laboratories like Livermore.

The results announced Tuesday will benefit the scientists working on the nuclear stockpile, the NIF’s primary purpose. By performing these nuclear reactions in a lab at a less destructive scale, scientists aim to replace the data they used to gather from underground nuclear bomb detonations, which the United States stopped in 1992.

The greater fusion output from the facility will produce more data “that allows us to maintain the confidence in our nuclear deterrent without the need for further underground testing,” Dr. Herrmann said. “The output, that 30,000 trillion watts of power, creates very extreme environments in itself” that more closely resemble an exploding nuclear weapon.

Riccardo Betti, chief scientist of the Laboratory for Laser Energetics at the University of Rochester, who was not involved with this particular Livermore experiment, said, “This is the goal, to demonstrate that one can ignite a thermonuclear fuel in the laboratory for the first time.”

“And this was done,” he added. “So this is a great result.”

Henry Fountain and Zach Montague contributed reporting.

An earlier version of this article misstated the month in which the White House held a fusion summit. It was March, not April.

How we handle corrections

Kenneth Chang has been at The Times since 2000, writing about physics, geology, chemistry, and the planets. Before becoming a science writer, he was a graduate student whose research involved the control of chaos. More about Kenneth Chang

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Growing share of Americans favor more nuclear power

As the first new U.S. nuclear power reactor since 2016 begins operations, more Americans now say they favor expanding nuclear power in the United States than a few years ago, according to a recent Pew Research Center survey .

To measure public attitudes in the United States toward the use of nuclear power, we analyzed data from a survey of 10,329 U.S. adults conducted from May 30 to June 4, 2023. Everyone who took part in the survey is a member of the Pew Research Center’s American Trends Panel (ATP), an online survey panel that is recruited through national, random sampling of residential addresses. This way, nearly all U.S. adults have a chance of selection. The survey is weighted to be representative of the U.S. adult population by gender, race, ethnicity, partisan affiliation, education and other categories. Read more about the ATP’s methodology . Here are the questions used for the analysis , along with responses, and its methodology .

This post also incorporates findings from a Center survey of 10,701 U.S. adults conducted March 13-19, 2023. Here are the questions used in that survey , along with responses, and its methodology .

We tracked the number of U.S. nuclear power reactors over time by analyzing data from the International Atomic Energy Agency’s (IAEA) Power Reactor Information System . The IAEA classifies a reactor as “operational” from the date of its first electrical grid connection to the date of its permanent shutdown. Reactors that face temporary outages are still categorized as operational. Annual totals exclude reactors that closed that year.

A majority of Americans (57%) say they favor more nuclear power plants to generate electricity in the country, up from 43% who said this in 2020.

Americans are still far more likely to say they favor more solar power (82%) and wind power (75%) than nuclear power. All three energy sources emit no carbon.

Advocates for nuclear power argue it could play a crucial role in reducing carbon emissions from electricity generation. Critics highlight the high cost of nuclear power plant projects and the complexities of handling radioactive waste.

Support for nuclear power has increased among both parties since 2020. Half of Democrats and Democratic-leaning independents now say they favor expanding nuclear power, an increase from 37% in 2020. And two-thirds of Republicans and Republican leaners now favor more nuclear power, up 14 percentage points since 2020, when 53% said they support more nuclear power.

When asked about the federal government’s role, 41% of Americans say it should encourage the production of nuclear power. Some 22% think the federal government should discourage the production of nuclear power, and 36% think it should neither encourage nor discourage it. The share of Americans who think the federal government should encourage nuclear power production is up 6 points from last year.

Still, a far larger share of Americans think the federal government should encourage the production of wind and solar power (66%).

Gender, partisan differences in views of nuclear power

Attitudes on nuclear power production have long differed by gender and party affiliation.

Men are about twice as likely as women to say the federal government should encourage the production of nuclear power (54% vs. 28%). Similarly, men are far more likely than women to favor more nuclear power plants to generate electricity (71% vs. 44%).

Views differ by gender globally , too, according to a Center survey conducted from fall 2019 to spring 2020. In 18 of the 20 survey publics, men were more likely than women to favor using more nuclear power as a source of domestic energy.

In the U.S., Republicans are more likely than Democrats to favor more nuclear power and to say the federal government should encourage its production.

Two-thirds of Republicans say they favor more nuclear power plants to generate electricity, compared with half of Democrats.

Republicans have supported nuclear power expansion in greater shares than Democrats each time this question has been asked since 2016.

The 17-point partisan difference on nuclear power is smaller than those for other energy sources, including fossil fuel sources such as offshore oil and gas drilling (48 points) and coal mining (47 points).

A look at U.S. nuclear power reactors

The U.S. currently has 93 nuclear power reactors , plus one that’s under construction in Georgia . These reactors collectively generated 18.2% of all U.S. electricity in 2022 , according to the U.S. Energy Information Administration.

Half (47) of the United States’ nuclear power reactors are in the South, while about a quarter (22) are in the Midwest. There are 18 reactors in the Northeast and six in the West, according to data from the International Atomic Energy Agency (IAEA).

The number of U.S. reactors has steadily fallen since peaking at 111 in 1990. Nine Mile Point-1, located in Scriba, New York, is the oldest U.S. nuclear power reactor still in operation. It was first connected to the power grid in November 1969. Most of the 93 current reactors began operations in the 1970s (41 reactors) or 1980s (44), according to data from the IAEA. (The IAEA classifies reactors as “operational” from their first electrical grid connection to their date of permanent shutdown.)

One of the many reasons nuclear power projects have dwindled in recent decades may be perceived dangers following nuclear accidents in the U.S. and abroad. For example, the 2011 Fukushima Daiichi accident led the Japanese government to greatly decrease its reliance on nuclear power and prompted other countries to rethink their nuclear energy plans . More recently, Russian military attacks in Ukraine have raised fears of nuclear power plant accidents in the area.

Note: Here are the questions used for the analysis , along with responses, and its methodology . This is an update of a post first published March 23, 2022.

• Climate, Energy & Environment

Rebecca Leppert is a copy editor at Pew Research Center .

Brian Kennedy is a senior researcher focusing on science and society research at Pew Research Center .

How Republicans view climate change and energy issues

How americans view future harms from climate change in their community and around the u.s., americans continue to have doubts about climate scientists’ understanding of climate change, why some americans do not see urgency on climate change, what the data says about americans’ views of climate change, most popular.

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Addressing Texas grid reliability: Time to go nuclear?

May 13, 2024

By Texas summer standards, the heat in August 2023 seemed relentless but not without precedent. A string of 100-plus-degree days gripped the state, and the sound of air conditioning was constant.

The overseer of much of the state’s electricity grid, the Electric Reliability Council of Texas (ERCOT), issued eight conservation appeals during the month, encouraging retail electricity customers to reduce use of air conditioning and large appliances. Some days it was barely enough. Output from solar and wind facilities was low while thermal energy sources (natural gas, coal and nuclear) struggled to keep up with record-setting electricity demand, or load.

As the energy capital of the nation kept a wary eye on power reserves, ERCOT officials warned they might need to resort to rolling blackouts to keep the system from breaking.

In recent years, low-cost renewable energy sources such as wind and solar have flourished. However, when the wind doesn’t blow or the sun doesn’t shine, and there are inadequate thermal resources to fill the gap, the grid can become vulnerable.

An expanding economy and population, a growing footprint of manufacturing facilities and data centers and more frequent episodes of extreme heat and cold have contributed to Texas electricity consumption rising at an annual rate exceeding the national average.

Nuclear power advocates say that at a time of increasing use of renewables and heightened concerns over climate change, nuclear should become a more readily available part of the mix. Nuclear is reliable, energy dense and scalable. It also has zero carbon emissions. Comanche Peak Nuclear Power Plant No. 2 in Glen Rose, Texas, 85 miles southwest of Dallas, began operations in 1993. Since then, no other nuclear power plant has opened in the state.

Share of renewable energy triples

The share of renewables for Texas’ overall electricity consumption tripled from 2010 to 2023, a product of federal tax credits, falling installation and materials costs, bountiful wind and solar resources, and state-incentive-backed transmission capacity growth. Wind and solar accounted for roughly one-third of electricity produced in 2023 ( Chart 1 ).

Downloadable chart

However, this does not mean renewables supplied nearly a third of energy needs every day. Renewables present a unique set of challenges to managing the power grid, including a frequent mismatch between peak load and peak supply.

As load peaks in the early evening during the summer, solar production declines, forcing natural gas-fired generation plants to rapidly increase output ( Chart 2 ). The reverse occurs in the early morning, when gas facilities ramp up (as households start their day) and trail off as solar output emerges with the rising sun.

Similarly, load follows an uneven pattern on the coldest winter days, again not aligning well with the timing of solar output and often prompting the need for gas plants to ramp up quickly. ( Chart 3 ).

Meanwhile, wind also presents resource availability challenges. When the wind doesn’t blow, the enormous and growing level of installed wind capacity is unavailable, and another power source has to take its place. Such uneven cycles on gas plants accelerate wear on the facilities, contributing to unplanned outages and maintenance downtime.

The thinning margin between thermal plant capacity and peak load has produced periods of high and volatile wholesale electricity prices across the state. Statewide wholesale electricity prices, which typically average below $100 per megawatt-hour, shot past $1,000 per megawatt-hour 15 times during summer 2021. Prices crossed the $1,000 threshold 182 times in summer 2023 with the greater prevalence of renewables and ERCOT’s cautious power reserve management.

These conditions have also created an opportunity during peak load periods for utility-scale batteries, whose capacity in Texas soared over the past two years. Battery technology is uniquely suited to discharge during critical periods, when solar and wind output fades. However, the current state of technology prevents their use as a source of baseload power, that is, dependably available and capable of running 24 hours a day, seven days a week.

Keeping the grid running 

Nuclear provides a minor portion of Texas’ current generating portfolio. Texas’ two nuclear plants, combining for more than 5 gigawatts of nameplate (or total) output, fulfill the role of baseload power. To put that capacity in perspective, the state has 22 gigawatts of installed solar capacity and more than 38 gigawatts of installed wind capacity.  

Conventional light-water nuclear reactors are not well equipped to meet the flexible energy needs of a grid with robust intermittent resources, since reactors are not designed to ramp up or down quickly in response to demand. A significant expansion of conventional nuclear capacity would increase the steady baseload supporting the electric grid and reduce the amplitude of the daily power demand cycle currently required of natural gas plants.

However, new nuclear facility developers confront high costs, regulatory requirements and pockets of public opposition.

While fuel and operating costs for conventional nuclear plants are relatively inexpensive, construction costs are enormous and the federal permitting process stretches over several years while billions of dollars in expenses are incurred, making cost recovery highly uncertain. Expansion of Plant Vogtle in Georgia, completed in 2023, marked the first nuclear reactor to receive regulatory approval in 30 years. It was seven years late and $17 billion over budget.

When considering capital costs, nuclear appears uncompetitive compared with alternatives. The financial advisory firm Lazard found the unsubsidized levelized cost of energy for a nuclear plant can be more than twice that of a combined-cycle natural gas plant, one that generates electricity from both primary generation and from converting waste steam to power. (Levelized cost is the net present cost over the lifetime of a generating facility, generally spanning 30 to 50 years).

In a reversal of long-term trends, public support in the U.S. for nuclear has increased over the past decade, with a narrow majority supporting it. Opponents remain fearful of risks following incidents such as the Fukushima Daiichi accident , when a Japanese power plant released radioactive material following an earthquake in March 2011.

As aging U.S. power generation facilities face rounds of permit extensions at state and federal levels, 12 reactors nationwide have been decommissioned over the past 10 years, most in response to local opposition.

Small modular reactors among new technologies

Despite barriers to approval, nuclear backers cite the power source’s carbon-free operations, reliability, generation capacity and energy density. Development of advanced nuclear reactor technology may address many of the challenges that have stymied growth of conventional nuclear. 

The Department of Energy launched its Advanced Reactor Demonstration Program in 2020 to aid nuclear research and development in the hope of spurring new technology, including smaller and more flexible nuclear reactor options. The program has since announced multiyear awards totaling about $4.6 billion to three projects, including a demonstration project planned for Texas. 

The Texas effort, expected to be completed by 2030, involves small modular reactors. Such units can be manufactured at one site then shipped and assembled at the point of use. A site can start hosting one module and add additional modules, allowing long-term scalability.

Typically, a small modular reactor has up to 300 megawatts of capacity and requires far less acreage than a traditional large reactor. Some designs are expected to be more flexible and should have the ability to ramp up and down to meet shifting load requirements, unlike conventional units.

One of the promises of the modular reactors is far lower upfront capital investment than conventional nuclear facilities. But there are concerns that the modular reactors may not be as cost effective as imagined, and cost per megawatt remains high compared with fossil fuel generation. In November 2023, another demonstration program fund recipient canceled its project, citing significant increases in previously projected costs.

While much of the cost increase can be attributed to inflation that plagued many infrastructure programs in 2023, concerns remain about the cost/benefit of modular reactors in Texas and elsewhere.

Management of nuclear waste is another challenge. Annually, traditional nuclear reactors in the U.S. produce about 2,000 metric tons of spent fuel in the aggregate, which is currently stored at the power plants in temporary pools or dry casks .

The long-term goal is permanent storage at an approved, central geologic repository, but progress on site selection has been at a standstill for two decades. Although modular reactors would likely produce far less spent fuel, concerns have surfaced that some units would create many more times the amount of spent fuel per unit of electricity generated than traditional reactors. 

In addition to the federal efforts to spur advanced nuclear deployment, Texas Gov. Greg Abbott announced the formation of the Advanced Nuclear Reactor Working Group in 2023. The group is charged with assessing the feasibility of making the state a leader in nuclear power. With a team comprised of academics, business leaders and nuclear engineering experts, the working group seeks to understand how advancements such as modular reactors can be leveraged to improve affordability, reliability and safety in Texas’ energy sector. Results from their evaluation will be announced in December 2024.

Texas may also prove fertile ground for modular reactor deployment for industrial uses. The modular reactors may be particularly suited to serve on-site at the large and growing footprint of heavy manufacturing, petrochemical facilities and data centers. The first units—already ordered—are likely to appear toward the end of the decade.

Balancing costs and reliability

While developments in advanced nuclear technology hold promise for an energy grid to achieve a desired balance of low emissions and reliability, affordability may remain elusive. Additionally, widespread deployment of advanced nuclear is at least a decade away. Balancing electricity supply and demand with solar, wind, batteries and natural gas resources—and the associated price volatility for consumers—will remain a significant challenge in the interim.    

ERCOT’s electricity load set records in summer 2023, primarily because of consistently excessive heat. In the winter, the grid continues to face challenges, especially during sustained temperature drops, which spike demand across the state and impact the natural gas supply chain.

Even though wholesale electricity prices rise sharply during periods of tight supply and demand , most households don’t experience surging power bills because they have fixed-rate power contracts. However, volatile prices and rising load forecasts have increased forward electricity prices, which pushes retail prices higher over time. While the residential cost per kilowatt-hour in Texas ranged between 14 and 17 cents from 2015 to 2019 in real (inflation-adjusted) terms, it jumped to more than 30 cents in 2022 and has remained volatile since ( Chart 4 ).

For low-income households struggling to get by, rising utility bills represent a significant share of living expenses. For example, in 2023, 57 percent of Texas households with annual income under $50,000 reported forgoing meals or medication to pay energy bills.

In times of severe weather, such households may also be at particular risk of power loss. During the February 2021 statewide freeze, communities with higher shares of racial minorities were more than four times more likely than predominately white areas to experience blackouts, driving some to unsafe heating methods that led to carbon monoxide poisoning .

Charting a path forward

Nuclear energy offers several advantages over other types of power: It is cleaner than fossil fuels, it is more predictable and reliable than renewables, and its generation capacity is far greater than all alternatives. Nuclear reactors in Texas, either at the utility level or as co-generation assets for heavy manufacturing facilities, offer the prospect of solving many fundamental challenges for the grid.

However, significant upfront capital costs mean the returns for any plant developer are uncertain— particularly in ERCOT’s energy-only market, which pays power providers only for the electricity they deliver. In other regions, capacity markets, in which power providers are compensated for holding capacity in reserve, could help ensure cost recovery for nuclear plants and likely accelerate their development.

For the past two decades, Texas consumers have largely benefitted from cheaper electricity with the increased presence of cheaper renewables. However, consumers are no longer seeing benefits to the same extent as concerns about reliability quickly escalate. Amid volatile wholesale pricing, market signals and incentives to deploy more baseload resources within ERCOT are inadequate. An adjustment to the market or incentive structure could bring more nuclear capacity into the grid, but it’s likely to push electricity bills higher.

Ultimately, Texas and the U.S. will need a diverse set of fuel sources while grappling to balance sustainability, cost and reliability. Nuclear, already part of the mix, may end up playing a larger role in the future through new technology. Commercial small modular reactors and advanced reactor designs are relatively new concepts. It remains to be seen if new reactor technology can deliver on the promise of a scalable option.

About the authors

Garrett Golding is a senior business economist in the Research Department of the Federal Reserve Bank of Dallas.

Emily Ryder Perlmeter is a senior advisor in Community Development at the Federal Reserve Bank of Dallas.

Prithvi Kalkunte is an economic programmer in the Research Department at the Federal Reserve Bank of Dallas.

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Facility for Rare Isotope Beams

At michigan state university, international research team uses wavefunction matching to solve quantum many-body problems, new approach makes calculations with realistic interactions possible.

FRIB researchers are part of an international research team solving challenging computational problems in quantum physics using a new method called wavefunction matching. The new approach has applications to fields such as nuclear physics, where it is enabling theoretical calculations of atomic nuclei that were previously not possible. The details are published in Nature (“Wavefunction matching for solving quantum many-body problems”) .

Ab initio methods and their computational challenges

An ab initio method describes a complex system by starting from a description of its elementary components and their interactions. For the case of nuclear physics, the elementary components are protons and neutrons. Some key questions that ab initio calculations can help address are the binding energies and properties of atomic nuclei not yet observed and linking nuclear structure to the underlying interactions among protons and neutrons.

Yet, some ab initio methods struggle to produce reliable calculations for systems with complex interactions. One such method is quantum Monte Carlo simulations. In quantum Monte Carlo simulations, quantities are computed using random or stochastic processes. While quantum Monte Carlo simulations can be efficient and powerful, they have a significant weakness: the sign problem. The sign problem develops when positive and negative weight contributions cancel each other out. This cancellation results in inaccurate final predictions. It is often the case that quantum Monte Carlo simulations can be performed for an approximate or simplified interaction, but the corresponding simulations for realistic interactions produce severe sign problems and are therefore not possible.

Using ‘plastic surgery’ to make calculations possible

The new wavefunction-matching approach is designed to solve such computational problems. The research team—from Gaziantep Islam Science and Technology University in Turkey; University of Bonn, Ruhr University Bochum, and Forschungszentrum Jülich in Germany; Institute for Basic Science in South Korea; South China Normal University, Sun Yat-Sen University, and Graduate School of China Academy of Engineering Physics in China; Tbilisi State University in Georgia; CEA Paris-Saclay and Université Paris-Saclay in France; and Mississippi State University and the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU)—includes  Dean Lee , professor of physics at FRIB and in MSU’s Department of Physics and Astronomy and head of the Theoretical Nuclear Science department at FRIB, and  Yuan-Zhuo Ma , postdoctoral research associate at FRIB.

“We are often faced with the situation that we can perform calculations using a simple approximate interaction, but realistic high-fidelity interactions cause severe computational problems,” said Lee. “Wavefunction matching solves this problem by doing plastic surgery. It removes the short-distance part of the high-fidelity interaction, and replaces it with the short-distance part of an easily computable interaction.”

This transformation is done in a way that preserves all of the important properties of the original realistic interaction. Since the new wavefunctions look similar to that of the easily computable interaction, researchers can now perform calculations using the easily computable interaction and apply a standard procedure for handling small corrections called perturbation theory.  A team effort

The research team applied this new method to lattice quantum Monte Carlo simulations for light nuclei, medium-mass nuclei, neutron matter, and nuclear matter. Using precise ab initio calculations, the results closely matched real-world data on nuclear properties such as size, structure, and binding energies. Calculations that were once impossible due to the sign problem can now be performed using wavefunction matching.

“It is a fantastic project and an excellent opportunity to work with the brightest nuclear scientist s in FRIB and around the globe,” said Ma. “As a theorist , I'm also very excited about programming and conducting research on the world's most powerful exascale supercomputers, such as Frontier , which allows us to implement wavefunction matching to explore the mysteries of nuclear physics.”

While the research team focused solely on quantum Monte Carlo simulations, wavefunction matching should be useful for many different ab initio approaches, including both classical and  quantum computing calculations. The researchers at FRIB worked with collaborators at institutions in China, France, Germany, South Korea, Turkey, and United States.

“The work is the culmination of effort over many years to handle the computational problems associated with realistic high-fidelity nuclear interactions,” said Lee. “It is very satisfying to see that the computational problems are cleanly resolved with this new approach. We are grateful to all of the collaboration members who contributed to this project, in particular, the lead author, Serdar Elhatisari.”

This material is based upon work supported by the U.S. Department of Energy, the U.S. National Science Foundation, the German Research Foundation, the National Natural Science Foundation of China, the Chinese Academy of Sciences President’s International Fellowship Initiative, Volkswagen Stiftung, the European Research Council, the Scientific and Technological Research Council of Turkey, the National Natural Science Foundation of China, the National Security Academic Fund, the Rare Isotope Science Project of the Institute for Basic Science, the National Research Foundation of Korea, the Institute for Basic Science, and the Espace de Structure et de réactions Nucléaires Théorique.

Michigan State University operates the Facility for Rare Isotope Beams (FRIB) as a user facility for the U.S. Department of Energy Office of Science (DOE-SC), supporting the mission of the DOE-SC Office of Nuclear Physics. Hosting what is designed to be the most powerful heavy-ion accelerator, FRIB enables scientists to make discoveries about the properties of rare isotopes in order to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions, and applications for society, including in medicine, homeland security, and industry.

The U.S. Department of Energy Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of today’s most pressing challenges. For more information, visit energy.gov/science.