Plans for TerraPower’s “test and fill” sodium facility covered in draft EA

November 20, 2023, 3:00PMNuclear News
Image from the DOE’s draft EA showing a rendering of the TFF building. (Image: DOE)

The Department of Energy’s Office of Clean Energy Demonstrations issued a draft environmental assessment (EA) in early November for a test and fill facility (TFF) that TerraPower plans to build in Kemmerer, Wyo.—the town selected two years ago to host the company’s first Natrium sodium fast reactor. The draft EA, open for comment through December 1, describes TerraPower’s plans to construct a nonnuclear facility that would safely store about 400,000 gallons of sodium to test coolant system designs and ultimately fill the planned reactor.

The Natrium demonstration project, which was awarded cost-shared funding under the DOE’s Advanced Reactor Demonstration Program (ARDP), includes three separate projects: the TFF, a fuel fabrication facility, and the reactor itself. In December 2022, TerraPower announced a two-year delay in estimated reactor operation, pushing a planned 2028 operation date out to 2030. While the TFF and the reactor itself will be constructed in Kemmerer, the fuel fabrication facility is planned for Wilmington, N.C., near existing fuel fabrication facilities of TerraPower’s Natrium design collaborator, GE Hitachi.

The plan and its purpose: The DOE plans to provide federal funds under TerraPower’s ARDP award to construct and operate the TFF as a testing site for the Natrium reactor’s nonnuclear operating systems, in particular, the sodium coolant system. The facility would receive, sample, process, and store liquid sodium; deliver it to perform component tests within the TFF; and ultimately deliver it to the reactor that is referred to in the draft EA as “Kemmerer Unit 1.”

According to the draft EA, “TerraPower has deemed it prudent to test prototypes of Natrium equipment to identify possible design improvements ahead of equipment implementation in a Natrium reactor. Therefore, to minimize risk and increase efficiencies, construction of a test facility (the TFF) is planned. TerraPower would build the TFF in advance of, and separate from, Kemmerer Unit 1. . . . No additional TFFs would be built as part of the development of future Natrium reactor plant sites.”

Three main missions of the TFF are identified in the draft EA: to support prototype-scale sodium testing/qualification for Kemmerer-1, to advance technologies for future sodium fast reactors, and to provide the initial sodium fill for Kemmerer-1.

According to the DOE, “The research conducted at this facility would serve the sodium reactor community around the world, as interest in this technology continues to grow globally.” The DOE expects the TFF to operate for about 20 years, with the possibility of future extensions.

In the ground: The TFF would include an outside equipment area, equipped with backup diesel generator, liquid argon, liquid nitrogen, and water storage tanks; an office trailer; and the sodium test building itself. The site would not require water or sewer hookups.

The steel test building will have a footprint of 125 feet by 220 feet and will be 108 feet tall at its highest point. The building will be built over “as many as eight vertically oriented, cylindrical, subsurface shafts.” Those drilled shafts, ranging from about 12 to 39 feet in outer diameter, will be lined with steel and used to house sodium test tanks and equipment platforms.

Sodium management: Sodium will be trucked to the TFF using 20-metric-ton ISO shipping containers. An estimated 115–130 shipping containers will be received.

According to the draft EA, “When the sodium container reaches the TFF, it would be pulled into a loading dock with specialized equipment for receipt of sodium. A set of heating coils inside the ISO container enable an applicable heat transfer oil to be passed through and the sodium safely melted. This process would take about 18 hours. Once molten, additional argon would be pumped into the container pushing the sodium into a holding tank. Once a sample has been chemically tested for purity by a qualified vendor, the sodium would be pumped through a filter. The sodium would be stored in a large external tank of approximately 400,000 gallons until enough is stored for sodium fill operations of Kemmerer Unit 1.”

Sodium will be stored and used under an argon cover gas and kept in steel-lined shafts to eliminate exposure to the environment, according to the draft EA, and each below-grade sodium loop will have a below-grade drain tank for emergency use.

The assessment: In May, the DOE determined that an EA would be required under the National Environmental Policy Act before federal funding could be released for the TFF project. The Nuclear Regulatory Commission has classified the TFF as “a non–safety related commercial structure” and is not involved in authorizing the facility.

EA-2217 describes and analyzes potential impacts to the human environment that would be caused by the proposed project and, as applicable, identifies possible mitigation measures to reduce or eliminate those impacts. The DOE analyzed the following resource areas and issues in the EA: biological resources; socioeconomics; environmental justice; cultural and historic resources; geology and soils; hydrology; infrastructure including emergency services, transportation, and traffic; and accidents and hazards.

The DOE issued the draft EA on November 2 for a 30-day comment period and had scheduled a public meeting in Kemmerer in mid-November. Comments may be submitted by email to

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