Preface. With climate change getting all the press and the coming energy crisis virtually no coverage, pro-nuclear forces are strongly pushing new nuclear plants as a way to lower CO2 emissions and deliver reliable power (but only baseload, they can’t balance wind and solar, only natural gas and hydroelectric do that, batteries don’t scale, too small to count). But since transportation can’t be electrified, as shown in “When Trucks Stop Running: Energy and the Future of Transportation”, or manufacturing, fertilizer, the half million products made with petroleum and other showstoppers shown in “Life After Fossil Fuels: A Reality Check on Alternative Energy“, why would we poison the world with nuclear wastes for a million years? With peak oil in 2018, and nuclear, wind, solar and other electricity generating contraptions utterly dependent on fossil fuels for their construction, it’s time to bury nuclear wastes since future generations won’t have the energy or technology.
SMR / GEN IV plants would make nuclear proliferation an even bigger issue.
I’ve extracted bits of two papers below, but they are worth reading in full.
The summary of the Union of Concerned Scientists 148 page report here skims the surface of the many issues with advanced nuclear reactors.
Alice Friedemann www.energyskeptic.com Author of Life After Fossil Fuels: A Reality Check on Alternative Energy; When Trucks Stop Running: Energy and the Future of Transportation”, Barriers to Making Algal Biofuels, & “Crunch! Whole Grain Artisan Chips and Crackers”. Women in ecology Podcasts: WGBH, Planet: Critical, Crazy Town, Collapse Chronicles, Derrick Jensen, Practical Prepping, Kunstler 253 &278, Peak Prosperity, Index of best energyskeptic posts
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Krall LM et al (2022) Nuclear waste from small modular reactors. PNAS. https://doi.org/10.1073/pnas.2111833119
Small modular reactors (SMRs), proposed as the future of nuclear energy, have purported cost and safety advantages over existing gigawatt-scale light water reactors (LWRs). However, remarkably few studies have assessed the implications of SMRs for the back end of the nuclear fuel cycle. The low-, intermediate-, and high-level waste stream characterization presented here reveals that SMRs will produce more voluminous and chemically/physically reactive waste than LWRs, which will impact options for the management and disposal of this waste. Results reveal that water-, molten salt–, and sodium-cooled SMR designs will increase the volume of nuclear waste in need of management and disposal by factors of 2 to 30.
Volume is not the most important evaluation metric; rather, geologic repository performance is driven by the decay heat power and the (radio-)chemistry of spent nuclear fuel, for which SMRs provide no benefit. SMRs will not reduce the generation of geochemically mobile 129I, 99Tc, and 79Se fission products, which are important dose contributors for most repository designs. In addition, SMR spent fuel will contain relatively high concentrations of fissile nuclides, which will demand novel approaches to evaluating criticality during storage and disposal. Since waste stream properties are influenced by neutron leakage, a basic physical process that is enhanced in small reactor cores, SMRs will exacerbate the challenges of nuclear waste management and disposal.
In the case of sodium- and molten salt–cooled SMRs, the primary coolant will be chemically reactive (section 3.4.3), heated to temperatures >500 °C, and highly radioactive (2). Under these extreme conditions, reactor components can have a shorter lifetime than the standard PWR (60 y), and this will increase decommissioning LILW volumes. In addition, non-light water SMRs will introduce uncommon types of LILW in the form of neutron reflectors and chemically reactive coolant or moderator materials.
Sodium coolant can burn when exposed to air or water, and the Bill gates touted Natrium sodium-cooled fast reactor could experience uncontrollable power increases that could lead to rapid core melting. And although this reactor was to be up and running by 2027, now delayed until 2028, the Union of Concerned Scientists says that if federal regulators require necessary safety demonstrations it could take at least 20 years and billions of dollars in additional costs to commercialize these reactors. This report also find that Natrium reactors would likely be less uranium-efficient, not good when Peak Uranium looms (Negin 2021).
Molten salt reactor vessel lifetimes will be limited by the corrosive, high-temperature, and radioactive in-core environment. In particular, the chromium content of 316-type stainless steel that constitutes a PWR pressure vessel is susceptible to corrosion in halide salts (25). Nevertheless, some developers, such as ThorCon, plan to adopt this stainless steel rather than to qualify a more corrosion-resistant material for the reactor vessel.
Since SMRs will generate >10-fold more neutron-activated steel than the energy-equivalent LWR and will introduce the need to chemically treat radioactive sodium and molten salt coolants, they may significantly increase the costs and exposure risks associated with nuclear decommissioning.
Conclusion: This analysis of three distinct SMR designs shows that, relative to a gigawatt-scale PWR, these reactors will increase the energy-equivalent volumes of SNF, long-lived LILW, and short-lived LILW by factors of up to 5.5, 30, and 35, respectively. These findings stand in contrast to the waste reduction benefits that advocates have claimed for advanced nuclear technologies. More importantly, SMR waste streams will bear significant (radio-)chemical differences from those of existing reactors. Molten salt– and sodium-cooled SMRs will use highly corrosive and pyrophoric fuels and coolants that, following irradiation, will become highly radioactive. Relatively high concentrations of 239Pu and 235U in low–burnup SMR SNF will render recriticality a significant risk for these chemically unstable waste streams.
SMR waste streams that are susceptible to exothermic chemical reactions or nuclear criticality when in contact with water or other repository materials are unsuitable for direct geologic disposal. Hence, the large volumes of reactive SMR waste will need to be treated, conditioned, and appropriately packaged prior to geological disposal. These processes will introduce significant costs—and likely, radiation exposure and fissile material proliferation pathways—to the back end of the nuclear fuel cycle and entail no apparent benefit for long-term safety.
Given that SMRs are incompatible with existing nuclear waste disposal technologies and concepts, future studies should address whether safe interim storage of reactive SMR waste streams is credible in the context of a continued delay in the development of a geologic repository in the United States.
Gardner T (2021) Advanced nuclear reactors no safer than conventional nuclear plants, says science group. Reuters.
A new generation of so-called “advanced” nuclear power reactors that Washington believes could help fight climate change often present greater proliferation risks than conventional nuclear power, a science advocacy group said on Thursday.
President Joe Biden, a Democrat, has made curbing climate change a priority and has supported research and development for advanced nuclear technologies.
The reactors are also popular with many Republicans. Last October, the month before Biden was elected, the U.S. Department of Energy, awarded $80 million each to TerraPower LLC and X-energy to build reactors it said would be operational in seven years.
Advanced reactors are generally far smaller than conventional reactors and are cooled with materials such as molten salt instead of with water. Backers say they are safer and some can use nuclear waste as fuel.
“The technologies are certainly different from current reactors, but it is not at all clear they are better,” said Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists. “In many cases, they are worse with regard to … safety, and the potential for severe accidents and potential nuclear proliferation.”
Nuclear reactors generate virtually emissions-free power which means conventional ones, at least, will play a role in efforts to decarbonize the economy by 2050, a goal of the Biden administration. But several of the 94 U.S. conventional nuclear plants are shutting due to high safety costs and competition from natural gas and wind and solar energy.
That has helped spark initial funding for a new generation of reactors. But fuel for many of those reactors would have to be enriched at a much higher rate than conventional fuel, meaning the fuel supply chain could be an attractive target for militants looking to create a crude nuclear weapon.
Also, nuclear waste from today’s reactors would have to be reprocessed to make fuel. That technique has not been practiced in the United States for decades because of proliferation and cost concerns. Other advanced reactors emit large amounts of radioactive gases, a potentially problematic waste stream.
Lyman said advanced nuclear development funds would be better spent on bolstering conventional nuclear plants from the risks of earthquakes and climate change, such as flooding. The report recommended that the Department of Energy suspend its advanced reactor demonstration program until the Nuclear Regulatory Commission (NRC) requires prototype testing before reactors can be licensed for commercial use.
References
Kramer D (2017) DOE’s advanced nuclear reactor program deemed ineffective. According to a new review, the Office of Nuclear Energy has shifted its priorities too often and overspent on facility upkeep. Physics Today.
Negin E (2021) Next-Gen nuclear reactor hype. There is little evidence fanciful new designs will be cheaper or safer. Scientific American.