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US moves closer to approving first advanced nuclear reactor
02 July 2021Jeff Beattie
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.