Archive for the ‘TECHNOLOGY’ Category

The US Energy Department’s renewed promotion of plutonium-fueled reactors. 

May 3, 2021

Plutonium programs in East Asia and Idaho will challenge the Biden administration, Bulletin of the Atomic Scientists, By Frank N. von Hippel | April 12, 2021  ”’…………. The US Energy Department’s renewed promotion of plutonium-fueled reactors. The US plutonium breeder reactor development program was ended by Congress in 1983. A decade later, the Clinton Administration shut down the Idaho National Laboratory’s Experimental Breeder Reactor II for lack of mission. At the time, I was working in the White House and supported that decision.

The nuclear-energy divisions at the Energy Department’s Argonne and Idaho National Laboratories refused to give up, however. They continued to produce articles promoting sodium-cooled reactors and laboratory studies on “pyroprocessing,” a small-scale technology used to separate plutonium from the fuel of the Experimental Breeder Reactor II .

During the Trump administration, this low-level effort broke out. With the Energy Department’s Office of Nuclear Energy headed by a former Idaho National Lab staffer and help from Idaho’s two Senators, the Energy Department and Congress were persuaded to approve the first steps toward construction at the Idaho National Laboratory of a larger version of the decommissioned Experimental Breeder Reactor II.

 The new reactor, misleadingly labeled the “Versatile Test Reactor,” would be built by Bechtel with design support by GE-Hitachi and Bill Gates’ Terrapower. The Energy Department awarded contracts to the Battelle Energy Alliance and to university nuclear-engineering departments in Indiana, Massachusetts, Michigan, and Oregon to develop proposals for how to use the Versatile Test Reactor.

The current estimated cost of the Versatile Test Reactor is $2.6-5.8 billion, and it is to be fueled with plutonium. The Idaho National Laboratory’s hope is to convince Congress to commit to funding its construction in 2021.

The Energy Department also committed $80 million to co-fund the construction of a 345-megawatt-electric (MWe) “Natrium” (Latin for sodium) demonstration liquid-sodium-cooled power reactor proposed by GE-Hitachi and Terrapower which it hopes Congress would increase to $1.6 billion. It also committed $25 million each to Advanced Reactor Concepts and General Atomics to design small sodium-cooled reactors. And it has subsidized Oklo, a $25-million startup company financed by the Koch family, to construct a 1.5 MWe “microreactor” on the Idaho National Laboratory’s site to demonstrate an extravagantly costly power source for remote regions.


In all these reactors, the chain reaction would be sustained by fast neutrons unlike the slow neutrons that sustain the chain reactions in water-cooled reactors. The Energy Department’s Office of Nuclear Energy has justified the need for the Versatile Test Reactor by the fast-neutron reactors whose construction it is supporting. In this way, it has “bootstraping” the Versatile Test Reactor by creating a need for it that would not otherwise exist.

This program also is undermining US nonproliferation policy..………..https://thebulletin.org/2021/04/plutonium-programs-in-east-asia-and-idaho-will-challenge-the-biden-administration/?utm_source=Newsletter&utm_medium=Email&utm_campaign=MondayNewsletter04122021&utm_content=NuclearRisk_EastAsia_04122021

Japan’s hugely costly nuclear reprocessing program.

May 3, 2021

Plutonium programs in East Asia and Idaho will challenge the Biden administration, Bulletin of the Atomic Scientists, By Frank N. von Hippel | April 12, 2021,  ”………………Japan’s hugely costly reprocessing program. The United States has been trying to persuade Japan to abandon reprocessing ever since 1977. At the time, then prime minister Takeo Fukuda described plutonium breeder reactors as a matter of “life and death” for Japan’s energy future and steamrolled the Carter administration into accepting the startup of Japan’s pilot reprocessing plant. Today, Japan is the only non-nuclear-armed state that separates plutonium. Despite the absence of any economic or environmental justification, the policy grinds ahead due to a combination of bureaucratic commitments and the dependence of a rural region on the jobs and tax income associated with the hugely costly program. The dynamics are similar to those that have kept the three huge US nuclear-weapon laboratories flourishing despite the end of the Cold War.

For three decades, Japan has been building, fixing mistakes, and making safety upgrades on a large plutonium recycle complex in Rokkasho Village in the poor prefecture of Aomori on the northern tip of the main island, Honshu. The capital cost of the complex has climbed to $30 billion. Operation of the reprocessing plant is currently planned for 2023.

A facility for fabricating the recovered plutonium into mixed-oxide plutonium-uranium fuel for water-cooled power reactors is under construction on the same site (Figure 3 on original). The cost of operating the complex is projected to average about $3 billion per year. Over the 40-year design life of the plant, it is expected to process about 300 tons of plutonium—enough to make 40,000 Nagasaki bombs. What could possibly go wrong?

Japan’s Atomic Energy Commission reports that, because of the failures and delays of its plutonium useage programs, as of the end of 2019, Japan owned a stock of 45.5 tons of separated plutonium: 9.9 tons in Japan with the remainder in France and the United Kingdom where Japan sent thousands of tons of spent fuel during the 1990s to be reprocessed.

Both the Obama and Trump administrations pressed Tokyo to revise its reprocessing policy, especially after Japan’s decision to decommission its failed prototype breeder reactor in 2016.

Perhaps in response to this pressure, in 2018, Japan’s cabinet declared:

“The Japanese government remains committed to the policy of not possessing plutonium without specific purposes on the premise of peaceful use of plutonium and work[s] to reduce of the size of [its] plutonium stockpile.”

A step toward reductions that is being discussed would be for Japan to pay the United Kingdom to take title to and dispose of the 22 tons of Japanese plutonium stranded there after the UK mixed-oxide fuel fabrication plant was found to be inoperable. Japan’s separated plutonium in France is slowly being returned to Japan in mixed-oxide fuel for use in reactors licensed to use such fuel.

If, as currently planned, Japan operates the Rokkasho Reprocessing Plant at its design capacity of more than seven tons of plutonium separated per year, however, its rate of plutonium separation will greatly exceed Japan’s rate of plutonium use.  Four of Japan’s currently operating reactors are licensed to use mixed-oxide fuel but loaded only 40 percent as much mixed-oxide fuel as planned in 2018-19 and none in 2020. Two more reactors that can use mixed-oxide are expected to receive permission to restart in the next few years. In 2010, Japan’s Federation of Electric Power Companies projected that the six reactors would use 2.6 tons of plutonium per year. If the much-delayed Ohma reactor, which is under construction and designed to be able to use a full core of mixed-oxide fuel, comes into operation in 2028 as currently planned, and all these reactors use as much mixed-oxide fuel as possible, Japan’s plutonium usage rate would still ramp up to only 4.3 tons per year in 2033. (At the end of 2020 the Federation of Electric Power Companies announced its hope to increase the number of mixed-oxide-using reactors to 12 by 2030 but did not list the five additional reactors, saying only, “we will release it as soon as it is ready.”)

As of June 2020, construction at Rokkasho on the mixed-oxide fuel fabrication facility that will process the plutonium separated by the Rokkasho Reprocessing Plant was only 12 percent complete. It was still just a hole in the ground containing some concrete work with its likely completion years behind the currently planned 2023 operation date of the reprocessing plant.

Thus, as happened in Russia and the United Kingdom, the Rokkasho Reprocessing Plant could operate indefinitely separating plutonium without the mixed-oxide plant operating. The reprocessing plant includes storage for “working stocks” containing up to 30 tons of unirradiated plutonium. If and when it begins operating, the mixed-oxide fuel fabrication plant will itself have additional working stocks of at least several tons of plutonium. Therefore, even if Japan transfers title to the plutonium it has stranded in the United Kingdom and manages to work down its stock in France, the growth of its stock in Japan could offset those reductions.

The Biden administration should urge Japan’s government to “bite the bullet” and begin the painful but necessary process of unwinding its costly and dangerous plutonium program. A first step would be to change Japan’s radioactive waste law to allow its nuclear utilities to use the planned national deep repository for direct disposal of their spent fuel.

In the meantime, most of Japan’s spent fuel will have to be stored on site in dry casks, as has become standard practice in the United States and most other countries with nuclear power reactors. Because of its safety advantages relative to storage in dense-packed pools, the communities that host Japan’s nuclear power plant are moving toward acceptance of dry-cask storage. During the 2011 Fukushima accident, the water in a dense-packed pool became dangerously low. Had the spent fuel been uncovered and caught on fire, the population requiring relocation could have been ten to hundreds of times larger ………….https://thebulletin.org/2021/04/plutonium-programs-in-east-asia-and-idaho-will-challenge-the-biden-administration/?utm_source=Newsletter&utm_medium=Email&utm_campaign=MondayNewsletter04122021&utm_content=NuclearRisk_EastAsia_04122021

USA’s nuclear rocket plan, and the Nazi history behind it.

May 3, 2021


The US plans to put a nuclear-powered rocket in orbit by 2025,  David Hambling.. (subscribers only)
https://www.newscientist.com/article/2274199-the-us-plans-to-put-a-nuclear-powered-rocket-in-orbit-by-2025/#ixzz6rrl4rEGB

The United States collaborates on nuclear pyroprocessing with South Korea.

May 3, 2021

Plutonium programs in East Asia and Idaho will challenge the Biden administration, Bulletin of the Atomic Scientists, By Frank N. von Hippel | April 12, 2021,  ”…………………………………The United States collaborates on pyroprocessing with South Korea. The Idaho and Argonne National Laboratories also continue to promote the pyroprocessing of spent fuel. After the Clinton Administration shut down the Experimental Breeder Reactor II in 1994, the laboratory persuaded the Energy Department to continue to fund pyroprocessing as a way to process Experimental Breeder Reactor II spent fuel and blanket assemblies into stable waste forms for disposal in a deep underground repository. The proposal was to complete this effort in 2007. According to a review by Edwin Lyman of the Union of Concerned Scientists, however, as of the end of Fiscal Year 2016, only about 18 percent of the roughly 26 metric tons of assemblies had been processed at a cost of over $200 million into waste forms that are not stable. (Since then, an additional three percent has been processed.)

During the George W. Bush administration, Vice President Cheney accepted Argonne’s argument that pyroprocessing is “proliferation resistant” and the two US national laboratories were allowed to share the technology with the Korea Atomic Energy Research Institute.

At the beginning of the Obama administration, however, a group of safeguards experts from six Energy Department national laboratories, including Argonne and Idaho, concluded that pyroprocessing is not significantly more resistant to proliferation than PUREX, the standard reprocessing technology originally developed by the United States to extract plutonium for its weapons.

In 2014, the US-Republic of Korea Agreement for Cooperation on the Peaceful Uses of Atomic Energy was due to expire, but the negotiations on a successor agreement bogged down over Korea’s insistence that the new agreement include the same right to reprocess spent fuel as the 1988 US-Japan Agreement for Cooperation.

The compromise reached the following year was that the Korea Atomic Energy Research Institute and the Idaho National Laboratory would complete their Joint Fuel Cycle Study on “the technical, economic, and nonproliferation (including safeguards) aspects of spent fuel management and disposition technologies.” If the United States could be convinced that the proliferation risks of pyroprocessing were manageable, the secretary of energy would give consent for South Korea to use the technology on its territory. The final report from the joint study is due this year.

Meanwhile, in 2017, Moon Jae-in was elected president of the Republic of Korea on a platform that included not building any more nuclear power plants in South Korea. Fast-neutron reactors and pyroprocessing obviously do not fit with that policy. This gives the Biden administration an opportunity to end a cooperative nuclear-energy research and development program that is contrary to both US nuclear nonproliferation policy and South Korea’s energy policy. The United States could propose instead a joint collaborative program on safe spent fuel storage and deep underground disposal……………https://thebulletin.org/2021/04/plutonium-programs-in-east-asia-and-idaho-will-challenge-the-biden-administration/?utm_source=Newsletter&utm_medium=Email&utm_campaign=MondayNewsletter04122021&utm_content=NuclearRisk_EastAsia_04122021

Assessing types of Non-Light-Water Nuclear Reactors

May 3, 2021

Assessing the Safety, Security, and Environmental Impacts of Non-Light-Water Nuclear Reactors, Union of Concerned Scientists, Edwin Lyman,  Mar 18, 2021

“Advanced” Isn’t Always Better

”………………..Assessments of NLWR Types

UCS has reviewed hundreds of documents in the available literature to assess the comparative risks and benefits of the three major categories of NLWR with respect to the three evaluation criteria (Table 2 on original).

Sodium-Cooled Fast Reactors

Safety and Security Risk: SFRs have numerous safety problems that are not issues for LWRs. Sodium coolant can burn if exposed to air or water, and an SFR can experience rapid power increases that may be hard to control. It is even possible that an SFR core could explode like a small nuclear bomb under severe accident conditions. Of particular concern is the potential for a runaway power excursion: if the fuel overheats and the sodium coolant boils, an SFR’s power will typically increase rapidly rather than decrease, resulting in a positive feedback loop that could cause core damage if not quickly controlled.

Chernobyl Unit 4 in the former Soviet Union, although not a fast reactor, had a similar design flaw—known as a “positive void coefficient.” It was a major reason for the reactor’s catastrophic explosion in 1986. A positive void coefficient is decidedly not a passive safety feature—and it cannot be fully eliminated by design in commercial-scale SFRs. To mitigate these and other risks, fast reactors should have additional engineered safety systems that LWRs do not need, which increases capital cost.

Sustainability: Because of the properties of fast neutrons, fast reactors do offer, in theory, the potential to be more sustainable than LWRs by either using uranium more efficiently or reducing the quantity of TRU elements present in the reactor and its fuel cycle. This is the only clear advantage of fast reactors compared with LWRs. However once-through fast reactors such as the Natrium being developed by TerraPower, a company founded and supported by Bill Gates, would be less uranium-efficient than LWRs. To significantly increase sustainability, most fast reactors would require spent fuel reprocessing and recycling, and the reactors and associated fuel cycle facilities would need to operate continuously at extremely high levels of performance for many hundreds or even thousands of years. Neither government nor industry can guarantee that future generations will continue to operate and replace these facilities indefinitely. The enormous capital investment needed today to build such a system would only result in minor sustainability benefits over a reasonable timeframe.

Nuclear Proliferation/Terrorism: Historically, fast reactors have required plutonium or HEU-based fuels, both of which could be readily used in nuclear weapons and therefore entail unacceptable risks of nuclear proliferation and nuclear terrorism. Some SFR concepts being developed today utilize HALEU instead of plutonium and could operate on a once-through cycle. These reactors would pose lower proliferation and security risks than would plutonium-fueled fast reactors with reprocessing, but they would have many of the same safety risks as other SFRs. And, as pointed out, most once-through SFRs would actually be less sustainable than LWRs and thus unable to realize the SFR’s main benefit. For this reason, these once-through SFRs are likely to be “gateway” reactors that would eventually transition to SFRs with reprocessing and recycling. The only exceptions—if technically feasible—are once-through fast reactors operating in breed-and-burn mode. However, the only breed-and-burn reactor that has undergone significant R&D, TerraPower’s “traveling-wave reactor,” was recently suspended after more than a decade of work, suggesting that its technical challenges proved too great.

High-Temperature Gas-Cooled Reactors

Safety and Security Risk: HTGRs have some attractive safety features but also a number of drawbacks. Their safety is rooted in the integrity of TRISO fuel, which has been designed to function at the high normal operating temperature of an HTGR (up to 800ºC) and can retain radioactive fission products up to about 1,600ºC if a loss-of-coolant accident occurs. However, if the fuel heats up above that temperature—as it could in the Xe-100—its release of fission products speeds up significantly. So, while TRISO has some safety benefits, the fuel is far from meltdown-proof, as some claim. Indeed, a recent TRISO fuel irradiation test in the Advanced Test Reactor in Idaho had to be terminated prematurely when the fuel began to release fission products at a rate high enough to challenge off-site radiation dose limits.

The performance of TRISO fuel also depends critically on the ability to consistently manufacture fuel to exacting specifications, which has not been demonstrated. HTGRs are also vulnerable to accidents in which air or water leaks into the reactor; this is much less of a concern for LWRs. And the moving fuel in pebble-bed HTGRs introduces novel safety issues.

Despite these unknowns, HTGRs are being designed without the conventional leak-tight containments that LWRs have—potentially cancelling out any inherent safety benefits provided by the design and fuel. Given the uncertainties, much more testing and analysis are necessary to determine conclusively if HTGRs would be significantly safer than LWRs.

Sustainability: HTGRs are less sustainable than LWRs overall. They use uranium no more efficiently due to their use of HALEU, and they generate a much larger volume of highly radioactive waste. Although pebble-bed HTGRs are somewhat more flexible and uranium-efficient than prismatic-block HTGRs, the difference is not enough to overcome the penalty from using HALEU fuel.

Nuclear Proliferation/Terrorism: HTGRs raise additional proliferation issues compared with LWRs. Current HTGR designs use HALEU, which poses a greater security risk than the LEU grade used by LWRs, and TRISO fuel fabrication is more challenging to monitor than LWR fuel fabrication. Also, it is difficult to accurately account for nuclear material at pebble-bed HTGRs because fuel is continually fed into and removed from the reactor as it operates. On the other hand, it may be more difficult for a proliferator to reprocess TRISO spent fuel than LWR spent fuel to extract fissile material because the required chemical processes are less mature.

Molten Salt-Fueled Reactors

Safety and Security Risk: MSR advocates point to the fact that this type of reactor cannot melt down—the fuel is already molten. However, this simplistic argument belies the fact that MSR fuels pose unique safety issues. Not only is the hot liquid fuel highly corrosive, but it is also difficult to model its complex behavior as it flows through a reactor system. If cooling is interrupted, the fuel can heat up and destroy an MSR in a matter of minutes. Perhaps the most serious safety flaw is that, in contrast to solid-fueled reactors, MSRs routinely release large quantities of gaseous fission products, which must be trapped and stored. Some released gases quickly decay into troublesome radionuclides such as cesium-137— the highly radioactive isotope that caused persistent and extensive environmental contamination following the Chernobyl and Fukushima nuclear accidents.

Sustainability: A main argument for MSRs is that they are more flexible and can operate more sustainably than reactors using solid fuel. In theory, some MSRs would be able to use natural resources more efficiently than LWRs and generate lower amounts of long-lived nuclear waste. However, the actual sustainability improvements for a range of thermal and fast MSR designs are too small, even with optimistic performance assumptions, to justify their high safety and security risks.

Nuclear Proliferation/Terrorism: MSRs present unique challenges for nuclear security because it would be very difficult to account for nuclear material accurately as the liquid fuel flows through the reactor. In addition, some designs require on-site, continuously operating fuel reprocessing plants that could provide additional pathways for diverting or stealing nuclear-weapon-usable materials.

MSRs could also endanger global nuclear security by interfering with the worldwide network of radionuclide monitors put into place to verify compliance with the Comprehensive Nuclear Test Ban Treaty after it enters into force.5 MSRs release vast quantities of the same radioactive xenon isotopes that are signatures of clandestine nuclear explosions—an issue that MSR developers do not appear to have addressed. It is unclear whether it would be feasible or affordable to trap and store these isotopes at MSRs to the degree necessary to avoid degrading the effectiveness of the monitoring system to detect treaty violations.

Safely Commercializing NLWRs: Timelines and Costs

Can NLWRs be deployed quickly enough to play a significant role in reducing carbon emissions and avoiding the worst effects of climate change? The 2018 special report of the UN’s Intergovernmental Panel on Climate Change identified 85 energy supply pathways to 2050 capable of achieving the Paris Agreement target of limiting global mean temperature rise to 1.5°C. The median capacity of nuclear power in 2050 across those pathways is about 150 percent over the 2020 level. Taking into account planned retirements, this corresponds to the equivalent of at least two dozen 1,000 MWe reactors coming online globally each year between now and 2050— five times the recent global rate of new LWR construction. If the world must wait decades for NLWRs to be commercially available, they would have to be built even faster to fill the gap by 2050.

Some developers of NLWRs say that they will be able to meet this challenge by deploying their reactors commercially as soon as the late 2020s. However, such aggressive timelines are inconsistent with the recent experience of new reactors such as the Westinghouse AP1000, an evolutionary LWR. Although the AP1000 has some novel features, its designers leveraged many decades of LWR operating data. Even so, it took more than 30 years of research, development, and construction before the first AP1000—the Sanmen Unit 1 reactor in China—began to produce power in 2018.

How, then, could less-mature NLWR reactors be commercialized so much faster than the AP1000? At a minimum, commercial deployment in the 2020s would require bypassing two developmental stages that are critical for assuring safety and reliability: the demonstration of prototype reactors at reduced scale and at full scale. Prototype reactors are typically needed for demonstrating performance and conducting safety and fuel testing to address knowledge gaps in new reactor designs. Prototypes also may have additional safety features and instrumentation not included in the basic design, as well as limits on operation that would not apply to commercial units.

By a 2017 report, the DOE asserted that SFRs and HTGRs were mature enough for commercial demonstrations without the need for additional prototype testing. For either of these types, the DOE estimated it would cost approximately $4 billion and take 13 to 15 years to complete a first commercial demonstration unit, assuming that reactor construction and startup testing take seven years. After five years of operating the demonstration unit, additional commercial units could follow in the mid-2030s.

In contrast, for MSRs and other lower-maturity designs, the DOE report judged that both reduced-scale and full-scale prototypes (which the report referred to as “engineering” and “performance” demonstrations, respectively) would be needed before a commercial demonstration reactor could be built. These additional stages could add $2 billion to $4 billion to the cost and 20 years to the development timeline. The subsequent commercial demonstration would not begin until 2040; reactors would not be available for sale until the mid-2040s or even the 2050s.

In May 2020, after receiving $160 million in initial congressional funding for the new Advanced Reactor Demonstration Program (ARDP), the DOE issued a solicitation for two “advanced” commercial demonstration reactors. In October 2020, the DOE chose SFR and HTGR designs—as one might expect given its 2017 technology assessment. The DOE estimates that these projects will cost up to $3.2 billion each (with the vendors contributing 50 percent) for the reactors and their supporting fuel facilities. The department is requiring that the reactors be operational within seven years, a timeline—including NRC licensing, construction, fuel production, and startup testing—that it acknowledges is very aggressive.

However, even if this deadline can be met and the reactors work reliably, subsequent commercial units likely would not be ordered before the early 2030s. Moreover, it is far from certain that the two designs the DOE selected for the ARDP are mature enough for commercial demonstration. Past demonstrations of both SFRs and HTGRs have encountered safety and reliability problems. Additionally, for both reactor types, the DOE has chosen designs that differ significantly from past demonstration reactors.

In the 1990s, the NRC concluded that it would require information from representative prototype testing prior to licensing either of these reactor types—but no prototypes were ever built. More recently, in a letter to the NRC, the agency’s independent Advisory Committee on Reactor Safeguards reaffirmed the importance of prototypes in new reactor development. Nevertheless, the NRC—a far weaker regulator today—has apparently changed its position and may proceed with licensing the ARDP demonstration reactors without requiring prototype testing first. But by skipping prototype testing and proceeding directly to commercial units, these projects may run not only the risk of experincing unanticipated reliability problems, but also the risk of suffering serious accidents that could endanger public health and safety.

An additional challenge for NLWR demonstrations and subsequent commercial deployment is the availability of fuels for those reactors, which would differ significantly from the fuel that today’s LWRs use. Even a single small reactor could require a few tons of HALEU per year—far more than the 900 kilograms per year projected to be available over the next several years from a DOE-funded pilot enrichment plant that Centrus Energy Corporation is building in Piketon, Ohio. It is far from clear whether that pilot will succeed and can be scaled up in time to support the two NLWR demonstrations by 2027, not to mention the numerous other HALEU-fueled reactor projects that have been proposed……. https://ucsusa.org/resources/advanced-isnt-always-better#read-online-content

Conclusions and recommendations of safety assessment of advanced nuclear reactors – non-light-water ones

May 3, 2021

Assessing the Safety, Security, and Environmental Impacts of Non-Light-Water Nuclear Reactors,Union of Concerned Scientists, Edwin Lyman Mar 18, 2021  “Advanced” Isn’t Always Better  

”……….Conclusions of the Assessment

The non-light-water nuclear reactor landscape is vast and complex, and it is beyond the scope of this report to survey the entire field in depth. Nevertheless, enough is clear even at this stage to draw some general conclusions regarding the safety and security of NLWRs and their prospects for rapid deployment.

Based on the available evidence, the NLWR designs currently under consideration (except possibly once-through, breed-and-burn reactors) do not offer obvious improvements over LWRs significant enough to justify their many risks. Regulators and other policymakers would be wise to look more closely at the nuclear power programs under way to make sure they prioritize safety and security. Future appropriations for NLWR technology research, development, and deployment should be guided by realistic assessments of the likely societal benefits that would result from the investment of billions of taxpayer dollars.

Little evidence supports claims that NLWRs will be significantly safer than today’s LWRs. While some NLWR designs offer some safety advantages, all have novel characteristics that could render them less safe.

All NLWR designs introduce new safety issues that will require substantial analysis and testing to fully understand and address—and it may not be possible to resolve them fully. To determine whether any NLWR concept will be significantly safer than LWRs, the reactor must achieve an advanced stage of technical maturity, undergo complete comprehensive safety testing and analysis, and acquire significant operating experience under realistic conditions.

The claim that any nuclear reactor system can “burn” or “consume” nuclear waste is a misleading oversimplification. Reactors can actually use only a fraction of spent nuclear fuel as new fuel, and separating that fraction increases the risks of nuclear proliferation and terrorism.

No nuclear reactor can use spent nuclear fuel directly as fresh fuel. Instead, spent fuel has to be “reprocessed”—chemically treated to extract plutonium and other TRU elements, which must then be refabricated into new fuel. This introduces a grave danger: plutonium and other TRU elements can be used in nuclear weapons. Reprocessing and recycling render these materials vulnerable to diversion or theft and increases the risks of nuclear proliferation and terrorism—risks that are costly to address and that technical and institutional measures cannot fully mitigate. Any fuel cycle that requires reprocessing poses inherently greater proliferation and terrorism risks than the “once-through” cycle with direct disposal of spent fuel in a geologic repository.

Some NLWRs have the potential for greater sustainability than LWRs, but the improvements appear to be too small to justify their proliferation and safety risks.

Although some NLWR systems could use uranium more efficiently and generate smaller quantities of long-lived TRU isotopes in nuclear waste, for most designs these benefits could be achieved only by repeatedly reprocessing spent fuel to separate out these isotopes and recycle them in new fuel—and that presents unacceptable proliferation and security risks. In addition, reprocessing plants and other associated fuel cycle facilities are costly to build and operate, and they increase the environmental and safety impacts compared with the LWR once-through cycle. Moreover, the sustainability increases in practice would not be significant in a reasonably foreseeable time frame.

Once-through, breed-and-burn reactors have the potential to use uranium more efficiently without reprocessing, but many technical challenges remain.

One type of NLWR system that could in principle be more sustainable than the LWR without increasing proliferation and terrorism risks is the once-through, breed-and-burn reactor. Concepts such as TerraPower’s traveling-wave reactor could enable the use of depleted uranium waste stockpiles as fuel, which would increase the efficiency of uranium use. Although there is no economic motivation to develop more uranium-efficient reactors at a time when uranium is cheap and abundant, reducing uranium mining may be beneficial for other reasons, and such reactors may be useful for the future. However, many technical challenges would have to be overcome to achieve breed-and-burn operation, including the development of very-high-burnup fuels. The fact that TerraPower suspended its project after more than a decade of development to pursue a more conventional and far less uranium-efficient SFR, the Natrium, suggests that these challenges have proven too great.

High-assay low enriched uranium (HALEU) fuel, which is needed for many NLWR designs, poses higher nuclear proliferation and nuclear terrorism risks than the lower-assay LEU used by the operating LWR fleet.

Many NLWR designs require uranium enriched to higher levels than the 5 percent U-235 typical of LWR fuel. Although uranium enriched to between 10 and 20 percent U-235 (defined here as HALEU) is considered impractical for direct use in nuclear weapons, it is more attractive for weapons use—and requires more stringent security—than the lower-assay enriched uranium in current LWRs.

The significant time and resources needed to safely commercialize any NLWR design should not be underestimated.

It will likely take decades and many billions of dollars to develop and commercially deploy any NLWR design, together with its associated fuel cycle facilities and other support activities. Such development programs would come with a significant risk of delay or failure and require long-term stewardship and funding commitments. And even if a commercially workable design were demonstrated, it would take many more years after that to deploy a large number of units and operate them safely and reliably.

Vendors that claim their NLWRs could be commercialized much more quickly typically assume that their designs will not require full-scale performance demonstrations and extensive safety testing, which could add well over a decade to the development timeline. However, current designs for sodium-cooled fast reactors and high-temperature gas-cooled reactors differ enough from past reactor demonstrations that they cannot afford to bypass additional full-scale prototype testing before licensing and commercial deployment. Molten salt–fueled reactors have only had small-scale demonstrations and thus are even less mature. NLWRs deployed commercially at premature stages of development run a high risk of poor performance and unexpected safety problems.

Recommendations

The DOE should suspend the advanced reactor demonstration program pending a finding by the NRC whether it will require full-scale prototype testing before licensing the two chosen designs as commercial power reactors.

The DOE has selected two NLWR designs, the Natrium SFR and the Xe-100 pebble-bed HTGR, for demonstration of full-scale commercial operation by 2027. However, the NRC has yet to evaluate whether these designs are mature enough that it can license them without first obtaining data from full-scale prototype plants to demonstrate novel safety features, validate computer codes, and qualify new types of fuel in representative environments. Without such an evaluation, the NRC will likely lack the information necessary to ensure safe, secure operation of these reactors. The DOE should suspend the Advanced Reactor Demonstration Program until the NRC—in consultation with the agency’s Advisory Committee on Reactor Safeguards and external experts—has determined whether prototypes will be needed first.

Congress should require that an independent, transparent, peer-review panel direct all DOE R&D on new nuclear concepts, including the construction of additional test or demonstration reactors.

Given the long time and high cost required to commercialize NLWR designs, the DOE should provide funding for NLWR R&D judiciously and only for reactor concepts that offer a strong possibility of significantly increasing safety and security—and do not increase proliferation risks. Moreover, unlike the process for selecting the two reactor designs for the Advanced Reactor Demonstration Program, decision-making should be transparent.6 Congress should require that the DOE convene an independent, public commission to thoroughly review the technical merits of all NLWR designs proposed for development and demonstration, including those already selected for the ARDP. The commission, whose members should represent a broad range of expertise and perspectives, would recommend funding only for designs that are highly likely to be commercialized successfully while achieving clearly greater safety and security than current-generation LWRs.

The DOE and other agencies should thoroughly assess the implications for proliferation and nuclear terrorism of the greatly expanded production, processing, and transport of the high-assay low-enriched uranium (HALEU) required to support the widespread deployment of NLWRs.

Large-scale deployment of NLWRs that use HALEU fuel will require establishing a new industrial infrastructure for producing and transporting the material. The DOE is actively promoting the development of HALEU-fueled reactor designs for export. Given that HALEU is a material of higher security concern than lower-assay LEU, Congress should require that the DOE immediately assess the proliferation and nuclear terrorism implications of transitioning to the widespread use of HALEU worldwide. This assessment should also address the resource requirements for the security and safeguards measures needed to ensure that such a transition can occur without an unacceptable increase in risk.

The United States should make all new reactors and associated fuel facilities eligible for IAEA safeguards and provide that agency with the necessary resources for carrying out verification activities.

The IAEA, which is responsible for verifying that civilian nuclear facilities around the world are not being misused to produce materials for nuclear weapons, has limited or no experience in safeguarding many types of NLWRs and their associated fuel cycle facilities. NLWR projects being considered for deployment in the United States, such as the Natrium SFR and the Xe-100 pebble-bed HTGR, would provide ideal test beds for the IAEA to develop safeguards approaches. However, as a nuclear-weapon state, the United States is not obligated to give the IAEA access to its nuclear facilities. To set a good example and advance the cause of nonproliferation, the United States should immediately provide the IAEA with permission and funding to apply safeguards on all new US nuclear facilities, beginning at the design phase. This would help to identify safeguard challenges early and give the IAEA experience in verifying similar facilities if they are deployed in other countries.

The DOE and Congress should consider focusing nuclear energy R&D on improving the safety and security of LWRs, rather than on commercializing immature NLWR designs.

LWR technology benefits from a vast trove of information resulting from many decades of acquiring experimental data, analysis, and operating experience—far more than that available for any NLWR. This gives the LWR a significant advantage over other nuclear technologies. The DOE and Congress should do a more thorough evaluation of the benefits of focusing R&D funding on addressing the outstanding safety, security, and cost issues of LWRs rather than attempting to commercialize less mature reactor concepts. If the objective is to expand nuclear power to help deal with the climate crisis over the next few decades, improving LWRs could be a less risky bet.

Endnotes………

This is a condensed, online version of the executive summary. For all figures, references, and the full text, please download the PDF.  https://ucsusa.org/resources/advanced-isnt-always-better#read-online-content

Nuclear reactors – “Advanced” Isn’t Always Better” – Non-Light-Water Nuclear Reactors

May 3, 2021

Assessing the Safety, Security, and Environmental Impacts of Non-Light-Water Nuclear Reactors,Union of Concerned Scientists, Edwin Lyman Mar 18, 2021  “Advanced” Isn’t Always Better  ”……………………….Key Questions for Assessing NLWR Technologies

It is critical that policymakers, regulators, and private investors fully vet the claims that the developers of NLWRs are making and accurately assess the prospects for both successful development_ and_ safe, secure, and cost-effective deployment. Given the urgency of the climate crisis, rigorous evaluation of these technologies will help our nation and others avoid wasting time or resources in the pursuit of high-risk concepts that would be only slightly better— or perhaps worse—than LWRs.

Key questions to consider are the following:

  • What are the benefits and risks of NLWRs and their fuel cycles compared with those of LWRs?
  • Do the likely overall benefits of NLWRs outweigh the risks and justify the substantial public and private investments needed to commercialize them?
  • Can NLWRs be safely and securely commercialized in time to contribute significantly to averting the climate crisis?

To help inform policy decisions on these questions, the Union of Concerned Scientists (UCS) has evaluated certain claims about the principal types of NLWRs. In particular, this report compares several classes of NLWRs to LWRs with regard to safety and security, the risks of nuclear proliferation and nuclear terrorism, and “sustainability”—a term that in this context includes the often-claimed ability of some NLWRs to “recycle” nuclear waste and use mined uranium more efficiently. The report also considers the potential for certain NLWRs to operate in a once-through, “breed-and-burn” mode that would, in theory, make them more uranium-efficient without the need to recycle nuclear waste—a dangerous process that has significant nuclear proliferation and terrorism risks.

Non-Light-Water Reactor Technologies

UCS considered these principal classes of NLWRs:

Sodium-cooled fast reactors (SFRs): These reactors are known as “fast reactors” because, unlike LWRs or other reactors that use lower-energy (or “thermal”) neutrons, the liquid sodium coolant does not moderate (slow down) the high-energy (or “fast”) neutrons produced when nuclear fuel undergoes fission. The characteristics and design features of these reactors differ significantly from those of LWRs, stemming from the properties of fast neutrons and the chemical nature of liquid sodium.

High-temperature gas–cooled reactors (HTGRs): These reactors are cooled by a pressurized gas such as helium and operate at temperatures up to 800ºC, compared with around 300ºC for LWRs. HTGR designers developed a special fuel called TRISO (tristructural isotropic) to withstand this high operating temperature. HTGRs typically contain graphite as a moderator to slow down neutrons. There are two main variants of HTGR. A prismatic-block HTGR uses conventional nuclear fuel elements that are stationary; in a pebble-bed HTGR, moving fuel elements circulate continuously through the reactor core.

Molten salt–fueled reactors (MSRs): In contrast to conventional reactors that use fuel in a solid form, these use liquid fuel dissolved in a molten salt at a temperature of at least 650ºC. The fuel, which is pumped through the reactor, also serves as the coolant. MSRs can be either thermal reactors that use a moderator such as graphite or fast reactors without a moderator. All MSRs chemically treat the fuel to varying extents while the reactor operates to remove radio-active isotopes that affect reactor performance. Therefore, unlike other reactors, MSRs generally require on-site chemical plants to process their fuel. MSRs also need elaborate systems to capture and treat large volumes of highly radioactive gaseous byproducts.

The Fuels for Non-Light-Water Reactors

Today’s LWRs use uranium-based nuclear fuel containing less than 5 percent of the isotope uranium-235. This fuel is produced from natural (mined) uranium, which has a uranium-235 content of less than 1 percent, in a complex industrial process called uranium enrichment. Fuel enriched to less than 20 percent U-235 is called “low-enriched uranium” (LEU). Experts consider it a far less attractive material for nuclear weapons development than “highly enriched uranium” (HEU), with a U-235 content of at least 20 percent.

The fuel for most NLWRs differs from that of LWRs. . Some proposed NLWRs would use LEU enriched to between 10 and 20 percent uranium-235; this is known as “high-assay low enriched uranium” (HALEU).2 While HALEU is considered impractical for direct use in a nuclear weapon, it is more attractive for nuclear weapons development than the LEU used in LWRs. Other types of NLWRs would use plutonium separated from spent nuclear fuel through a chemical process called reprocessing. Still others would utilize the isotope uranium-233 obtained by irradiating the element thorium. Both plutonium and uranium-233 are highly attractive for use in nuclear weapons.

Typically, the chemical forms of NLWR fuels also differ from those of conventional LWR fuel, which is a ceramic material composed of uranium oxide. Fast reactors can use oxides, but they can also use fuels made of metal alloys or chemical compounds such as nitrides. The TRISO fuel in HTGRs consists of tiny kernels of uranium oxide (or other uranium compounds) surrounded by several layers of carbon-based materials. MSR fuels are complex mixtures of fluoride or chloride salt compounds.

The deployment of NLWRs also would require new industrial facilities and other infrastructure to produce and transport their different types of fuel, as well as to manage spent fuel and other nuclear wastes. These facilities may use new technologies that themselves would require significant R&D. They also may present different risks related to safety, security, and nuclear proliferation than do LWR fuel cycle facilities—important considerations for evaluating the whole system.

Non-Light-Water Reactors: Past and Present

In the mid-20th century, the Atomic Energy Commission (AEC)—the predecessor of today’s Department of Energy (DOE) and the NRC—devoted considerable time and resources to developing a variety of NLWR technologies, supporting demonstration plants at various scales at sites around the United States. Owners of several of these reactors abandoned them after the reactors experienced operational problems (for example, the Fort St. Vrain HTGR in Colorado) or even serious accidents (the Fermi-1 SFR in Michigan).

Despite these negative experiences, the DOE continued R&D on various types of NLWR and their fuel cycles. In the 1990s, the DOE initiated the Generation IV program, with the goal of “developing and demonstrating advanced nuclear energy systems that meet future needs for safe, sustainable, environmentally responsible, economical, proliferation-resistant, and physically secure energy.” Although Generation IV identified six families of advanced reactor technology, the DOE has given most of its subsequent support to SFRs and HTGRs.

Today, a number of NLWR projects at various stages of development are under way, funded by both public and private sources (Table 1). With support from Congress, the DOE is pursuing several new NLWR test and demonstration reactors. It is proceeding with the design and construction of the Versatile Test Reactor (VTR), an SFR that it hopes to begin operating in the 2026–2031 timeframe. The VTR would not generate electricity but would be used to test fuels and materials for developing other reactors. In October 2020, the DOE selected two NLWR designs for demonstrating commercial power generation by 2027: the Xe-100, a small pebble-bed HTGR that would generate about 76 megawatts of electricity (MWe), and the 345 MWe Natrium, an SFR that is essentially a larger version of the VTR with a power production unit. The DOE is also providing funding for two smaller-scale projects to demonstrate molten salt technologies. In addition, the DOE, the Department of Defense (DOD), and a private company, Oklo, Inc., are pursuing demonstrations of so-called micro-reactors—very small NLWRs with capacities from 1 MWe to 20 MWe—and project that these will begin operating in the next few years. A number of universities also have expressed interest in building small NLWRs for research.

Congress would need to provide sufficient and sustained funding for any of these projects to come to fruition. This is far from assured—for example, funding for the VTR to date has fallen far short of what the DOE has requested, all but guaranteeing the project will be delayed.

The Goals of New Reactor Development

If nuclear power is to play an expanded global role to help mitigate climate change, new reactor designs should be demonstrably safer and more secure—and more economical—than the existing reactor fleet. Today’s LWRs remain far too vulnerable to Fukushima-like accidents, and the uranium enrichment plants that provide their LEU fuel can be misused to produce HEU for nuclear weapons. However, developing new designs that are clearly superior to LWRs overall is a formidable challenge, as improvements in one respect can create or exacerbate problems in others. For example, increasing the physical size of a reactor core while keeping its power generation rate constant could make the reactor easier to cool in an accident, but it could also increase cost.

Moreover, the problems of nuclear power cannot be fixed through better reactor design alone. Also critical is the regulatory framework governing the licensing, construction, and operation of nuclear plants and their associated fuel cycle infrastructure. Inadequate licensing standards and oversight activities can compromise the safety of improved designs. A key consideration is the extent to which regulators require extra levels of safety—known as “defense-in-depth”—to compensate for uncertainties in new reactor designs for which there is little or no operating experience………

This is a condensed, online version of the executive summary. For all figures, references, and the full text, please download the PDF.         https://ucsusa.org/resources/advanced-isnt-always-better#read-online-content

Assessing types of non-lightwater nuclear reactors

April 5, 2021

Assessing the Safety, Security, and Environmental Impacts of Non-Light-Water Nuclear Reactors, Union of Concerned Scientists, Edwin Lyman,  Mar 18, 2021

“Advanced” Isn’t Always Better

”………………..Assessments of NLWR Types

UCS has reviewed hundreds of documents in the available literature to assess the comparative risks and benefits of the three major categories of NLWR with respect to the three evaluation criteria (Table 2).

Sodium-Cooled Fast Reactors

Safety and Security Risk: SFRs have numerous safety problems that are not issues for LWRs. Sodium coolant can burn if exposed to air or water, and an SFR can experience rapid power increases that may be hard to control. It is even possible that an SFR core could explode like a small nuclear bomb under severe accident conditions. Of particular concern is the potential for a runaway power excursion: if the fuel overheats and the sodium coolant boils, an SFR’s power will typically increase rapidly rather than decrease, resulting in a positive feedback loop that could cause core damage if not quickly controlled.

Chernobyl Unit 4 in the former Soviet Union, although not a fast reactor, had a similar design flaw—known as a “positive void coefficient.” It was a major reason for the reactor’s catastrophic explosion in 1986. A positive void coefficient is decidedly not a passive safety feature—and it cannot be fully eliminated by design in commercial-scale SFRs. To mitigate these and other risks, fast reactors should have additional engineered safety systems that LWRs do not need, which increases capital cost.

Sustainability: Because of the properties of fast neutrons, fast reactors do offer, in theory, the potential to be more sustainable than LWRs by either using uranium more efficiently or reducing the quantity of TRU elements present in the reactor and its fuel cycle. This is the only clear advantage of fast reactors compared with LWRs. However once-through fast reactors such as the Natrium being developed by TerraPower, a company founded and supported by Bill Gates, would be less uranium-efficient than LWRs. To significantly increase sustainability, most fast reactors would require spent fuel reprocessing and recycling, and the reactors and associated fuel cycle facilities would need to operate continuously at extremely high levels of performance for many hundreds or even thousands of years. Neither government nor industry can guarantee that future generations will continue to operate and replace these facilities indefinitely. The enormous capital investment needed today to build such a system would only result in minor sustainability benefits over a reasonable timeframe.

Nuclear Proliferation/Terrorism: Historically, fast reactors have required plutonium or HEU-based fuels, both of which could be readily used in nuclear weapons and therefore entail unacceptable risks of nuclear proliferation and nuclear terrorism. Some SFR concepts being developed today utilize HALEU instead of plutonium and could operate on a once-through cycle. These reactors would pose lower proliferation and security risks than would plutonium-fueled fast reactors with reprocessing, but they would have many of the same safety risks as other SFRs. And, as pointed out, most once-through SFRs would actually be less sustainable than LWRs and thus unable to realize the SFR’s main benefit. For this reason, these once-through SFRs are likely to be “gateway” reactors that would eventually transition to SFRs with reprocessing and recycling. The only exceptions—if technically feasible—are once-through fast reactors operating in breed-and-burn mode. However, the only breed-and-burn reactor that has undergone significant R&D, TerraPower’s “traveling-wave reactor,” was recently suspended after more than a decade of work, suggesting that its technical challenges proved too great.

High-Temperature Gas-Cooled Reactors

Safety and Security Risk: HTGRs have some attractive safety features but also a number of drawbacks. Their safety is rooted in the integrity of TRISO fuel, which has been designed to function at the high normal operating temperature of an HTGR (up to 800ºC) and can retain radioactive fission products up to about 1,600ºC if a loss-of-coolant accident occurs. However, if the fuel heats up above that temperature—as it could in the Xe-100—its release of fission products speeds up significantly. So, while TRISO has some safety benefits, the fuel is far from meltdown-proof, as some claim. Indeed, a recent TRISO fuel irradiation test in the Advanced Test Reactor in Idaho had to be terminated prematurely when the fuel began to release fission products at a rate high enough to challenge off-site radiation dose limits.

The performance of TRISO fuel also depends critically on the ability to consistently manufacture fuel to exacting specifications, which has not been demonstrated. HTGRs are also vulnerable to accidents in which air or water leaks into the reactor; this is much less of a concern for LWRs. And the moving fuel in pebble-bed HTGRs introduces novel safety issues.

Despite these unknowns, HTGRs are being designed without the conventional leak-tight containments that LWRs have—potentially cancelling out any inherent safety benefits provided by the design and fuel. Given the uncertainties, much more testing and analysis are necessary to determine conclusively if HTGRs would be significantly safer than LWRs.

Sustainability: HTGRs are less sustainable than LWRs overall. They use uranium no more efficiently due to their use of HALEU, and they generate a much larger volume of highly radioactive waste. Although pebble-bed HTGRs are somewhat more flexible and uranium-efficient than prismatic-block HTGRs, the difference is not enough to overcome the penalty from using HALEU fuel.

Nuclear Proliferation/Terrorism: HTGRs raise additional proliferation issues compared with LWRs. Current HTGR designs use HALEU, which poses a greater security risk than the LEU grade used by LWRs, and TRISO fuel fabrication is more challenging to monitor than LWR fuel fabrication. Also, it is difficult to accurately account for nuclear material at pebble-bed HTGRs because fuel is continually fed into and removed from the reactor as it operates. On the other hand, it may be more difficult for a proliferator to reprocess TRISO spent fuel than LWR spent fuel to extract fissile material because the required chemical processes are less mature.

Molten Salt-Fueled Reactors

Safety and Security Risk: MSR advocates point to the fact that this type of reactor cannot melt down—the fuel is already molten. However, this simplistic argument belies the fact that MSR fuels pose unique safety issues. Not only is the hot liquid fuel highly corrosive, but it is also difficult to model its complex behavior as it flows through a reactor system. If cooling is interrupted, the fuel can heat up and destroy an MSR in a matter of minutes. Perhaps the most serious safety flaw is that, in contrast to solid-fueled reactors, MSRs routinely release large quantities of gaseous fission products, which must be trapped and stored. Some released gases quickly decay into troublesome radionuclides such as cesium-137— the highly radioactive isotope that caused persistent and extensive environmental contamination following the Chernobyl and Fukushima nuclear accidents.

Sustainability: A main argument for MSRs is that they are more flexible and can operate more sustainably than reactors using solid fuel. In theory, some MSRs would be able to use natural resources more efficiently than LWRs and generate lower amounts of long-lived nuclear waste. However, the actual sustainability improvements for a range of thermal and fast MSR designs are too small, even with optimistic performance assumptions, to justify their high safety and security risks.

Nuclear Proliferation/Terrorism: MSRs present unique challenges for nuclear security because it would be very difficult to account for nuclear material accurately as the liquid fuel flows through the reactor. In addition, some designs require on-site, continuously operating fuel reprocessing plants that could provide additional pathways for diverting or stealing nuclear-weapon-usable materials.

MSRs could also endanger global nuclear security by interfering with the worldwide network of radionuclide monitors put into place to verify compliance with the Comprehensive Nuclear Test Ban Treaty after it enters into force.5 MSRs release vast quantities of the same radioactive xenon isotopes that are signatures of clandestine nuclear explosions—an issue that MSR developers do not appear to have addressed. It is unclear whether it would be feasible or affordable to trap and store these isotopes at MSRs to the degree necessary to avoid degrading the effectiveness of the monitoring system to detect treaty violations.

Safely Commercializing NLWRs: Timelines and Costs

Can NLWRs be deployed quickly enough to play a significant role in reducing carbon emissions and avoiding the worst effects of climate change? The 2018 special report of the UN’s Intergovernmental Panel on Climate Change identified 85 energy supply pathways to 2050 capable of achieving the Paris Agreement target of limiting global mean temperature rise to 1.5°C. The median capacity of nuclear power in 2050 across those pathways is about 150 percent over the 2020 level. Taking into account planned retirements, this corresponds to the equivalent of at least two dozen 1,000 MWe reactors coming online globally each year between now and 2050— five times the recent global rate of new LWR construction. If the world must wait decades for NLWRs to be commercially available, they would have to be built even faster to fill the gap by 2050.

Some developers of NLWRs say that they will be able to meet this challenge by deploying their reactors commercially as soon as the late 2020s. However, such aggressive timelines are inconsistent with the recent experience of new reactors such as the Westinghouse AP1000, an evolutionary LWR. Although the AP1000 has some novel features, its designers leveraged many decades of LWR operating data. Even so, it took more than 30 years of research, development, and construction before the first AP1000—the Sanmen Unit 1 reactor in China—began to produce power in 2018.

How, then, could less-mature NLWR reactors be commercialized so much faster than the AP1000? At a minimum, commercial deployment in the 2020s would require bypassing two developmental stages that are critical for assuring safety and reliability: the demonstration of prototype reactors at reduced scale and at full scale. Prototype reactors are typically needed for demonstrating performance and conducting safety and fuel testing to address knowledge gaps in new reactor designs. Prototypes also may have additional safety features and instrumentation not included in the basic design, as well as limits on operation that would not apply to commercial units.

By a 2017 report, the DOE asserted that SFRs and HTGRs were mature enough for commercial demonstrations without the need for additional prototype testing. For either of these types, the DOE estimated it would cost approximately $4 billion and take 13 to 15 years to complete a first commercial demonstration unit, assuming that reactor construction and startup testing take seven years. After five years of operating the demonstration unit, additional commercial units could follow in the mid-2030s.

In contrast, for MSRs and other lower-maturity designs, the DOE report judged that both reduced-scale and full-scale prototypes (which the report referred to as “engineering” and “performance” demonstrations, respectively) would be needed before a commercial demonstration reactor could be built. These additional stages could add $2 billion to $4 billion to the cost and 20 years to the development timeline. The subsequent commercial demonstration would not begin until 2040; reactors would not be available for sale until the mid-2040s or even the 2050s.

In May 2020, after receiving $160 million in initial congressional funding for the new Advanced Reactor Demonstration Program (ARDP), the DOE issued a solicitation for two “advanced” commercial demonstration reactors. In October 2020, the DOE chose SFR and HTGR designs—as one might expect given its 2017 technology assessment. The DOE estimates that these projects will cost up to $3.2 billion each (with the vendors contributing 50 percent) for the reactors and their supporting fuel facilities. The department is requiring that the reactors be operational within seven years, a timeline—including NRC licensing, construction, fuel production, and startup testing—that it acknowledges is very aggressive.

However, even if this deadline can be met and the reactors work reliably, subsequent commercial units likely would not be ordered before the early 2030s. Moreover, it is far from certain that the two designs the DOE selected for the ARDP are mature enough for commercial demonstration. Past demonstrations of both SFRs and HTGRs have encountered safety and reliability problems. Additionally, for both reactor types, the DOE has chosen designs that differ significantly from past demonstration reactors.

In the 1990s, the NRC concluded that it would require information from representative prototype testing prior to licensing either of these reactor types—but no prototypes were ever built. More recently, in a letter to the NRC, the agency’s independent Advisory Committee on Reactor Safeguards reaffirmed the importance of prototypes in new reactor development. Nevertheless, the NRC—a far weaker regulator today—has apparently changed its position and may proceed with licensing the ARDP demonstration reactors without requiring prototype testing first. But by skipping prototype testing and proceeding directly to commercial units, these projects may run not only the risk of experincing unanticipated reliability problems, but also the risk of suffering serious accidents that could endanger public health and safety.

An additional challenge for NLWR demonstrations and subsequent commercial deployment is the availability of fuels for those reactors, which would differ significantly from the fuel that today’s LWRs use. Even a single small reactor could require a few tons of HALEU per year—far more than the 900 kilograms per year projected to be available over the next several years from a DOE-funded pilot enrichment plant that Centrus Energy Corporation is building in Piketon, Ohio. It is far from clear whether that pilot will succeed and can be scaled up in time to support the two NLWR demonstrations by 2027, not to mention the numerous other HALEU-fueled reactor projects that have been proposed……. https://ucsusa.org/resources/advanced-isnt-always-better#read-online-content

Tokyo’s ”Recovery Olympics”? But Japan has not recovered from the Fukushima nuclear meltdown

April 5, 2021

Japan Hasn’t Recovered 10 Years After Fukushima Meltdown, https://truthout.org/articles/japan-hasnt-recovered-10-years-after-fukushima-meltdown/,  Arnie Gundersen, -March 11, 2021  

On March 11, 2011, a devastating offshore earthquake and ensuing tsunami rocked Japan and resulted in nuclear meltdowns in three nuclear reactors at the Fukushima Daiichi nuclear site. Until the 2020 Tokyo Olympics were placed on a one-year hiatus because of concerns over COVID-19, the Japanese government had portrayed these events as the “Recovery Olympics.” It had hoped to use the Olympics to showcase a claimed restoration of Japan since it was devastated in 2011. But has Japan really “recovered?”Recently, corresponding author Marco Kaltofen (Worcester Polytechnic Institute), co-author Maggie Gundersen (Fairewinds Energy Education) and I published our second peer-reviewed journal article analyzing hundreds of radioactive samples from northern Japan that we collected with assistance from Japanese citizens and scientists. Our sampling on five occasions over almost a decade totaled 70 days on the ground. Here are four things we discovered.

1. Existing radiation maps ignore significant sources of radiological exposure.

Most of the radiation maps of northern Japan are based on external radiation detected in handheld instrument measurements by citizens and scientists, who then link the measurements to GPS coordinates while downloading that data into a massive database. This information about direct, external radiation is certainly important, but it has become the de facto criteria for decision makers in Japan to decide which cities and towns should be repopulated.

We found that this approach only provides limited policy alternatives and serves to minimize potential population exposure for two reasons. First, the Geiger counter data is for external radiation that was deposited on the ground external to human bodies and ignores radiation imbibed or inhaled as “hot particles” into the human body.

Secondly, the external radiation data frequently displayed for northern Japan is based on radiation emitted from only a single radioactive isotope, Cesium-137 (Cs-137), as measured externally. On the other hand, our papers show a wide variety of isotopes that are not detected by handheld Geiger counters or absorbed externally. We show that there is an extensive brew of various isotopes present in radioactive dust that is inhaled or imbibed. Our papers indicate that the radioactive concentration in these dust particles varies widely, by a factor of 1 million, with 5 percent (3 sigma) of these “hot particles” 10,000 times more radioactive than the mean. Our most radioactive dust particle was collected 300 miles from the site of the meltdown.

Furthermore, the data show that alpha, beta and gamma-emitting contaminants in radioactive fallout from the Daiichi meltdowns have not traveled together in lockstep. This means that measuring only beta-emitters like Cesium-137 or only total gamma (as you would with a Geiger counter) is not enough to map the full impact of the fallout. Alpha-emitters must also be measured to protect the public health. This is especially important because of the serious health impacts that can come from exposure to alpha radiation.

2. Northern Japan remains radiologically contaminated.

When a nuclear chain reaction stops, the hazardous remnants of the previously split uranium atoms, euphemistically called “fission products,” are left behind and remain radioactive for centuries. The triple meltdowns and explosions at Fukushima Daiichi Units 1, 2 and 3 in March 2011 released an enormous amount of these fission products into the environment. Wind currents pushed as much as 80 percent of this radiation over the Pacific Ocean, while 20 percent fell on northern Japan, forcing the evacuation of approximately 160,000 Japanese citizens from ancestral lands.

Absent any human intervention, short-lived fission products that originally accounted for more than half of this contamination have already decayed away during the last nine years, while even more has washed into the Pacific from storms and typhoons. Limited cleanup efforts by the Japanese government have further reduced the contamination in a fraction of the populated portion of the devastated Fukushima prefecture. Greater than 10 million tons of radioactive material have been collected and stored in 10 million individual large black bags at hundreds of locations. However, due to mountainous terrain, more than 70 percent of Fukushima prefecture will never be decontaminated.

Absent any human intervention, short-lived fission products that originally accounted for more than half of this contamination have already decayed away during the last nine years, while even more has washed into the Pacific from storms and typhoons. Limited cleanup efforts by the Japanese government have further reduced the contamination in a fraction of the populated portion of the devastated Fukushima prefecture. Greater than 10 million tons of radioactive material have been collected and stored in 10 million individual large black bags at hundreds of locations. However, due to mountainous terrain, more than 70 percent of Fukushima prefecture will never be decontaminated.

As the cost and effort to completely decontaminate the entire land mass of Fukushima prefecture would be prohibitive, the Japanese government has focused on cleaning only populated areas. It also increased the “allowable” radiation limit 20-fold, after an initial partial decontamination, from 1 milli-Sievert to 20 milli-Sieverts per year (100 millirem to 2 rem) to facilitate repopulation of abandoned villages. A 20-fold increase in radiation will create a 20-fold increase in radiation-induced cancers. A significant fraction of residents chose not to return, recognizing the increased risk that these higher approved limits present.

3. Previously “cleaned” areas are becoming radiologically contaminated yet again.

The city of Minamisoma was contaminated and evacuated at the height of the Fukushima disaster. After a period of several years, radiation in the city was remediated and citizens were allowed to return. Minamisoma City Hall was decontaminated, with a new epoxy roof applied after the meltdowns in 2011. The authors collected samples from this previously “clean” fourth-story roof in 2016 and again in 2017, finding high levels of alpha radiation in the relative absence of the normally ubiquitous Cesium isotopes. This can only imply that wind-borne contamination from uncleaned areas is recontaminating those areas determined habitable.

4. Olympic venues in Fukushima prefecture are more contaminated than in Tokyo Olympic venues.

Suburbs of Tokyo are approximately 120 miles from the reactors at Fukushima Daiichi. We found particulate radiation at Olympic venues in Tokyo to be normal compared to other cities worldwide. We found that areas in Japan beyond the Olympic venues were seven times more contaminated than the venues themselves. Contamination at the Olympic venues in Fukushima prefecture, planned to showcase the region’s recovery, were also more contaminated than the Tokyo venues. We found that on average, these northern Olympic venues were two to three times more contaminated with “hot particles” than venues in Tokyo.

We also detected small but statistically significant levels of plutonium at the J-Village national soccer camp in Fukushima prefecture. Even though the Japanese government claims to have thoroughly decontaminated these Fukushima locations, it is not surprising that these Olympic venues remain contaminated. As discussed previously, since the entirety of the prefecture’s area will never be decontaminated, these areas will continue to have wind-borne contamination for centuries.

Science on a Shoestring

As Fukushima was melting down, nuclear advocates in the U.S. were testifying to the Washington State legislature, saying that Japan’s nuclear plants would not be a problem, and that working in a nuclear plant is “safer than working in Toys R Us.” Not surprisingly, those same zealots are now claiming that there will be no increase in cancer fatalities as a result of the three Fukushima meltdowns. However, not including the hot particle contamination my colleagues and I have identified, the UN estimates that thousands of fatalities will occur. Others, including myself, believe the actual cancer increase could result in upwards of 100,000 increased deaths as a result of the radioactive microparticles strewn into the environment.

There is no doubt that radiological conditions in Japan have improved in the decade since the triple meltdowns at Fukushima Daiichi. However, our data show that Japan has not “recovered,” nor can it ever return to pre-meltdown norms. Public relations campaigns by interested parties cannot obscure the recontamination of populated areas in northern Japan that will continue to occur.

Hasegawa, the former head of Maeda Ward in Fukushima prefecture at the time of the Fukushima disaster, sums up the sentiment of most of Japanese citizens in northern Japan: “The nuclear plant took everything.… We are just in the way of the Olympics. In the end, the radiation-affected places like us are just in the way. They are going ahead just wanting to get rid of these places from Japan, to forget.”

There is an old laboratory adage that says, “The best way to clean up a spill is not to have a spill,” and this applies on a much larger scale to the entirety of northern Japan, where cleanup will remain economically unfeasible. Our future plans to further support our hypothesis that Japan remains contaminated will involve testing the shoestrings of Olympic athletes and visitors to northern Japan. Shoestrings are useful, as their woven fabric traps dust which may assist in determining the extent of contamination into populated areas in northern Japan compared to that in Tokyo.

Japan’s Nuclear Clean-Up Has No End in Sight

April 5, 2021

Climbing Without a Map: Japan’s Nuclear Clean-Up Has No End in Sight, U.S. News, By Reuters, Wire Service Content March 12, 2021,   BY SAKURA MURAKAMI AND Aaron Sheldrick TOKYO (Reuters) – For one minute this week, workers at the Fukushima nuclear station fell silent to mark the 10-year anniversary of a natural disaster that triggered the worst nuclear accident since Chernobyl.

Then they went back to work tearing down the reactors melted down in the days after a tsunami on March 11, 2011.

The job ranks as the most expensive and dangerous nuclear clean-up ever attempted. A decade in, an army of engineers, scientists and 5,000 workers are still mapping out a project many expect will not be completed in their lifetime.

Naoaki Okuzumi, the head of research at Japan’s lead research institute on decommissioning, compares the work ahead to climbing a mountain range – without a map.

“The feeling we have is, you think the summit’s right there, but then you reach it and can see another summit, further beyond,” Okuzumi told Reuters.

Okuzumi and others need to find a way to remove and safely store 880 tonnes of highly radioactive uranium fuel along with a larger mass of concrete and metal into which fuel melted a decade ago during the accident.

The robotic tools to do the job don’t yet exist. There is no plan for where to put the radioactive material when it is removed.

Japan’s government says the job could run 40 years. Outside experts say it could take twice as long, pushing completion near the close of the century……..

It wasn’t until 2017 that engineers understood how complicated the clean-up would become. By that point, five specially designed robots had been dispatched through the dark, contaminated waters pumped in to cool the uranium. But radiation zapped their electronics.

One robot developed by Toshiba Corp, nicknamed the “little sunfish”, a device about the size of a loaf of bread, provided an early glimpse of the chaotic damage around the cores.

Kenji Matsuzaki, a robot technician at Toshiba who led development of the “sunfish”, had assumed that they would find melted fuel at the bottom of the reactors.

But the sunfish’s first video images showed a tumult of destruction, with overturned structures inside the reactor, clumps of unrecognizable brown debris and dangerously radioactive metal.

“I expected it to be broken, but I didn’t expect it would be this bad,” Matsuzaki said.

The delivery of a robotic arm to start removing fuel, developed in a $16 million programme with the UK’s Nuclear Decommissioning Authority, has been delayed until 2022. Tepco plans to use it to grab some debris from inside reactor 2 for testing and to help plan the main operation………….

But the cleanup has been delayed by the buildup of contaminated water in tanks that crowd the site. The melted cores are kept cool by pumping water into damaged reactor vessels.

But the cleanup has been delayed by the buildup of contaminated water in tanks that crowd the site. The melted cores are kept cool by pumping water into damaged reactor vessels.  https://www.usnews.com/news/world/articles/2021-03-12/climbing-without-a-map-japans-nuclear-clean-up-has-no-end-in-sight