Last Energy has received approval from the U.S. Department of Energy for the Documented Safety Analysis (DSA) of its pilot reactor at the Texas A&M-RELLIS campus, near Bryan-College Station, Texas. This marks the final step in the DOE authorization process: with the DSA now approved, the company moves into the readiness review phase — the last hurdle before the reactor receives its startup authorization.
The DSA is the most comprehensive and detailed safety document required by the DOE. It builds on the Preliminary Documented Safety Analysis (PDSA), which was approved in May 2026, and precisely describes how the reactor and facility will be managed under operating conditions. This approval is no mere formality: it represents the threshold separating the construction phase from actual startup. Work on the RELLIS campus facility has been underway for months and is reported to be nearing completion.
The pilot reactor, designated PWR-5, has a capacity of 5 MWe and uses the same full-scale core as the commercial PWR-20 model. This is a deliberate design choice. By demonstrating performance with a core identical to that of the final product, Last Energy can bypass a significant portion of the technical validation that typically bridges the gap between prototype and commercial version. The PWR-20 is designed for factory manufacturing, standard road transport, and rapid on-site installation — a modular micro-reactor built to be replicated at scale, not constructed one at a time.
The reactor runs on standard low-enriched uranium (LEU) fuel, which has already been procured and is on hand. This choice ensures access to an established commercial supply chain, reducing reliance on specialty supplies or dedicated enrichment processes. For a company targeting large-scale deployment, having an off-the-shelf fuel supply is a structural advantage over competitors relying on exotic or highly enriched fuels.
The project is part of the DOE’s Reactor Pilot Program, established under Executive Order 14301 signed by President Trump in August 2025, which selected eleven projects with the goal of bringing at least three reactors to criticality by July 4, 2026. Four of those projects — Antares Nuclear, Valar Atomics, and Aalo Atomics — have already achieved criticality within that window. Last Energy reached its DSA milestone later than some other program participants, but the near-completion of construction and today’s DSA approval signal that the gap is closing fast.
The Texas A&M System has welcomed the milestone as part of a broader strategy: the RELLIS campus hosts the RELLIS Energy Proving Grounds program, which brings together industry, government, and research to accelerate the development of next-generation energy technologies. Last Energy is not the only player on site, but the PWR-5 is among the most advanced projects in terms of its regulatory journey. With the readiness review now open, reactor startup — and the demonstration that a pressurized water micro-reactor can operate at full scale in a university setting — could be just weeks away.
