US moves closer to approving first advanced nuclear reactor

In what would be the first advanced reactor approval for the US nuclear industry, the Nuclear Regulatory Commission (NRC) is propos­ing to certify NuScale Power's 77-MW small modular reactor (SMR) design as safe for domestic commercial use.

The NRC, in a 1 July Federal Register notice, cited a previously granted assessment that found "no significant environmental impact" from certifying NuScale's reactor as well as the agency's positive safety evalua­tion of the technology from August 2020.

The agency's proposed rule is giant step forward for NuScale, leav­ing only a final regulatory hurdle—final NRC approval—before it becomes the first US SMR vendor able to take its reactor to market.

Comments can be submitted through 30 August on the proposal.

As further indication of the market's optimism about NuScale, the company announced on 30 June that it has finalized an investment agreement with GS Energy North America Investments, the US entity of the South Korean leading energy services provider. As part of a long-term strategic relationship established under the agreement, GS Energy will provide a cash investment in NuScale Power and support deployment of NuScale plants.

"GS Energy's renowned expertise in energy project development complements our effort to demonstrate how cleaner and safer advanced nuclear technology can bring numerous economic and environmental benefits, especially as the global community transitions to reliable, clean energy," said John Hopkins, NuScale Power chairman and CEO.

Around the world, nuclear power is enjoying renewed attention from a range of parties that includes the Russian government, the International Energy Agency, and Bill Gates, who has invested about $2 billion in TerraPower, another US-based nuclear plant developer.

Not only does nuclear power provide about 20% of electricity in the United States today, but the Fuel Cell and Hydrogen Energy Association said its role in a net-zero economy could increase because it can deliver 24/7 carbon-free power to produce green hydrogen. That hydrogen would, in turn, power fuel cells.

"Fuel cells generate electricity with virtually zero air pollutants, and rapid scale-up of hydrogen production could reduce the nation's carbon emissions by 16% by 2050. By 2050, greater fuel cell deployment could also reduce carbon emissions in the U.S. transportation sector by 30% and lower NOx emissions by 36%," the association said.

The US association signed a memorandum of understanding with its South Korea counterpart, the Hydrogen Convergence Alliance, last year to share information and develop codes and standards.

NRC's review

For NuScale's design, the NRC is proposing to amend the commission's regulations related to control room staffing to accommodate NuScale's comparatively small reactor, which is meant to be installed with multiple units at a single site. Because NRC's current regulations were developed for the much larger reactors in operation today, they do not contemplate one control room running more than one reactor, as is the case with NuScale's modular design.

To solve that problem, the proposed rule contains "alternative staffing requirement provisions" that would accommodate NuS­cale's planned plant layout.

However, the Federal Register notice also makes clear that those seeking a license from the agency to build and operate NuScale's SMR will have to resolve three important technical issues that have safety implications.

This type of stipulation is not unheard-of for nuclear power. Westinghouse's AP1000 reactor, which was certified in 2011 and is under construction in Georgia currently, was approved by NRC with certain open items that were resolved by specific project developers.

In the NuScale case, the agency said it found "insufficient design details available regarding … the presence of large penetrations, such as the main steam lines; main feedwater lines; and power module bay heating, ventilation, and air conditioning lines in the radiation shield wall between the power module bay and the reactor build­ing steam gallery area."

Without that information, NRC said it "is unable to confirm that the radiological doses to work­ers will be maintained within the radiation zone limits specified in the application."

But the agency said the question can be addressed in construction license applica­tions because it involves a localized area of the plant without affecting other aspects of NRC's design certification review.

NRC said the same was true of questions about potential leakage from the NuScale reactor's combustible gas monitoring system and the potential for leakage from this system outside the reactor's containment structure.

The agency also had questions about the potential for "density wave oscillations" in the reactor's steam generator. The agency said those oscillations can affect the "struc­tural and leakage integrity" of the steam generators, particularly components called inlet flow restrictors.

Solving those problems could fall to Utah Associated Municipal Power Systems (UAMPS), a public power provider now on track to be the first to deploy NuScale's design. UAMPS has said it hopes to build six SMRs at the Energy Department's Idaho National Laboratory with significant financial assistance from the federal government.

NuScale's technology

Oregon-based NuScale is in an expanding race by several companies to develop and sell a wide variety of advanced reactors, which are generally designed to have cost, dual-use, and safety advantages over the cur­rent fleet, which is having trouble competing financially with renewable power and plants burning inexpensive shale gas.

NuScale's reactor, for example, is to be built underground, reducing security concerns and costs. The company says that in the event of an accident, its reactor will safely shut down and self-cool with no opera­tor action, power or additional cooling water needed, eliminating any chance of fuel melt.

One reason that NuScale's design has advanced quickly is that it is essentially a scaled-down version of the pressurized water reactor technology in use in the majority of operating US reactors today. That design similarity has helped speed the NRC review, compared to more radical SMR designs now under development that use dif­ferent kinds of fuel and safety technologies.

Other vendors are preparing to seek NRC certification for reactor technologies not cur­rently in commercial operation, including "fast-neutron," pebble bed, molten salt, and micro-reactors. At least 20 such companies in North America are working on advanced designs, and several have begun interacting with NRC.

NRC says it is in "pre-application" talks or anticipates such talks with General Atomics about a 265-MW helium-cooled fast reactor design; X-energy about its 80 MW high-tem­perature, gas cooled reactor; TerraPower and GE Hitachi about their Natrium reactor, a 345- MW design that is paired with energy storage; Kairos Power about its 140-MW molten-salt reactor; TerraPower about its molten chloride fast reactor; Westinghouse about its eVinci micro reactor; and Terrestrial Energy about its 190-MW Integral Molten Salt Reactor.

Original reporting by:

Jeff Beattie, "The Energy Daily,"https://www.theenergydaily.com/ted/,

Kevin Adler, Net Zero Business Daily.