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Nuclear Notes — Thursday, Jan. 26, 2023

Matthew Wald

A Regulatory Rush Job that will be a Disaster for Advanced Nuclear

In 2019, Congress told the Nuclear Regulatory Commission to modernize its regulations and produce a simpler, technologically neutral pathway for licensing advanced reactors. The advanced reactors, which are smaller and safer than their forbearers, are fundamentally different machines that use different coolants and fuel forms than the current generation of reactors. That means using existing regulations to license them makes little sense.

Unfortunately, three years later, the NRC staff has unveiled a proposed rule that is even more burdensome and complicated than either of the two existing frameworks for licensing conventional nuclear reactors, clocking in at 1,200 pages—twice as long as either existing rule.

The proposed rule would impose useless burdens on new reactors, stunting their progress. Some reactor developers say the new system, as drafted, is so bad that they might seek a license under the old, inappropriate system.

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A New Test Facility for Advanced Reactors, But It’s In Russia

The current Department Energy budget has provided no money for a fast neutron test reactor. But Russia’s Rosatom reported last week that it is racing ahead by placing a vessel for “the world’s largest multipurpose fast neutron research reactor,” in Dmitrovgrad.

Test reactors are important for assessing the durability of new hardware before it goes into reactor cores. The U.S. Department of Energy had drawn up plans for a Versatile Test Reactor, which could produce a flow of neutrons at the speeds and quantities expected in a variety of new reactor types. Reactor developers want the test reactor so they can immerse samples, mostly structural and fuel components into it to see how they would interact with neutrons over several years. Samples can be “aged” on an accelerated basis by increasing the density of the neutron flow.

“Fast” neutrons are neutrons that are emitted by fissioning uranium or plutonium, and not slowed down (or “moderated”) by water or graphite. With much higher energies, they can use more kinds of materials as fuel, including hard-to-dispose-of elements that are created in reactors and are currently treated as waste.

But so far, Congress has been skeptical, and has not funded construction.

Before the Russian invasion of Ukraine, one U.S. company, Lightbridge, sent samples for irradiation in a Russian fast reactor, but that is no longer practical. Meanwhile, testing infrastructure has withered; various test reactors around the world have gotten old and have closed, including the Halden reactor in Norway, in 2016, which had been running since 1958.

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Nebraska Looks at New Nuclear

The Nebraska Public Power District, operator of Nebraska’s sole surviving nuclear reactor, is spending $1 million in federal aid to evaluate 15 sites for a small modular reactor and identify four leading candidates.

The state legislature set aside money for this effort from the American Rescue Plan Act, which has provisions to help stabilize and de-carbonize the electric grid and reduce the effects of the pandemic on low-income communities. Two years ago, the state suffered rolling blackouts.

The legislature also voted in 2021 to make nuclear plants eligible for the same incentive Nebraska gives to wind and solar.

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An Off-the-Shelf Design for a Small Modular Reactor

The Nuclear Regulatory Commission has finished the paperwork and published a final rule, certifying NuScale Power’s small modular reactor. The designation means that a qualified utility with an approved site can expect a quick hearing to determine if the site is compatible with the design, and then a combined license to build and operate the plant. Opponents cannot challenge the design itself, making a NuScale reactor less vulnerable to the licensing delays that plagued the current generation of reactors.

It's not quite over, though; the design approved by the NRC is what NuScale originally applied for, a module that produces 50 megawatts. Later, NuScale reanalyzed the design and said that each module could safely produce 77 megawatts, an output level that it then promised its customers. Now it needs the NRC to approve the higher output.

The design is the seventh approved by the NRC and the first for an SMR. The only one of the approved designs that has been built so far is the Westinghouse AP1000, and the first U.S. reactor of that design, Vogtle 3, near Augusta, Ga., is expected to enter commercial operation later this year. That project was beset with a variety of delays and cost-overruns, one of which was related to the licensing system that Westinghouse (and now NuScale) chose to govern their project.

Under the licensing system that NuScale chose, opponents can’t challenge the design but any deviation from the designs that were approved by the NRC requires a license amendment, which can be cumbersome. Under the old system, the plant was built before the license was approved, and the builders only had to show that the finished product met NRC requirements.

NuScale has a domestic customer, the Utah Associated Municipal Power Systems, and a site, at the Idaho National Laboratory, for the first U.S. plant. It also has preliminary agreements in place to sell reactors to several European buyers.

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Have Reactor, Will Travel

Increased interest in advanced nuclear energy coincides with increased interest in space exploration, and specifically, Mars. NASA and DARPA, the Defense Advanced Research Projects Agency, are looking at several propulsion concepts. Some were tried out when the space race began in the Cold War, but haven’t gotten much attention since.

Chemical rockets are probably indispensable for producing the huge bursts of thrust needed to get off the surface of the Earth, but the big challenge for long trips is launching all the fuel needed to keep them running. Nuclear systems don’t produce nearly as much thrust, but they can run steadily in flight for much longer periods, and the mass-to-energy ratio of the fuel is much more favorable.

A nuclear rocket that could add modest amounts of thrust for weeks at a time could shorten the trip to Mars substantially, reducing the logistical problem of getting astronauts there and back with enough food, water, and air to sustain them. The goal is to shorten the trip from the seven months now typical for robot probes to several weeks.

A nuclear reactor could heat hydrogen and shoot it out the back of a rocket nozzle. Or it could spit out ionized xenon gas, among other possibilities.

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