By JB

Stanford-led research finds small modular reactors will exacerbate challenges of highly radioactive nuclear waste

Small modular reactors, long touted as the future of nuclear energy, will actually generate more radioactive waste than conventional nuclear power plants, according to research from Stanford and the University of British Columbia.

A study published in May 31 2022 in Proceedings of the National Academy of Sciences has reached the conclusion.

“Our results show that most small modular reactor designs will actually increase the volume of nuclear waste in need of management and disposal, by factors of 2 to 30 for the reactors in our case study,” said study lead author Lindsay Krall, a former MacArthur Postdoctoral Fellow at Stanford University’s Center for International Security and Cooperation (CISAC). “These findings stand in sharp contrast to the cost and waste reduction benefits that advocates have claimed for advanced nuclear technologies.”

“Simple metrics, such as estimates of the mass of spent fuel, offer little insight into the resources that will be required to store, package, and dispose of the spent fuel and other radioactive waste,” said Krall, who is now a scientist at the Swedish Nuclear Fuel and Waste Management Company. “In fact, remarkably few studies have analyzed the management and disposal of nuclear waste streams from small modular reactors.”

The study found that “The excess volume of SMR wastes will bear chemical and physical differences from PWR waste that will impact their management and final disposal. 

Note: A pressurized water reactor (PWR) is a type of nuclear reactor that uses water as both the coolant and the moderator, and it’s the most common type of nuclear reactor used in power plants globally. 

“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.”

“Some small modular reactor designs call for chemically exotic fuels and coolants that can produce difficult-to-manage wastes for disposal,” said co-author Allison Macfarlane, professor and director of the School of Public Policy and Global Affairs at the University of British Columbia. “Those exotic fuels and coolants may require costly chemical treatment prior to disposal.”

The research team estimated that after “10,000 years, the radiotoxicity of plutonium in spent fuels discharged from the three study modules would be at least 50 percent higher than the plutonium in conventional spent fuel per unit energy extracted.”

If that isn’t bad enough, in the shorter term they then worryingly go on to

Neutron Leakage

“The probability of neutron leakage is a function of the reactor dimensions and the neutron diffusion length, the latter of which is determined by the neutron scattering properties of the fuel, coolant, moderator, and structural materials in the reactor core. The neutron diffusion length will be the same in reactors that use similar fuel cycles and fuel–coolant–moderator combinations; thus, the neutron leakage probability will be larger for an SMR than for a larger reactor of a similar type.”

Nuclear waste from small modular reactors | PNAS

Neutron leakage from nuclear reactors are harmful due to the penetrating nature of neutrons and their ability to cause significant cellular damage. Neutrons, unlike other types of radiation like gamma rays, can induce complex DNA damage.

Penetrating Nature:

Neutrons are uncharged particles that can travel long distances and penetrate deeply into tissues, leading to whole-body irradiation. 

Cellular Damage:
Neutrons can interact with atoms within cells, causing damage like cell death or changes in functionality, which can accumulate over time. 

High RBE:
Neutrons are considered a high-LET (linear energy transfer) radiation, meaning they deposit a significant amount of energy per unit distance, leading to more complex and potentially harder-to-repair DNA damage compared to low-LET radiation like gamma rays. 

Increased Cancer Risk:
Exposure to neutrons has been linked to an increased risk of cancer, particularly in the soft tissues of the body. 

Conclusion:

With Scotland’s abundance of natural energy resources

What is the bloody benefit of Small Nuclear Reactors?

JB