US regulators set the stage for small, local nuclear power stations

What could go wrong? Study finds waste is more reactive, making it more dangerous

The US Nuclear Regulatory Commission is set to approve the country's first ever small modular reactor (SMR) design, setting up a potential expansion of small-scale nuclear power stations across the country. 

The certification [PDF] was given to NuScale for its SMRs: 76-foot tall, 15-foot wide (23m x 4.6m) pressurized-water reactors that can operate in groups of four, six or 12, and use passive processes to heat water and move it through the reactor's stages. 

Each NuScale SMR produces 50 MW of power, and they're able to be assembled at a NuScale facility before being shipped to their final destination. Once on site, the reactors are installed below ground level in a pool that serves as their primary heat sink.

"NRC certification means the design meets the agency's applicable safety requirements," the NRC said.

Applications for new nuclear power plants that reference certified designs, like the NuScale SMR, are exempt from having to address project issues resolved by the approved design, the NRC added. 

NuScale's SMR is only the seventh reactor design to be certified for use in the US, the commission said.

That reactor design was initially submitted to the NRC in 2016, and received a preliminary safety approval in 2020 [PDF]. In the 2020 notice, the NRC mentioned NuScale was working on a 60 MW version of its SMR, but that isn't mentioned in the final approval notice posted last week. 

The NRC's final approval notice also doesn't make any mention of NuScale's 4- or 6-reactor setups, though the standard design approval issued in 2020 does mention it green lighted "NuScale plant[s] consisting of up to 12 nuclear power modules, with each module having an output of 50 MWe."

NuScale's SMR commercialization thumbs-up will be active 30 days after the NRC publishes it in the Federal Register. There's not a formal date for that yet, as the commission's notice only said it has "directed staff to issue a final rule," not that the decision has been written yet.

SMRs in your neighborhood soon?

Late last year when it said it was approaching commercialization, NuScale gave a name to its SMR power plants: VOYGR. The company is working on several US-based projects, with the first VOYGR plant slated for completion in 2029 at the US Department of Energy's Idaho National Laboratory.

Dubbed the Carbon Free Power Project (CFPP), the new facility will be located near Idaho Falls and will use six of NuScale's SMRs. On the CFPP's website, it said that the plant will deploy six modules able to deliver 77 MW of power – more than the 50 MW NuScale's reactors are currently able to produce. 

But concerns remain over SMR's feasibility, typically regarding how much waste they produce. A study released in June found that SMRs produce 35x more waste than their larger predecessors, with much of it in long-lived equivalent waste and low and intermediate-level waste (LILW). 

The study also found that the waste generated by SMRs is more reactive, making it more dangerous, and it may be the very nature of their design that makes them less safe. Reactive fuels and coolants are needed to catch stray neutrons that would normally be stopped by the walls of larger reactors, and those fuels and coolants become hazardous waste as well.

NuScale told us in June that it disagreed with the conclusions from that study, but didn't answer as to whether its SMRs generate more LILW. ®