NRC Issues First Advanced Reactor Construction Permit for Xe-100 at Dow Seadrift

The U.S. Nuclear Regulatory Commission has issued a construction permit to Dow and X-energy for four helium-cooled Xe-100 Generation IV high-temperature gas-cooled reactors at Dow's Seadrift, Texas chemical site. The Long Mott Generating Station project totals 320 MWe and 800 MWt, with each unit rated at 80 MWe and 200 MWt.

A first for HTGR licensing

The permit is the NRC's first construction permit for an HTGR in nearly 60 years. It is also the first multimodule advanced facility with a pebble-bed core and online refueling, and the first HTGR assessed under the NRC's risk-informed Licensing Modernization Project framework.

The licensing milestone matters for HALEU because the Xe-100 uses TRISO-X coated-particle fuel. X-energy's fuel subsidiary, TRISO-X, received an initial HALEU allocation in April 2025 through the DOE HALEU Availability Program to manufacture fuel for the first core loads at Long Mott.

Federal cost share and program history

DOE has committed more than $2.15 billion in cost-shared federal funding, plus decades of foundational research and fuel supply programs, to support the Long Mott project. Most of the funding flows through the Advanced Reactor Demonstration Program under 50/50 cost-share agreements.

X-energy was selected in October 2020 as one of two ARDP lead demonstration awardees to design, license and build an Xe-100 reactor and fuel facility. An initial cooperative agreement of up to $1.2 billion was finalized in early 2021, according to the project description.

Construction still awaits Dow's capital decision

The NRC permit does not start construction. Dow must complete internal capital allocations, X-energy must finalize Xe-100 designs, supply chains for long-lead components and materials must be established, and an Operating Licence application must be prepared.

The preliminary investment decision is expected in 2027. First power and steam are targeted for the early 2030s, around 2033, over a 60-year lifespan.

For the HALEU market, the Seadrift permit validates a licensing pathway for a fuel form that depends on high-assay low-enriched uranium and TRISO fabrication. It also shows that federal cost share and DOE fuel programs remain central to moving advanced reactors from design to construction.

This article was assisted by AI analysis. Please refer to the original source for official information.