Small nuclear reactors may create 30 times more radioactive waste

“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), in a press release. "These findings stand in sharp contrast to the cost and waste reduction benefits that advocates have claimed for advanced nuclear technologies.”

The future of nuclear energy?

Small modular reactors, which generate less than 300 megawatts of electric power, do sound like the perfect package as their smaller size means they can be prefabricated in factories and shipped for installation, which makes them cheaper and easier to build than the nuclear power plants we have today.

According to some industry analysts, SMRs may create fewer radioactive wastes than large-scale reactors. However, the new study paints a completely different picture.

A team of researchers from Stanford University and the University of British Columbia analyzed the nuclear waste streams from three different types of small modular reactors by Toshiba, NuScale, and Terrestrial Energy that are currently in development according to the press release.

Due to their smaller size, the study discovered that small modular reactors would face higher neutron leakage than regular reactors, which affects the amount and composition of their waste streams.

"The more neutrons that are leaked, the greater the amount of radioactivity created by the activation process of neutrons," study co-author Rodney Ewing, the Frank Stanton Professor in Nuclear Security at Stanford and co-director of CISAC, said. "We found that small modular reactors will generate at least nine times more neutron-activated steel than conventional power plants. These radioactive materials have to be carefully managed prior to disposal, which will be expensive."

Moreover, spent nuclear fuel from small modular reactors will be discharged in greater volumes per unit of energy extracted. They can also be significantly more complex than the spent fuel discharged from conventional power plants, according to the new analysis.

"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."

Exacerbating the problems associated with nuclear waste

In conclusion, the researchers stated that small modular designs are inferior to conventional reactors in terms of radioactive waste generations, management needs, and disposal alternatives.

“The takeaway message for the industry and investors is that the back end of the fuel cycle may include hidden costs that must be addressed,” Macfarlane added. "It’s in the best interest of the reactor designer and the regulator to understand the waste implications of these reactors."

Today, commercial nuclear power reactors in the United States alone have produced around 88,000 metric tons of spent nuclear fuel, the press release states. Spent nuclear fuel is currently kept at reactor sites in pools or in dry casks, accumulating at a pace of roughly 2,000 metric tonnes per year, which further highlights the significance of rigorous research prior to the introduction of novel technologies.