The Department of Energy's (DOE) Argonne National Laboratory will partner with three companies as part of a voucher program offered by the DOE's Office of Nuclear Energy's Accelerated Nuclear Energy Innovation Portal (GAIN) program. As part of the project, Argonne will help industry develop a range of new reactor and fuel cycle concepts that go beyond today's traditional large water-cooled reactors.

Under a contract, Argonne National Laboratory will work with Radiant Industries, a California-based start-up, to perform numerical simulations of heat generation and removal in Radiant Advanced's high-temperature gas-cooled microreactor concept. The advantage of the microreactor, called Kaleidos, is that it is portable, says Argonne National Laboratory nuclear engineer April Novak, one of the lab's Maria Goeppert Mayer Fellows.

"This type of reactor is small and very different from conventional reactors," Novak said. It targets various applications of nuclear energy, such as remote communities and electric vehicle charging, and I'm excited to be working on this because I find it rewarding to see Argonne's research applied to commercial concepts that have the potential to expand nuclear's role in combating climate change."

Novak will help create a high-fidelity computational fluid dynamics model of the microreactor under shutdown conditions, including its passive cooling system. One heat removal system, called an air jacket, consists of a thin layer of ambient air between the reactor and the shield. "The sleeve is designed to passively remove decay heat and improve the safety of nuclear power production," Novak said.

Doug Bernauer, Radiant's CEO, said, "The gas jacket modeling work in collaboration with Argonne National Laboratory will be truly novel and a key requirement with unique advantages for passive cooling, and we plan to be the first new commercial reactor design to achieve fuel testing in more than 50 years. Full commercialization of advanced reactors requires extensive, ongoing collaboration between the Department of Energy and multiple national laboratories, such as Argonne National Laboratory and Idaho National Laboratory. We are very excited about this award as it is another key step in that direction."

Novak said the prize will also help researchers determine the heat source in the reactor based on how the fuel is burned. The work Argonne National Laboratory is doing on Kaleidos through the GAIN voucher is an extension of earlier work done through the Nuclear Advanced Modeling and Simulation Program.

In a separate GAIN award program, Argonne nuclear engineer Darius Lisowski will lead a research team working with Oklo, a nuclear company also based in California, on small fast reactors as part of the Aurora product line.

Lisowski's team will help test the high-flow coolant on Oklo's needle bundle. The pins were manufactured and tested using capabilities recently established at Argonne. "We originally built this facility for multipurpose test reactors, and our experience will serve us well in helping Oklo bring their reactor concept to life," Lisowski said.

Argonne National Laboratory has facilities for testing the flow performance of needle bundles. "Basically, because of the internal geometry, there's a lot of interesting physics about how the coolant mixture flows through the pin, and we're looking at extreme flow conditions - more than 800 gallons of water per minute - to see the pressure drop in the various parts of the component," Lisowski said.

The third project funded by GAIN will involve a team led by Argonne nuclear engineer Melissa Rose that will work on reactors powered and cooled by a mixture of molten salt. Although there are no commercially available molten salt reactors, Mr Ross said: "Molten salt reactors are good for recovering nuclear fuel through high-temperature processing, and Argonne has developed a technology. In theory, about 97% of nuclear fuel could be used; It's just contaminated by fission products that have to be separated out, and a molten salt reactor can bring us closer to a closed fuel cycle where most of the nuclear fuel is used over and over again."

In a molten salt reactor, the fuel dissolves in molten salt and the liquid flows through the reactor. For her GAIN grant, Rose works with Alabama-based Flibe Energy. Flibe is looking for a molten fluoride reactor that can be used for both energy production and medical isotopes for life-saving cancer treatments.

Argonne develops and maintains specialized facilities that Rose and her colleagues will use to measure the properties of these molten salts. From melting point to phase behavior to heat capacity and thermal diffusivity, Argonne's analysis of these properties will help Flibe get their reactor closer to construction. This is Argonne's seventh GAIN voucher measuring properties to support a molten salt reactor.