TRISO-X, the fuel subsidiary of X-energy, received an initial allocation of high-assay low-enriched uranium in April 2025 through the DOE HALEU Availability Program. The allocation is intended to manufacture fuel for the first core loads of the Long Mott Generating Station, the Dow/X-energy Xe-100 project in Seadrift, Texas.

From irradiation data to qualified fuel

The allocation rests on a long qualification record. Over 20 years, from 2003 to 2023, DOE irradiation testing and production specifications established the safety data used to qualify TRISO-X coated-particle fuel.

TRISO-X fuel uses tristructural isotropic coated particles designed to retain fission products under accident conditions. The Xe-100 reactors use this fuel with passive safety features, shrinking the emergency planning zone to 400 metres.

Why the HALEU allocation matters

HALEU allocation is a prerequisite for manufacturing first cores, but it is not the same as completed fuel fabrication. TRISO-X must convert allocated HALEU into coated-particle fuel that meets production specifications and licensing requirements. The DOE program is designed to bridge the gap between enrichment output and fuel manufacturers that need material before commercial supply chains are fully established.

The NRC's construction permit for the four-unit Long Mott project, announced in 2026, adds a licensing anchor for the fuel. The project totals 320 MWe and 800 MWt, with four 80 MWe / 200 MWt helium-cooled Xe-100 units. It is the first NRC construction permit for an HTGR in nearly 60 years and the first multimodule advanced facility with a pebble-bed core and online refueling.

Execution questions remain

Construction has not started. Dow must complete internal capital allocations, X-energy must finalize designs and long-lead supply chains, and an operating licence application must be prepared. The preliminary investment decision is expected in 2027, with first power and steam targeted for the early 2030s over a 60-year lifespan.

For the HALEU supply chain, TRISO-X's allocation is an early test of whether DOE material can support fuel qualification and first-core manufacturing at a commercial advanced reactor project. The answer will depend on fabrication yields, specification compliance and the pace of NRC licensing.

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