X-energy’s helium coolant and fuel handling test facility gets EA/FONSI

March 11, 2024, 12:00PMNuclear News
Concept art of the planned X-energy helium test facility. (Image: DOE OCED)

The Department of Energy’s Office of Clean Energy Demonstrations issued a final environmental assessment (EA) and finding of no significant impact in February for a cost-shared X-energy project to construct and operate a helium test facility (HTF) in Oak Ridge, Tenn. According to the EA, construction would begin in early 2024 and take X-energy and its contracted partner, Kinectrics, about one year to complete. the facility would then operate for six years, with the possibility of extensions for up to an additional 20 years, to test equipment for a demonstration of X-energy’s high-temperature, gas-cooled reactor technology and also to “serve the reactor community at large as the technology continues to develop and is adopted around the world.”

First in a while: “X-energy is required to test critical structures, systems, and components (SSCs) that are first-in-a-while (FIAW) and would operate in a harsh, high-temperature helium environment in the reactor,” the EA states. “The purpose of the HTF is to replicate the reactor environment without the radioactive material and to be capable of providing the required test conditions for qualifying the components in support of the Xe-100, a high-temperature, gas-cooled small modular reactor (SMR).”

X-energy was selected for a full-scale cost-shared reactor demonstration under the Advanced Reactor Demonstration Program in October 2020. In February 2021, the DOE entered a cooperative agreement with X-energy that included support for the construction and operation of a helium test facility and a fuel fabrication facility. And in May 2023, X-energy and Kinectrics announced their partnership for the design, construction, and operation of the test facility.

The DOE also plans to support the coolant testing plans of TerraPower, its other ARDP demo awardee. A draft EA for a TerraPower sodium “test and fill” facility in Wyoming was released in November 2023.

Project parameters: According to the EA, X-energy’s HTF would be constructed and operated at the Horizon Center Industrial Park, Development Area 7, in Oak Ridge, Tenn., on land owned by Kinectrics. Between 30 and 40 people would be employed during the construction of the facility, with 10–15 people working there during operations.

The HTF will be a 11,500-square-foot building, 18 feet high with a tower reaching about 85 feet. It will house a fuel handling system with auxiliary gas service system, reactivity control and shutdown system, helium circulator system, helium purification system, Xe-100 plant control and reactor protection system, and a representative reactor pressure vessel. An access road, stepdown transformer, laydown areas, and a parking lot would also be required.

Nearby, on another site in the industrial park, X-energy plans to operate a TRISO-X fuel facility to fabricate high-assay low-enriched uranium TRISO-packed spherical fuel for the Xe-100. TRISO-X LLC, an X-energy subsidiary, submitted an application to the Nuclear Regulatory Commission for that facility in April 2022.

Circulating spheres: The fuel handling system test equipment in the facility would contain a scaled Xe-100 fuel handling system and a vessel representing the Xe-100 reactor, through which billiard ball–sized spheres—simulating the Xe-100’s TRISO fuel pebbles—will circulate in a high-pressure, high-temperature environment. The main functions, associated control sequences, and interfaces being tested include loading new spheres, unloading spent spheres, recirculating spheres, storing spent or damaged spheres, and tracking the flow of spheres in the vessel.

A helium circulator system test loop would test a full-scale Xe-100 helium circulator and support components. That loop will make use of a check valve, flow meter, and heat exchangers to regulate flow resistance and temperatures during testing.

EA and FONSI: Because the helium test facility would be constructed on a 15-acre greenfield site and require the clearing of five acres of forested land, the DOE determined that an EA was required. And after carrying out the EA, the DOE concluded that an environmental impact statement was not necessary and issued a finding of no significant impact on February 16. The NRC does not have a role in the regulation of the nonnuclear facility.

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