Adam Vaughan is a writer.
An artist's impression of a power plant.
Oregon State University has NuScale Power.
When generating the same amount of power, mini nuclear power stations may produce more radioactive waste than traditional ones.
Small modular reactor (SMRs) have been proposed as a cheaper and faster way to build new nuclear power capacity, with UK prime minister Boris Johnson claiming they could be generating electricity by 2030. NuScale Power received financial support from the US government to develop its version of the technology.
There has been no independent assessment of how radioactive waste produced by SMRs would compare with waste produced by large-scale peers.
Lindsay Krall and her colleagues used data from NuScale Power to model the waste from three different SMR technologies.
They found that SMRs could increase the volume of short-lived low and intermediate level waste by up to 35 times compared to a large conventional reactor. The expected variation in the SMR designs are reflected in the figures.
The information being put out by reactor developers can be seen as promotional.
The study suggests that SMRs produce higher volumes and greater complexity of waste because they are naturally less efficient. Nuclear power generation involves a nuclear chain reaction, in which one single nuclear reaction in the reactor core creates neutrons that then go on to cause an average of one or more subsequent nuclear reactions. However, according to Krall’s team, SMRs leak more neutrons out of their core than a larger reactor, meaning they cannot maintain the self-sustaining reaction for as long. Even a small difference in neutron leakage results in a substantial impact on the composition of the waste, says Krall.
Diane Hughes at NuScale Power disagrees with the conclusion that the NuScale design creates more used spent fuel per unit of energy.
The UK government gave funding for Rolls-Royce to make its own version of the technology. This design was not considered in the new study, but a company spokesman said Rolls-Royce SMR would be submitting estimates on waste volumes as part of its years-long journey through the UK's nuclear regulatory approval process. The Rolls-Royce SMR design includes some technical innovations that reduce waste.
Only two countries have made progress on their plans to store their nuclear waste underground.
There is a journal reference in the PNAS.
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