The NuScale small modular reactor project has received good news and bad in recent days, and the path ahead remains unclear.
First the good news. The U.S. Nuclear Regulatory Commission August 28 approved the “final safety evaluation report” for the 50-MW reactor design by Portland, Ore.-based NuScale Power LLC. In a press release, the NRC said, “This meets the agency’s original 42-month technical review schedule and demonstrates the NRC’s commitment to timely licensing of safe technologies for new, advanced reactors. The NRC is preparing a rulemaking to certify the design.”
The design approval is not a license to build the project. NuScale must come back to the NRC for a combined construction and operating license (COL) before its project on federal land in Idaho’s National Laboratory site can go forward. The major investor in NuScale is Fluor Corp., a major power plant construction company.
The project aims at building 12 of its units at a total price tag of $6 billion, selling the power to the Utah Associated Municipal Power Systems (UAMPS), a joint action public power agency with 47 members in Utah, California, Idaho, Nevada, New Mexico, and Wyoming.
If all goes according to the current schedule (and nuclear projects rarely go according to schedule), the first module of the SMR will be in operation in 2029, with the remaining modules in service in 2030. That’s already three years later than the original estimates.
Now the bad news. Some of the UAMPS members who initially committed to buying power from the project are having doubts. The city of Logan, Utah’s city council has voted to exit the SMR project, citing increased costs to the city for the power. The Utah Taxpayers Association has called for the Utah cities to “reconsider” their participation, because of the uncertain costs.
Soon after, the city of Lehi, Utah, voted to back out of the SMR project, citing escalating power costs.
Then there are is a technical issue about the passively-cooled small reactor that could sidetrack the project. What’s in the air is what happens to the boron in the cooling water in the case of the reactor overheating. The NuScale reactor uses a design where steam from overheating would flow to a pool of water below the reactor, which would then condense the steam and relieve the pressure.
But several NRC scientists are troubled that the design would leave the neutron-absorbing boron trapped in the reactor. When the condensed water returned to cool the reactor, there would not be an ability to slow the neutrons and the plant could “go critical,” or experience a potential meltdown.
In a press conference Sept. 2, Edwin Lyman of the Union of Concerned Scientists called attention to a dissent to the NRC staff recommendation of approval of the FSER by NRC scientist Dr. Shanlai Lu, a senior nuclear engineer in the Office of Nuclear Reactor Regulation. Lu wrote in a dissent that the reactor “could reach fuel failure and prompt criticality condition for a wide range of initial conditions. … Based on event analysis and the identified modeling deficiencies, the author believes that the NuScale reactor will most likely experience core damage.”
It’s a concern that has been circulating in the NRC for months. In late July, the NRC’s Advisory Committee on Reactor Safeguards highlighted the boron issue. ACRS Chairman Matthew Sunseri wrote Margaret Doane, the NRC executive director for operations, “Operator recovery actions raise the possibility of an influx of deborated water into the core, which may result in recriticality, return to power, and the potential for core damage.” Sunseri said NuScale “should have a stronger technical basis than is currently documented that demonstrates a path to successful recovery to prevent core damage. The probabilistic risk assessment (PRA) should be updated accordingly at the COL stage to appropriately reflect the risk of boron dilution events, including associated operator actions.”
— Kennedy Maize