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Decades of failure to cut fossil fuels<ref>See [https://ourworldindata.org/grapher/global-primary-energy?country=~OWID_WRL ourworldindata.org/grapher/global-primary-energy] for the record on world energy.</ref> has led to a '''reconsideration of [[Nuclear power|nuclear power]]''' as a source of carbon-free energy. Among the alternatives to [[Fossil_fuel|fossil fuels]], nuclear is unique in that it can provide reliable, dispatchable<ref>"Load following" is the term used by utilities, and is especially important when there is a lot of wind and solar on the grid.  Some reactors are not able to do this.</ref> power regardless of the weather and can be deployed anywhere in the world. Meeting the world's needs for reliable carbon-free energy will require thousands of nuclear plants or perhaps a breakthrough in technology to store energy from wind and solar.
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<ref>[https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity Pumped storage] is currently the most economical way to store electric power, but it requires a large reservoir on a nearby hill, or in an abandoned mine. [https://www.energy.gov/sites/default/files/2019/07/f65/Storage%20Cost%20and%20Performance%20Characterization%20Report_Final.pdf Li-ion battery systems] at $500 per KWh are not practical for utility-scale storage. See
<onlyinclude>
[https://world-nuclear.org/information-library/current-and-future-generation/electricity-and-energy-storage.aspx Energy Storage] for a good summary of other alternatives.</ref>  
After decades of failure to slow the rising global consumption of [[Fossil_fuel|coal, oil and gas]],<ref name=GlobalEnergyGrowth>[https://ourworldindata.org/grapher/global-primary-energy?country=~OWID_WRL Global Energy Growth] by Our World In Data</ref> many countries have concluded that the world needs to '''reconsider nuclear power''' in order to lower the demand for fossil fuels.<ref name=PublicFigures>Public figures who have reconsidered their stance on nuclear power are listed on the [[Nuclear power reconsidered/External_Links|External Links]] tab of this article.</ref> Wind and solar power alone, without large-scale [[Energy_storage|storage]] for these intermittent sources, are unlikely to meet the world's needs for reliable energy.<ref name=StoringPower1>[https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity Pumped storage] is currently the most economical way to store electricity, but it requires a large reservoir on a nearby hill or in an abandoned mine. [https://www.energy.gov/sites/default/files/2019/07/f65/Storage%20Cost%20and%20Performance%20Characterization%20Report_Final.pdf Li-ion battery systems] at $500 per KWh are not practical for utility-scale storage. See [https://world-nuclear.org/information-library/current-and-future-generation/electricity-and-energy-storage.aspx Energy Storage] for a summary of other alternatives.</ref><ref name=StoringPower2>Utilities that include wind and solar power in their grid must have non-intermittent generating capacity (typically fossil fuels) to handle maximum demand for several days. They can save on fuel, but the cost of the plant is the same with or without intermittent sources.</ref><ref name=StoringPower3>Mark Jacobson believes that long-distance transmission lines can provide an alternative to costly storage. See the bibliography for more on this proposal and the critique by Christopher Clack.</ref> See Figures 1 and 2 on the magnitude of the world energy challenge.
<ref>Utilities that include wind and solar power in their grid must have non-intermittent generating capacity (typically fossil fuels) to handle maximum demand for several days. They can save on fuel, but the cost of the plant is the same, with or without the intermittent sources.</ref>
<ref>Mark Jacobson believes that long-distance transmission lines can provide an alternative to costly storage. See the bibliography for more on this proposal and the critique by Christopher Clack.</ref>
(See Figs. 1 and 2 on the magnitude of the world energy challenge.)
{{Image|World Electric Power.png|right|350px|Fig.1 Electricity consumption may soon double, mostly from coal-fired power plants in the developing world.<ref>[https://gordianknotbook.com Fig.1.3 in Devanney "Why Nuclear Power has been a Flop"]</ref>}}
{{Image|Energy US 2020.png|right|350px|Fig.2 Electricity is only one third of the CO2 problem. Other big needs include low-cost high-temperature process heat for industry <ref>Heat from electricity is very inefficient. Using nuclear heat directly from a reactor is possible for many industrial processes.</ref> and fuels for the transportation sector.<ref>Generation of hydrogen for fuel is possible with a [https://www.gen-4.org/gif/jcms/c_9362/vhtr Very High Temperature Reactor].</ref>}}


The purpose of this article is to examine the issues that have held back widespread use of nuclear power. These issues include safety, waste management, weapons proliferation, and cost. Many new reactor designs have been proposed that seek to address these issues. We will try to establish objective criteria to evaluate these new designs and to facilitate public discussion on the question of what role should nuclear power play in the coming worldwide move away from fossil fuels.
[[Nuclear power plant]]s that use [[nuclear reactor]]s to create electricity could provide the abundant, zero-carbon, dispatchable<ref name=LoadFollowing>"Load following" is the term used by utilities, and is important when there is a lot of wind and solar on the grid. Some reactors are not able to do this.</ref> energy needed for a low-carbon future, but not by simply building more of what we already have. New innovative designs for nuclear reactors are needed to avoid the problems of the past.


To regain public confidence in nuclear power, reviews of these new designs should be transparent, with all arguments, for and against, published for public comment. It is essential that we include people who have engineering experience, but are not connected to the nuclear industry or any political advocacy group.
{{Image|World Electric Power.png|right|300px|Fig.1 Electricity consumption may soon double, mostly from coal-fired power plants in the developing world.<ref name=GordianKnotFig1.3>[https://gordianknotbook.com Fig.1.3 in Devanney "Why Nuclear Power has been a Flop"]</ref>}}
</onlyinclude>
{{Image|Energy US 2020.png|right|350px|Fig.2 Electricity is only a third of the CO<sub>2</sub> problem. Other big needs include low-cost high-temperature process heat for industry<ref name=Fig2imageA>Heat from electricity is very inefficient. Using nuclear heat directly from a reactor is possible for many industrial processes.</ref> and fuels for the transportation sector.<ref name=Fig2imageB>Generation of hydrogen for fuel is possible with a [https://www.gen-4.org/gif/jcms/c_9362/vhtr Very High Temperature Reactor].</ref>}}
<onlyinclude>


== Issues Confronting the Nuclear Industry ==
== Issues Confronting the Nuclear Industry ==
New reactor designers have sought to address issues that have prevented the acceptance of nuclear power, including safety, waste management, weapons proliferation, and cost. This article will summarize the questions that have been raised and the criteria that have been established for evaluating these designs. Answers to these questions will be provided by the designers of these reactors in the articles on their designs. Further debate will be provided in the Discussion and the Debate Guide pages of those articles.
</onlyinclude>
=== Safety ===
=== Safety ===
{{Image|What-is-the-safest-form-of-energy.png|right|350px|Fig.3 Historical record on safety and CO2 emissions.<ref> [https://ourworldindata.org/safest-sources-of-energy Our World in Data - What are the safest and cleanest sources of energy?]</ref>}}
{{Image|What-is-the-safest-form-of-energy.png|right|350px|Fig.3 Historical record on safety and CO2 emissions.<ref name=Fig3image1 />}}
Widespread deployment of [[Nuclear reactor|nuclear reactors]] will require the new designs to address not only the problems that have lead to accidents in the past, but also what might be conceivable in the future, including natural disasters and sabotage. Nuclear power over the last 50 years, when measured by objective criteria like number of deaths per terawatt hour of energy produced, has been safer than even natural gas (the safest of the fossil fuels), and comparable to wind and solar (Fig.3). The new designs will be even safer.  
Nuclear accidents have been compared to airplane crashes - in the public mind, far more horrible than the numbers actually warrant. Figure 3 shows how many deaths worldwide are resulting from the use of fossil fuels and other energy sources. Nuclear power over the last 50 years, when measured by objective criteria like number of deaths per terawatt hour of energy produced, has been safer than even natural gas (the safest of the fossil fuels), and comparable to wind and solar. In spite of this record on safety, the fears remain.<ref name=fear/> Widespread deployment of nuclear reactors will require that the new designs address not only the fears that have arisen from accidents in the past, but also what might be conceivable in the future, including natural disasters, sabotage, and cyber attacks.<ref name=security />


Nuclear accidents are like airplane crashes - in the public mind far more horrible than coal mine disasters or everyday car crashes. The public cannot tolerate another Three Mile Island. A new design must be "walk away safe" - that is, the ability to shut itself down even if the operators just walk away and do nothing to prevent an accident. Let's call this level of safety S-1. Beyond that, we could require S-2 - no way the operators (or terrorists) can cause a radiation leak by overriding the normal controls. Finally, let's call S-3 the highest level of safety - no way, even using explosives, that terrorists could cause a leak. S-3 may be impossible to achieve. In that case, we must consider possible scenarios and our response.
Because even a harmless malfunction can influence public opinion and set back deployment of nuclear power for decades, some proponents of the new designs are calling them "walk away safe" - that is, they are designed with the ability to shut down safely even if the operators just walk away and do nothing to prevent an accident.<ref name=safetyTest/>  Let us call this level of safety S-1.


Scenario Sab-1: Terrorists arrive with cable cutters, a hacksaw, and a memory stick with some malware from North Korea.<ref>Cybersecurity is an increasing risk for control systems connected to the Internet. See [https://world-nuclear.org/information-library/safety-and-security/security/security-of-nuclear-facilities-and-material.aspx The threats from cyberspace]</ref> The operators are expelled, except one, whose daughter is held hostage, and will be killed if anything goes wrong with the terrorist plan.
Beyond that, regulators could require safety level S-2 - that is, no way the operators (or terrorists) can cause a radiation leak by overriding the normal controls.  


Scenario Sab-2: The terrorists have heavy equipment to drill through concrete, and a pump truck with some kind of explosive liquid.
Finally, regulators could require safety level S-3, the highest level of safety - that is, no way, even using explosives, that terrorists could cause a disaster. S-3 may be impossible to achieve. In that case, reactor designers must consider possible scenarios and what the response would need to be.<ref name=AlScott/>


Scenario Sab-3: The terrorists have hired El Chapo's tunneling team to come at the reactor from underground.
Scenario Sab-1: Terrorists arrive with cable cutters, a hacksaw, and a memory stick with some malware from North Korea. The operators are expelled, except one, whose daughter is held hostage, and will be killed if anything goes wrong with the terrorist plan.
 
Scenario Sab-2: The terrorists have heavy equipment to drill through concrete, and a pump truck with some brown liquid.
 
Scenario Sab-3: The terrorists have hired El Chapo's tunneling team to come at the reactor from underground.<ref name=tunnel/>


There may be dozens of scenarios to consider, including tsunamis, hijacked airplanes, and even a meteorite strike. The public should be encouraged, perhaps even rewarded for submitting scenarios worthy of consideration. The Fukushima disaster could have been avoided, if someone had thought to keep pump trucks on a nearby hill.
There may be dozens of scenarios to consider, including tsunamis, hijacked airplanes, and even a meteorite strike. The public should be encouraged, perhaps even rewarded for submitting scenarios worthy of consideration. The Fukushima disaster could have been avoided, if someone had thought to keep pump trucks on a nearby hill.
''See also  [[Radiation_Hazards]] and [[Fear of radiation]].''


=== Waste Management ===
=== Waste Management ===
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uranium.<ref>https://blogs.egu.eu/network/geosphere/2015/02/02/geopoll-what-should-we-do-with-radioactive-waste/</ref>}}
uranium.<ref>https://blogs.egu.eu/network/geosphere/2015/02/02/geopoll-what-should-we-do-with-radioactive-waste/</ref>}}


How much waste is produced compared to other sources of energy? How will it be contained, and what are the dangers to people and the environment? Like questions on safety, public perception of the dangers of nuclear waste is much worse than historical data shows.<ref>“Over the last 40 years, thousands of shipments of commercially generated spent nuclear fuel have been made throughout the United States without causing any radiological releases to the environment or harm to the public.” - statement by the Nuclear Regulatory Commission quoted in [https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-waste/storage-and-disposal-of-radioactive-waste.aspx Storage and Disposal of Radioactive Waste]</ref>  The volume of waste per per terawatt-hour is 100,000 times less than coal.<ref>section 2.2 "A Beautifully Small Problem" in the book [https://gordianknotbook.com Why Nuclear Power has been a Flop].</ref> Even if we look only at radioactivity released to the environment,<ref>[https://www.epa.gov/radtown/radioactive-wastes-coal-fired-power-plants Radioactive Wastes From Coal-fired Power Plants] US Environmental Protection Agency</ref> watt-for-watt nuclear power is 100 times less than coal.<ref>https://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/ - The title is a bit misleading. From the article: "In fact, the fly ash emitted by a power plant—a by-product from burning coal for electricity—carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy." "ounce for ounce, coal ash released from a power plant delivers more radiation than nuclear waste shielded via water or dry cask storage."</ref>
How much waste is produced compared to other sources of energy? How will it be contained, and what are the dangers to people and the environment? Like questions on safety, public perception of the dangers of nuclear waste is much worse than historical data shows.<ref>“Over the last 40 years, thousands of shipments of commercially generated spent nuclear fuel have been made throughout the United States without causing any radiological releases to the environment or harm to the public.” - statement by the Nuclear Regulatory Commission quoted in [https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-waste/storage-and-disposal-of-radioactive-waste.aspx Storage and Disposal of Radioactive Waste]</ref>  The volume of waste per terawatt-hour is 100,000 times less than coal.<ref>section 2.2 "A Beautifully Small Problem" in the book [https://gordianknotbook.com Why Nuclear Power has been a Flop].</ref> Even if only looking at radioactivity released to the environment,<ref>[https://www.epa.gov/radtown/radioactive-wastes-coal-fired-power-plants Radioactive Wastes From Coal-fired Power Plants] US Environmental Protection Agency</ref> watt-for-watt nuclear power is 100 times less than coal.<ref>https://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/ - The title is a bit misleading. From the article: "In fact, the fly ash emitted by a power plant—a by-product from burning coal for electricity—carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy." "ounce for ounce, coal ash released from a power plant delivers more radiation than nuclear waste shielded via water or dry cask storage."</ref>


Much of the worry about nuclear waste centers around the long life of some isotopes in the waste (See Fig.4). There is concern about leakage into the environment decades or even centuries from now.
Much of the worry about nuclear waste centers around the long life of some low-level <ref name=lowlevel/> isotopes in the waste (See Fig.4). There is concern about leakage into the environment decades or even centuries from now.
Billion-dollar efforts to bury the waste deep under a mountain have only heightened public fears. Dry-cask storage at the power plants has proven to be a safe but temporary solution.<ref>Connecticut Yankee, a 619 MWe reactor on the Connecticut River, ran for 28 years between 1968 and 1996. The spent fuel from those 28 years is stored in 43 casks on a concrete pad, 70 feet by 228 feet.</ref>  
Billion-dollar efforts to bury the waste deep under a mountain have only heightened public fears. Dry-cask storage at the power plants has proven to be a safe but temporary solution.<ref name=Yankee/>  
This interim storage has the advantage of being able to recover the "waste" and use it in newer reactors that can use the remaining 95% of available energy.
This interim storage has the advantage of being able to recover the "waste" and burn it in newer reactors that can use the remaining 97% of available energy.<ref name=97pct/>


Transportation of wastes from reactors to disposal or reprocessing sites must be done safely. Leakage into groundwater and ocean water near shore is a special concern. New reactor designs must address these concerns, even though they go beyond the design of the reactor itself. Will the waste be solid or liquid? Will it require special casks, or even special vehicles for transportation on public roads? (See Fig.5)
Transportation of spent fuel from reactors to disposal or reprocessing sites must be done safely. Reprocessing should be done at secure locations to avoid diversion of dangerous materials.<ref>See [https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/fuel-recycling/processing-of-used-nuclear-fuel.aspx Processing of Used Nuclear Fuel] for discussion of various reprocessing methods and their ability to separate fissile materials from the waste.</ref> Leakage into groundwater and ocean water near shore is a special concern. New reactor designs must address these concerns, even though they go beyond the design of the reactor itself. Will the waste be solid or liquid? Will it require special casks, or even special vehicles for transportation on public roads? (See Fig.5)
{{Image|Transport of Used Nuclear Fuel in Japan.jpg|right|350px|Fig.5 Transport of Nuclear Fuel in Japan.<ref>[https://world-nuclear.org/information-library/nuclear-fuel-cycle/transport-of-nuclear-materials/transport-of-radioactive-materials.aspx Transport of Radioactive Materials] World Nuclear Association</ref>}}
{{Image|Transport of Used Nuclear Fuel in Japan.jpg|right|350px|Fig.5 Transport of Nuclear Fuel in Japan.<ref>[https://world-nuclear.org/information-library/nuclear-fuel-cycle/transport-of-nuclear-materials/transport-of-radioactive-materials.aspx Transport of Radioactive Materials] World Nuclear Association</ref>}}


Other worries include the possibility of sabotage or theft of waste material that might be useful in a "dirty bomb". Again, we should evaluate specific plans by considering likely scenarios. Is the storage facility away from any population center and not a target for an airplane crash, a truck bomb, or even a short-range missile? Is there a secure perimeter with intrusion detectors? If there is an intrusion, is cutting through the concrete and steel difficult enough that there will be plenty of time for a response from local law enforcement, or even a nearby military base? (See Fig.6)
Other worries include the possibility of sabotage or theft of waste material that might be useful in a "dirty bomb". Again, regulators should evaluate specific plans by considering likely scenarios. Is the storage facility away from any population center and not a target for an airplane crash, a truck bomb, or even a short-range missile? Is there a secure perimeter with intrusion detectors? If there is an intrusion, is cutting through the concrete and steel difficult enough that there will be plenty of time for a response from local law enforcement, or even a nearby military base? (See Fig.6)
{{Image|Nuclear Fuel Storage.png|right|350px|Fig.6 Dry underground storage in the desert, safe but still recoverable.}}
{{Image|Nuclear Fuel Storage.png|right|350px|Fig.6 Dry underground storage in the desert, safe but still recoverable.}}


It is important that we make a distinction between waste from nuclear power, and the waste from bomb production, which was often done in a rush with little concern for pollution. Spent fuel rods can be stored safely. Weapons waste poses a much bigger problem due to the large variety and sometimes unexpected characteristics of the material to be stored.<ref>A barrel containing plutonium mixed with kitty litter exploded days after it was "safely" stored at the Waste Isolation Pilot Plant, leading to "Nuclear accident in New Mexico ranks among the costliest in U.S. history" [https://www.latimes.com/nation/la-na-new-mexico-nuclear-dump-20160819-snap-story.html LA Times]</ref> In evaluating a new reactor design, we must look at the complete fuel cycle, not just the waste from the reactor itself. Are there any problems with the mining, processing, or transportation of the fuel, or with the reprocessing of spent fuel?
It is important to make a distinction between spent fuel from nuclear power, and the waste from bomb production, which was often done in a rush with little concern for pollution. Spent fuel rods can be stored safely. Weapons waste poses a much bigger problem due to the large variety and sometimes unexpected characteristics of the material to be buried.<ref name=WIPPleak/> In evaluating a new reactor design, regulators must look at the complete fuel cycle, not just the waste from the reactor itself. Are there any problems with the mining, processing, or transportation of the fuel, or with the reprocessing of spent fuel?
 
''See also [[Nuclear_waste_management]]''.


=== Weapons Proliferation ===
=== Weapons Proliferation ===
Will deployment of reactors to untrusted countries, or countries that might be taken over by rogue actors, increase the risk of proliferation, either by theft of materials in the reactor, or by modification of the reactor to produce weapons-grade materials? Will fuel processing or other activities connected with nuclear power provide cover for a weapons program? Will knowledge of the new reactor designs lead to easier ways to make bombs?  
Will deployment of reactors to untrusted countries, or countries that might be taken over by rogue actors, increase the risk of proliferation, either by theft of materials in the reactor, or by modification of the reactor to produce weapons-grade materials? Will fuel processing or other activities connected with nuclear power provide cover for a weapons program or a basis for a quick sprint to bomb making? Will knowledge of the new reactor designs or process technologies lead to easier ways to make bombs?


There are three nuclides with potential for making a bomb: U-233, U-235, and Pu-239. Every reactor design has a characteristic isotopic composition in its fuel, which evolves over time as the fuel is consumed. Some uranium reactors have a brief period in their fuel cycle where weapons-grade Pu-239 can be extracted from the partially used fuel. Some thorium reactors with on-site fuel processing may be vulnerable to skimming of a small fraction of U-233 from the process loop.<ref>Thorium fuel has risks, Ashley 2012, https://www.nature.com/articles/492031a</ref> Some molten salt reactors start with uranium enriched to 20% U-235, and that might provide a head-start to a country wanting to enrich all the way to bomb-grade.
There are three nuclides with potential for making a bomb: U-233, U-235, and Pu-239. Every reactor design has a characteristic isotopic composition in its fuel, which evolves over time as the fuel is consumed. Some uranium reactors have a brief period in their fuel cycle where weapons-grade Pu-239 can be extracted from the partially used fuel. Some thorium reactors with on-site fuel processing may be vulnerable to skimming of a small fraction of U-233 from the process loop.<ref>Thorium fuel has risks, Ashley 2012, https://www.nature.com/articles/492031a</ref> Some molten salt reactors start with uranium enriched to 20% U-235, and that might provide a head-start to a country wanting to enrich all the way to bomb-grade.


Considerations like these favor designs in which all fuel processing is done at secure locations, and there is never any weapons grade material easily extracted from an operating reactor. The requirement should not be perfection, but simply that a new reactor should not allow an easier route to bomb making than currently available centrifuges.
Considerations like these favor designs in which all fuel processing is done at secure locations, and there is never any weapons grade material easily extracted from an operating reactor. The requirement should not be perfection, but simply that a new reactor should not allow an easier route to bomb making than currently available centrifuges.
''See also [[Nuclear_proliferation]]''


=== Cost ===
=== Cost ===
How will the cost compare to existing power sources including wind and solar? Existing nuclear plants have been very expensive, due to the inherent risks in pressurized water reactors (PWR's) and the need for expensive structures and burdensome regulations to deal with that risk. Newer designs promise to be much simpler, safer, and manufactured on an assembly line as replaceable parts,<ref>Elimination of "decommissioning" costs will greatly improve the long-term economy of nuclear plants [https://www.youtube.com/watch?v=eoU3U7TYNLA Can Nuclear Plants be Immortal, Mark Nelson]</ref> rather than site built. Elimination of water at high pressure and temperature avoids the risk of steam explosions. Cost is a lesser worry than the other issues, because the risk can be born by private companies promising to deliver reactors at an agreed price.
How will the cost compare to existing power sources including wind and solar? Existing nuclear plants have been very expensive, due to the inherent risks in Pressurized Water Reactors (PWR's) and the need for expensive structures and burdensome regulations to deal with that risk. Newer designs promise to be simpler, safer, and manufactured on an assembly line as replaceable parts, rather than site built. Elimination of water at high pressure and temperature avoids the risk of steam explosions. Reactor vessels with non-destructive "meltdown" behavior avoid the risk of another Fukushima.<ref>A liquid fuel reactor can have plugs at the bottom of the reactor vessel that melt if the reactor gets too hot. The fuel then flows safely into drain tanks.</ref>
 
Plants with replaceable parts can operate indefinitely,<ref>Elimination of "decommissioning" costs will greatly improve the long-term economy of nuclear plants [https://www.youtube.com/watch?v=eoU3U7TYNLA Can Nuclear Plants be Immortal, Mark Nelson]</ref> but if a plant is decommissioned, the process is little more than pulling out but not replacing all the parts. Cost is a lesser worry than the other issues, because the risk can be born by private companies promising to deliver reactors at an agreed price.<ref>ThorCon has presented a [https://thorconpower.com/economics detailed analysis] showing the cost of their proposed plants as less than a coal plant.</ref> See [[Cost_of_nuclear_power]] for further discussion.


One remaining worry is future costs if fuel or some essential material becomes scarce. Some PWR's require hafnium in their control rods, and there was worry about the world supply of hafnium if thousands of these reactors were to be deployed in the coming decades.<ref>D. Abbott, "Is Nuclear Power Globally Scalable?" Proceedings of the IEEE, vol. 99, no. 10, pp. 1611-1617, Oct. 2011, https://ieeexplore.ieee.org/document/6021978. See section XIII on the hafnium problem.</ref>
One remaining worry is future costs if fuel or some essential material becomes scarce. Some PWR's require hafnium in their control rods, and there was worry about the world supply of hafnium if thousands of these reactors were to be deployed in the coming decades.<ref>D. Abbott, "Is Nuclear Power Globally Scalable?" Proceedings of the IEEE, vol. 99, no. 10, pp. 1611-1617, Oct. 2011, https://ieeexplore.ieee.org/document/6021978. See section XIII on the hafnium problem.</ref>
As for the cost of fuel, the World Nuclear Association says it is essentially unlimited.<ref>[https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/uranium-resources/supply-of-uranium.aspx Supply of Uranium] World Nuclear Association</ref> Some of the new reactors can burn<ref>The fissioning of nuclear fuel, sometimes called "burning" should not be confused with ordinary chemical reactions like oxidation that occurs when fossil fuels are burned.</ref> all the uranium, not just the 0.7% now burned by PWRs, and they can even burn thorium, which is three times more abundant than uranium.
As for the supply of fuel, the World Nuclear Association says it is essentially unlimited.<ref>[https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/uranium-resources/supply-of-uranium.aspx Supply of Uranium] World Nuclear Association. See also [https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6021978 Abbott 2011] for a counter-argument to the WNA assessment.</ref> Some of the new reactors can burn<ref>The fissioning of nuclear fuel, sometimes called "burning" should not be confused with ordinary chemical reactions like oxidation that occurs when fossil fuels are burned.</ref> all the uranium, not just the 0.7% now burned by PWRs, and they can even burn thorium, which is three times more abundant than uranium.


== Proposed Designs ==
''See also [[Cost_of_nuclear_power]].''
Here is a brief summary of several promising designs. Click on the heading for a response to the issues raised in this article.
=== [[ThorCon nuclear reactor|MSR]] ===
This is a [[Molten salt reactor|Molten Salt Reactor]] based on proven technology, intended for a short-term solution (decades) while more advanced designs are perfected.<ref>https://thorconpower.com/docs/docs_v130_isle20190315.pdf</ref>


=== [[FC-MSR nuclear reactor|FNR]] ===
== New Reactor Designs ==
This is a Fast Neutron Reactor capable of burning spent nuclear fuel, old bomb cores, depleted uranium, and  
Here is a brief summary of several reactor types and representative examples of each type. See the specific reactor designs for responses to the issues raised in this article.
thorium.<ref>Ed Pheil, Chief Technology Officer at Elysium Industries, speaks at Thorium Energy Alliance 2020, https://www.youtube.com/watch?v=_ou_xswB2b0</ref>


=== [[High Temperature Gas-cooled Reactor|HTGR]] ===
=== Small Modular Reactors ===
The High Temperature Gas-cooled Reactor uses helium gas as a coolant and can provide process heat for production of zero-carbon hydrogen from water.<ref>[[High Temperature Gas-cooled Reactor]]</ref>
Small Modular Reactors (SMRs) include any type of reactor that is smaller than a conventional reactor, can be built as modules on an assembly line, delivered to the site where power is needed, and returned for recycling or disposal. The first SMR to be licensed in the United States <ref name=NuScaleLic/> was the
[[NuScale small modular reactor|NuScale SMR]], a smaller version of a standard [[Pressurized Water Reactor]] (PWR) with additional safety features.<ref name=NuScale/> NuScale has unfortunately failed to meet its promise of low cost.<ref name=Debacle/>


=== [[NuScale small modular reactor|PWR]] ===
=== Molten Salt Reactors ===
This is a smaller version of a standard Pressurized Water Reactor with all the latest safety features.
[[Molten salt reactor|Molten Salt Reactors]] (MSRs) provide higher temperature and better thermal efficiency than PWRs, while avoiding the risk of meltdown and high-pressure steam explosions inherent in PWRs.
<ref>https://www.science.org/news/2019/02/smaller-safer-cheaper-one-company-aims-reinvent-nuclear-reactor-and-save-warming-planet</ref>
The [[ThorCon nuclear reactor]] is an MSR based on proven technology, intended for a short-term solution (decades) while more advanced designs are perfected.<ref>https://thorconpower.com/docs/docs_v130_isle20190315.pdf</ref>
 
=== Fast Neutron Reactors ===
[[Fast neutron reactor|Fast Neutron Reactors]] (FNRs) are capable of burning spent nuclear fuel, old bomb cores, depleted uranium, and
thorium. FNRs can breed more fissile material than they consume,<ref name=plentiful/> making them the current best bet for long-term energy sustainability.<ref name=bet/> This technology is not speculative, as are fusion <ref name=fusion/> and new breakthroughs in [[Energy storage|storage]]. The [[Integral Fast Reactor]] is a metal-fueled, sodium-cooled, pool-type FNR.
 
{{Image|SMR_temperature.png|right|350px|Fig.7 Zero-carbon, very high-temperature process heat will be needed for some industries.}}
=== High Temperature Gas-cooled Reactors ===
[[High Temperature Gas-cooled Reactor|High Temperature Gas-cooled Reactors]] (HTGRs) use inert helium gas as a coolant and can provide temperatures even higher than MSRs. These reactors may prove useful for industries needing zero-carbon, high-temperature process heat, like the production of hydrogen from water and the refining of steel. See Figure 7.


=Further Reading=
=Further Reading=
[https://electrifyingourworld.com Electrifying Our World] Robert Hargraves excellent overview of energy, the growth human civilization, and possible solutions to the current climate crisis.<br>
* [https://electrifyingourworld.com Electrifying Our World] Dr.Robert Hargraves' excellent overview of energy, the growth human civilization, and possible solutions to the problems of energy poverty and global warming.<br>
[https://world-nuclear.org/information-library.aspx World Nuclear Information Library] a well-organized authoritative collection of information on nuclear power.<br/>
* [https://whatisnuclear.com What is Nuclear Energy] Dr. Nick Touran's easy introduction to nuclear energy by a group of nuclear engineers.<br>
[https://ourworldindata.org Our World in Data] has a section on Energy and Environment with nice interactive graphics.<br/>
* [https://world-nuclear.org/information-library.aspx World Nuclear Information Library] a comprehensive, authoritative collection of information on nuclear energy.<br/>
* [https://ourworldindata.org Our World in Data] has a section on Energy and Environment with nice interactive graphics.<br/>
* [https://jackdevanney.substack.com/p/site-directory Gordian Knot News] a collection of well-researched articles by Jack Devanney, an engineer with long experience in the nuclear industry.


=Notes and References=
=Notes and References=
{{Reflist|2}}
{{Reflist|refs=
 
<ref name=97pct>If we include in recoverable energy the depleted uranium produced in the enrichment process, we are using only 0.5% of the available energy. Fast Neutron Reactors with reprocessing could be 200 times more efficient in use of our mined uranium resources.
</ref>
<ref name=AlScott>
Requiring this level of safety may be unreasonable. See Al Scott's argument against "disaster porn" on the [[Nuclear_power_reconsidered/Debate_Guide#Sabotage_scenarios_are_disaster_porn|Debate Guide]] page.
</ref>
<ref name=bet>
The leading alternative (wind and solar) will require a breakthrough in [[Energy storage|storage technology]].
</ref>
<ref name=Debacle>
See Jack Devanney's [https://jackdevanney.substack.com/p/the-nuscale-debacle article] on the failure of NuScale.
</ref>
<ref name=fear>
See [[Fear_of_radiation]] for discussion of these fears and the evidence contradicting widely-held beliefs about the dangers of nuclear power.
</ref>
<ref name=Fig3image1> 
[https://ourworldindata.org/safest-sources-of-energy Our World in Data - What are the safest and cleanest sources of energy?]
</ref>
<ref name=fusion>
The most recent "breakthrough" in fusion, a "breakeven" demonstration (fusion energy out = laser energy in) is still a factor of 100 short of breakeven on electrical energy in vs electrical energy out. Nobody has even a conceptual design for a laser fusion plant costing less than a trillion dollars.
</ref>
<ref name=lowlevel>Long-lived isotopes in spent nuclear fuel have both lower intensity and lower penetrating power than the short-lived fission products that are gone in 600 years. See the [[Nuclear_waste_management/Debate_Guide#Nuclear_Waste_Lasts_Forever|Nuclear Waste Lasts Forever]] section of the Debate Guide page of our Nuclear Waste Management article.
</ref>
<ref name=NuScale>https://www.science.org/news/2019/02/smaller-safer-cheaper-one-company-aims-reinvent-nuclear-reactor-and-save-warming-planet
</ref>
<ref name=NuScaleLic>[https://newatlas.com/energy/nrc-certifies-nuscale-nuclear US nuclear regulator greenlights its first small modular reactor] August 2022.
</ref>
<ref name=plentiful>
Breeding (the conversion of "fertile" to "fissile" isotopes) can multiply the amount of usable fuel by a factor of a hundred. See section 5.2 The Fuel Choice in ''Plentiful Energy'', Till & Chang 2011
[http://www.thesciencecouncil.com/pdfs/PlentifulEnergy.pdf ISBN: 978-1466384606].
</ref>
<ref name=safetyTest>A common test for "walkaway safe" is to shut off all safety systems, including emergency cooling, jam the rods full throttle, and see what happens.[https://citizendium.org/wiki/Integral_Fast_Reactor#Safety Integral Fast Reactor Safety Test]
</ref>
<ref name=security>
Cybersecurity is an increasing risk for control systems connected to the Internet. See the WNA assessment of the [https://world-nuclear.org/information-library/safety-and-security/security/security-of-nuclear-facilities-and-material.aspx threat from cyberspace].
</ref>
<ref name=tunnel>
[https://www.cnn.com/2015/07/12/americas/mexico-el-chapo-escape-sinaloa-cartel-tunnels/index.html El Chapo's escape]
</ref>
<ref name=WIPPleak>
A barrel containing plutonium mixed with kitty litter ruptured after it was stored at the Waste Isolation Pilot Plant, leading to "Nuclear accident in New Mexico ranks among the costliest in U.S. history" [https://www.latimes.com/nation/la-na-new-mexico-nuclear-dump-20160819-snap-story.html LA Times]
</ref>
<ref name=Yankee>Connecticut Yankee, a 619 MWe reactor on the Connecticut River, ran for 28 years between 1968 and 1996. The spent fuel from those 28 years is stored in 43 casks on a concrete pad, 70 feet by 228 feet.
</ref>
 
}}
 
{{Authors|David MacQuigg}}

Latest revision as of 13:36, 19 March 2024

This article is developed but not approved.
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This editable, developed Main Article is subject to a disclaimer.

After decades of failure to slow the rising global consumption of coal, oil and gas,[1] many countries have concluded that the world needs to reconsider nuclear power in order to lower the demand for fossil fuels.[2] Wind and solar power alone, without large-scale storage for these intermittent sources, are unlikely to meet the world's needs for reliable energy.[3][4][5] See Figures 1 and 2 on the magnitude of the world energy challenge.

Nuclear power plants that use nuclear reactors to create electricity could provide the abundant, zero-carbon, dispatchable[6] energy needed for a low-carbon future, but not by simply building more of what we already have. New innovative designs for nuclear reactors are needed to avoid the problems of the past.

(CC) Image: Geoff Russell
Fig.1 Electricity consumption may soon double, mostly from coal-fired power plants in the developing world.[7]
© Image: Lawrence Livermore Lab
Fig.2 Electricity is only a third of the CO2 problem. Other big needs include low-cost high-temperature process heat for industry[8] and fuels for the transportation sector.[9]


Issues Confronting the Nuclear Industry

New reactor designers have sought to address issues that have prevented the acceptance of nuclear power, including safety, waste management, weapons proliferation, and cost. This article will summarize the questions that have been raised and the criteria that have been established for evaluating these designs. Answers to these questions will be provided by the designers of these reactors in the articles on their designs. Further debate will be provided in the Discussion and the Debate Guide pages of those articles.

Safety

Fig.3 Historical record on safety and CO2 emissions.[10]

Nuclear accidents have been compared to airplane crashes - in the public mind, far more horrible than the numbers actually warrant. Figure 3 shows how many deaths worldwide are resulting from the use of fossil fuels and other energy sources. Nuclear power over the last 50 years, when measured by objective criteria like number of deaths per terawatt hour of energy produced, has been safer than even natural gas (the safest of the fossil fuels), and comparable to wind and solar. In spite of this record on safety, the fears remain.[11] Widespread deployment of nuclear reactors will require that the new designs address not only the fears that have arisen from accidents in the past, but also what might be conceivable in the future, including natural disasters, sabotage, and cyber attacks.[12]

Because even a harmless malfunction can influence public opinion and set back deployment of nuclear power for decades, some proponents of the new designs are calling them "walk away safe" - that is, they are designed with the ability to shut down safely even if the operators just walk away and do nothing to prevent an accident.[13] Let us call this level of safety S-1.

Beyond that, regulators could require safety level S-2 - that is, no way the operators (or terrorists) can cause a radiation leak by overriding the normal controls.

Finally, regulators could require safety level S-3, the highest level of safety - that is, no way, even using explosives, that terrorists could cause a disaster. S-3 may be impossible to achieve. In that case, reactor designers must consider possible scenarios and what the response would need to be.[14]

Scenario Sab-1: Terrorists arrive with cable cutters, a hacksaw, and a memory stick with some malware from North Korea. The operators are expelled, except one, whose daughter is held hostage, and will be killed if anything goes wrong with the terrorist plan.

Scenario Sab-2: The terrorists have heavy equipment to drill through concrete, and a pump truck with some brown liquid.

Scenario Sab-3: The terrorists have hired El Chapo's tunneling team to come at the reactor from underground.[15]

There may be dozens of scenarios to consider, including tsunamis, hijacked airplanes, and even a meteorite strike. The public should be encouraged, perhaps even rewarded for submitting scenarios worthy of consideration. The Fukushima disaster could have been avoided, if someone had thought to keep pump trucks on a nearby hill.

See also Radiation_Hazards and Fear of radiation.

Waste Management

Fig.4 Radioactivity over time of each major nuclide in spent fuel from a nuclear reactor. The dangerous nuclides decay quickly. Most longer-lived nuclides are less radioactive than natural uranium.[16]

How much waste is produced compared to other sources of energy? How will it be contained, and what are the dangers to people and the environment? Like questions on safety, public perception of the dangers of nuclear waste is much worse than historical data shows.[17] The volume of waste per terawatt-hour is 100,000 times less than coal.[18] Even if only looking at radioactivity released to the environment,[19] watt-for-watt nuclear power is 100 times less than coal.[20]

Much of the worry about nuclear waste centers around the long life of some low-level [21] isotopes in the waste (See Fig.4). There is concern about leakage into the environment decades or even centuries from now. Billion-dollar efforts to bury the waste deep under a mountain have only heightened public fears. Dry-cask storage at the power plants has proven to be a safe but temporary solution.[22] This interim storage has the advantage of being able to recover the "waste" and burn it in newer reactors that can use the remaining 97% of available energy.[23]

Transportation of spent fuel from reactors to disposal or reprocessing sites must be done safely. Reprocessing should be done at secure locations to avoid diversion of dangerous materials.[24] Leakage into groundwater and ocean water near shore is a special concern. New reactor designs must address these concerns, even though they go beyond the design of the reactor itself. Will the waste be solid or liquid? Will it require special casks, or even special vehicles for transportation on public roads? (See Fig.5)

© Photo: Nuclear Fuel Transport Ltd.
Fig.5 Transport of Nuclear Fuel in Japan.[25]

Other worries include the possibility of sabotage or theft of waste material that might be useful in a "dirty bomb". Again, regulators should evaluate specific plans by considering likely scenarios. Is the storage facility away from any population center and not a target for an airplane crash, a truck bomb, or even a short-range missile? Is there a secure perimeter with intrusion detectors? If there is an intrusion, is cutting through the concrete and steel difficult enough that there will be plenty of time for a response from local law enforcement, or even a nearby military base? (See Fig.6)

© Image: Holtec International
Fig.6 Dry underground storage in the desert, safe but still recoverable.

It is important to make a distinction between spent fuel from nuclear power, and the waste from bomb production, which was often done in a rush with little concern for pollution. Spent fuel rods can be stored safely. Weapons waste poses a much bigger problem due to the large variety and sometimes unexpected characteristics of the material to be buried.[26] In evaluating a new reactor design, regulators must look at the complete fuel cycle, not just the waste from the reactor itself. Are there any problems with the mining, processing, or transportation of the fuel, or with the reprocessing of spent fuel?

See also Nuclear_waste_management.

Weapons Proliferation

Will deployment of reactors to untrusted countries, or countries that might be taken over by rogue actors, increase the risk of proliferation, either by theft of materials in the reactor, or by modification of the reactor to produce weapons-grade materials? Will fuel processing or other activities connected with nuclear power provide cover for a weapons program or a basis for a quick sprint to bomb making? Will knowledge of the new reactor designs or process technologies lead to easier ways to make bombs?

There are three nuclides with potential for making a bomb: U-233, U-235, and Pu-239. Every reactor design has a characteristic isotopic composition in its fuel, which evolves over time as the fuel is consumed. Some uranium reactors have a brief period in their fuel cycle where weapons-grade Pu-239 can be extracted from the partially used fuel. Some thorium reactors with on-site fuel processing may be vulnerable to skimming of a small fraction of U-233 from the process loop.[27] Some molten salt reactors start with uranium enriched to 20% U-235, and that might provide a head-start to a country wanting to enrich all the way to bomb-grade.

Considerations like these favor designs in which all fuel processing is done at secure locations, and there is never any weapons grade material easily extracted from an operating reactor. The requirement should not be perfection, but simply that a new reactor should not allow an easier route to bomb making than currently available centrifuges.

See also Nuclear_proliferation

Cost

How will the cost compare to existing power sources including wind and solar? Existing nuclear plants have been very expensive, due to the inherent risks in Pressurized Water Reactors (PWR's) and the need for expensive structures and burdensome regulations to deal with that risk. Newer designs promise to be simpler, safer, and manufactured on an assembly line as replaceable parts, rather than site built. Elimination of water at high pressure and temperature avoids the risk of steam explosions. Reactor vessels with non-destructive "meltdown" behavior avoid the risk of another Fukushima.[28]

Plants with replaceable parts can operate indefinitely,[29] but if a plant is decommissioned, the process is little more than pulling out but not replacing all the parts. Cost is a lesser worry than the other issues, because the risk can be born by private companies promising to deliver reactors at an agreed price.[30] See Cost_of_nuclear_power for further discussion.

One remaining worry is future costs if fuel or some essential material becomes scarce. Some PWR's require hafnium in their control rods, and there was worry about the world supply of hafnium if thousands of these reactors were to be deployed in the coming decades.[31] As for the supply of fuel, the World Nuclear Association says it is essentially unlimited.[32] Some of the new reactors can burn[33] all the uranium, not just the 0.7% now burned by PWRs, and they can even burn thorium, which is three times more abundant than uranium.

See also Cost_of_nuclear_power.

New Reactor Designs

Here is a brief summary of several reactor types and representative examples of each type. See the specific reactor designs for responses to the issues raised in this article.

Small Modular Reactors

Small Modular Reactors (SMRs) include any type of reactor that is smaller than a conventional reactor, can be built as modules on an assembly line, delivered to the site where power is needed, and returned for recycling or disposal. The first SMR to be licensed in the United States [34] was the NuScale SMR, a smaller version of a standard Pressurized Water Reactor (PWR) with additional safety features.[35] NuScale has unfortunately failed to meet its promise of low cost.[36]

Molten Salt Reactors

Molten Salt Reactors (MSRs) provide higher temperature and better thermal efficiency than PWRs, while avoiding the risk of meltdown and high-pressure steam explosions inherent in PWRs. The ThorCon nuclear reactor is an MSR based on proven technology, intended for a short-term solution (decades) while more advanced designs are perfected.[37]

Fast Neutron Reactors

Fast Neutron Reactors (FNRs) are capable of burning spent nuclear fuel, old bomb cores, depleted uranium, and thorium. FNRs can breed more fissile material than they consume,[38] making them the current best bet for long-term energy sustainability.[39] This technology is not speculative, as are fusion [40] and new breakthroughs in storage. The Integral Fast Reactor is a metal-fueled, sodium-cooled, pool-type FNR.

Fig.7 Zero-carbon, very high-temperature process heat will be needed for some industries.

High Temperature Gas-cooled Reactors

High Temperature Gas-cooled Reactors (HTGRs) use inert helium gas as a coolant and can provide temperatures even higher than MSRs. These reactors may prove useful for industries needing zero-carbon, high-temperature process heat, like the production of hydrogen from water and the refining of steel. See Figure 7.

Further Reading

  • Electrifying Our World Dr.Robert Hargraves' excellent overview of energy, the growth human civilization, and possible solutions to the problems of energy poverty and global warming.
  • What is Nuclear Energy Dr. Nick Touran's easy introduction to nuclear energy by a group of nuclear engineers.
  • World Nuclear Information Library a comprehensive, authoritative collection of information on nuclear energy.
  • Our World in Data has a section on Energy and Environment with nice interactive graphics.
  • Gordian Knot News a collection of well-researched articles by Jack Devanney, an engineer with long experience in the nuclear industry.

Notes and References

  1. Global Energy Growth by Our World In Data
  2. Public figures who have reconsidered their stance on nuclear power are listed on the External Links tab of this article.
  3. Pumped storage is currently the most economical way to store electricity, but it requires a large reservoir on a nearby hill or in an abandoned mine. Li-ion battery systems at $500 per KWh are not practical for utility-scale storage. See Energy Storage for a summary of other alternatives.
  4. Utilities that include wind and solar power in their grid must have non-intermittent generating capacity (typically fossil fuels) to handle maximum demand for several days. They can save on fuel, but the cost of the plant is the same with or without intermittent sources.
  5. Mark Jacobson believes that long-distance transmission lines can provide an alternative to costly storage. See the bibliography for more on this proposal and the critique by Christopher Clack.
  6. "Load following" is the term used by utilities, and is important when there is a lot of wind and solar on the grid. Some reactors are not able to do this.
  7. Fig.1.3 in Devanney "Why Nuclear Power has been a Flop"
  8. Heat from electricity is very inefficient. Using nuclear heat directly from a reactor is possible for many industrial processes.
  9. Generation of hydrogen for fuel is possible with a Very High Temperature Reactor.
  10. Our World in Data - What are the safest and cleanest sources of energy?
  11. See Fear_of_radiation for discussion of these fears and the evidence contradicting widely-held beliefs about the dangers of nuclear power.
  12. Cybersecurity is an increasing risk for control systems connected to the Internet. See the WNA assessment of the threat from cyberspace.
  13. A common test for "walkaway safe" is to shut off all safety systems, including emergency cooling, jam the rods full throttle, and see what happens.Integral Fast Reactor Safety Test
  14. Requiring this level of safety may be unreasonable. See Al Scott's argument against "disaster porn" on the Debate Guide page.
  15. El Chapo's escape
  16. https://blogs.egu.eu/network/geosphere/2015/02/02/geopoll-what-should-we-do-with-radioactive-waste/
  17. “Over the last 40 years, thousands of shipments of commercially generated spent nuclear fuel have been made throughout the United States without causing any radiological releases to the environment or harm to the public.” - statement by the Nuclear Regulatory Commission quoted in Storage and Disposal of Radioactive Waste
  18. section 2.2 "A Beautifully Small Problem" in the book Why Nuclear Power has been a Flop.
  19. Radioactive Wastes From Coal-fired Power Plants US Environmental Protection Agency
  20. https://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/ - The title is a bit misleading. From the article: "In fact, the fly ash emitted by a power plant—a by-product from burning coal for electricity—carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy." "ounce for ounce, coal ash released from a power plant delivers more radiation than nuclear waste shielded via water or dry cask storage."
  21. Long-lived isotopes in spent nuclear fuel have both lower intensity and lower penetrating power than the short-lived fission products that are gone in 600 years. See the Nuclear Waste Lasts Forever section of the Debate Guide page of our Nuclear Waste Management article.
  22. Connecticut Yankee, a 619 MWe reactor on the Connecticut River, ran for 28 years between 1968 and 1996. The spent fuel from those 28 years is stored in 43 casks on a concrete pad, 70 feet by 228 feet.
  23. If we include in recoverable energy the depleted uranium produced in the enrichment process, we are using only 0.5% of the available energy. Fast Neutron Reactors with reprocessing could be 200 times more efficient in use of our mined uranium resources.
  24. See Processing of Used Nuclear Fuel for discussion of various reprocessing methods and their ability to separate fissile materials from the waste.
  25. Transport of Radioactive Materials World Nuclear Association
  26. A barrel containing plutonium mixed with kitty litter ruptured after it was stored at the Waste Isolation Pilot Plant, leading to "Nuclear accident in New Mexico ranks among the costliest in U.S. history" LA Times
  27. Thorium fuel has risks, Ashley 2012, https://www.nature.com/articles/492031a
  28. A liquid fuel reactor can have plugs at the bottom of the reactor vessel that melt if the reactor gets too hot. The fuel then flows safely into drain tanks.
  29. Elimination of "decommissioning" costs will greatly improve the long-term economy of nuclear plants Can Nuclear Plants be Immortal, Mark Nelson
  30. ThorCon has presented a detailed analysis showing the cost of their proposed plants as less than a coal plant.
  31. D. Abbott, "Is Nuclear Power Globally Scalable?" Proceedings of the IEEE, vol. 99, no. 10, pp. 1611-1617, Oct. 2011, https://ieeexplore.ieee.org/document/6021978. See section XIII on the hafnium problem.
  32. Supply of Uranium World Nuclear Association. See also Abbott 2011 for a counter-argument to the WNA assessment.
  33. The fissioning of nuclear fuel, sometimes called "burning" should not be confused with ordinary chemical reactions like oxidation that occurs when fossil fuels are burned.
  34. US nuclear regulator greenlights its first small modular reactor August 2022.
  35. https://www.science.org/news/2019/02/smaller-safer-cheaper-one-company-aims-reinvent-nuclear-reactor-and-save-warming-planet
  36. See Jack Devanney's article on the failure of NuScale.
  37. https://thorconpower.com/docs/docs_v130_isle20190315.pdf
  38. Breeding (the conversion of "fertile" to "fissile" isotopes) can multiply the amount of usable fuel by a factor of a hundred. See section 5.2 The Fuel Choice in Plentiful Energy, Till & Chang 2011 ISBN: 978-1466384606.
  39. The leading alternative (wind and solar) will require a breakthrough in storage technology.
  40. The most recent "breakthrough" in fusion, a "breakeven" demonstration (fusion energy out = laser energy in) is still a factor of 100 short of breakeven on electrical energy in vs electrical energy out. Nobody has even a conceptual design for a laser fusion plant costing less than a trillion dollars.
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