Utah Associated Municipal Power Systems (UAMPS) said on 19 July that it would reduce the number of small modular reactors (SMRs) it planned to build in Idaho from 12 to six. The project is part of a US Department of Energy (DOE) initiative to reduce greenhouse gas emissions by using nuclear power to complement intermittent renewable energy. DOE in late 2020 awarded the cooperative about $1.4 billion to support development and construction of the commercial reactors at its site in eastern Idaho that includes the Idaho National Laboratory.

The reactors are being built by Oregon-based NuScale Power. The US Nuclear Regulatory Commission (NRC) last year approved NuScale's application for the SMRs, the first design approval for a small commercial nuclear reactor. On 1 July, NRC issued a proposed rule for NuScale design certification and requested comments from the public on the reactor’s design control document and environmental assessment. Comments are being accepted through August 30.

"Before joining a next-generation, first-of-a-kind nuclear plant, utilities obviously want to be certain the plant is feasible and will be built," said UAMPS spokesman LaVarr Webb. "Now that we have made significant progress, including a large cost-share award from the Department of Energy, and NuScale has received design approval, we're seeing more and more utilities express interest in the plant."

UAMPS said the reactors will be more efficient than previously planned following a redesign by NuScale and so the amount of power produced will only fall from 600 to 462MWe. Webb said a plant with six reactors would be the right size for its members and outside utilities that want to join. Idaho Falls has committed to buying 5MWe from the reactors through the Carbon Free Power Project (CFPP). The city had been committed to 10MWe but reduced the amount in October amid concerns about financial risks.

UAMPS announced its plan to develop the CFPP using NuScale SMRs in 2015. At that time it planned 12 50MWe modules for a plant that could produce a total of 600 MWe. This increased to 720MWe, when UAMPS opted to scale up to 60MWe modules. Subsequently UAMPS participants chose to build 77MWe modules but downsize the plant from 12 units to six, which would yield 462 MWe.

The CFPP had 33 participants in the project in October 2020 when DOE funding was announced but the number has since fallen to 28, although Webb is optimistic more participants may still join.

According to a 16 July article in Idaho’s Post Register, the 28 participants have committed to a total of 103MWe, and the energy cost that project partners expect to pay following the switch to six 77MWe modules has risen from $55/MWh to $58/MWh. 

UAMPS plans to submit the combined license application (COLA) to the NRC in 2024. “The project is in great shape and is on schedule,” Webb said. “We are entering the next phase of COLA preparation, which is a big step forward. Construction start will depend more on how long the COLA review takes, but the change from 12 modules to six is not expected to delay the overall schedule. The first module is still scheduled to be operational in 2029, and the full plant in 2030.”

On July 1 of this year, the NRC issued a proposed rule for NuScale design certification and requested comments from the public on the reactor’s design control document and environmental assessment. Comments are being accepted through August 30.