The U.S. Department of Energy (DOE) is requesting public input on the draft Environmental Assessment (EA) for TerraPower, LLC’s Test and Fill Facility (TFF) Project located in Lincoln County, Wyoming (the proposed project).

DOE is proposing to provide federal funding to TerraPower to construct and operate this facility under the Advanced Reactor Demonstration Program. The Test and Fill Facility is designed as testing site for the TerraPower Natrium reactor’s non-nuclear operating systems, particularly those relating to the design’s sodium coolant. This facility would receive, sample, process, store, and then deliver liquid sodium to areas where component tests are performed, including the planned Kemmerer Unit 1 reactor. The research conducted at this facility would serve the sodium reactor community around the world, as interest in this technology continues to grow globally. 

DOE will be the lead federal agency in the preparation of the EA.

What’s New

May 2023 - Pursuant to the requirements of the National Environmental Policy Act (NEPA), the U.S. Department of Energy (DOE) has determined that an Environmental Assessment (EA) is required to inform a decision on whether to provide federal funding to TerraPower in support of the TFF Project. The EA will identify and analyze the potential impacts to the human environment that may occur if DOE authorizes the expenditure of federal funding by TerraPower to construct and operate the TFF Project.

November 2023 – DOE released the draft EA (DOE/EA-2217) on November 2, 2023, for a 30-day public comment period. The comment period closes on Friday, December 1st, 2023.  DOE will host one public meeting on November 16, 2023, at the South Lincoln Training and Events Center in Kemmerer, WY from 5:00 to 8:00 PM MST.

Project Schedule

Milestone Opportunity for Public Input
Scoping Period Review project information and provide comments
Analyze public comments and prepare EA  
Public Review of EA Review the draft EA and provide comments
Decision Document See final plan and decision document


Learn more about DOE’s Advanced Reactor Demonstration Program.

Public Comment Opportunities

DOE invites the public to review and comment on a draft EA for the TFF Project. To ensure DOE receives your written comments in time for consideration in preparation of the final EA, please provide them on or before December 1, 2023. Comments received after the end of the comment period will be addressed to the extent practicable. Individual names and addresses (including e-mail) received as part of comment documents normally are considered part of the public record. Persons wishing to withhold names, addresses, or other identifying information from the public record must state this request prominently at the beginning of their submitted comments.

One public meeting will be held to provide an opportunity for interested parties to discuss the Project with resource specialists and submit comments. The meeting will be held on Thursday, November 16, 2023, from 5:00 PM to 8:00 PM MST at the South Lincoln Training and Events Center in Kemmerer, Wyoming.

Comments may be submitted in the following ways:

By email:

By mail:

ATTN: Jessica Buckley
12011 Sunset Hills Rd
Reston, VA 20190