Milestone Advances Microreactor Toward Criticality Under DOE Reactor Pilot Program; Construction Nears Completion
Austin, Texas — Last Energy, an advanced nuclear technology company, today announced that the U.S. Department of Energy (DOE) has approved the company’s Preliminary Documented Safety Analysis (PDSA) for its PWR-5 pilot reactor at Texas A&M–RELLIS.
The PDSA establishes the preliminary safety basis for Last Energy’s reactor, facility, and planned operations, marking a critical step in the DOE authorization process. With this approval, Last Energy advances toward DOE authorization to bring nuclear fuel on site, demonstrate criticality, and operate the reactor.
“PDSA approval is a major step in moving the PWR-5 from construction into operations,” said Adam Lenarz, Vice President of Development at Last Energy. “Our team has advanced building construction, equipment procurement, fuel fabrication, and safety documentation in parallel, reflecting the disciplined execution this project requires. With this milestone complete, we are focused on finalizing the DSA, the final safety analysis needed to secure DOE authorization for fuel receipt, criticality, and reactor operations.”
In August 2025, Last Energy was selected to participate in DOE’s Reactor Pilot Program, created under President Trump’s Executive Order 14301, “Reforming Nuclear Reactor Testing at the Department of Energy.” The program is designed to accelerate reactor demonstration by authorizing test reactors through DOE’s process.
Since then, Last Energy signed its land lease with Texas A&M–RELLIS, began construction in 2026, procured and delivered key reactor components to site, and advanced construction of the reactor building. Last Energy’s fuel has now been manufactured, and the company is actively progressing its Documented Safety Analysis with DOE.
Last Energy’s PWR-5 uses the same physical reactor geometry as the company’s commercial PWR-20, with reduced fuel enrichment scaled for 5 MW of electrical output. The pilot reactor will demonstrate low-power criticality before progressing to electricity generation designed for commercial deployment. The project builds on Last Energy’s strategy to transform nuclear plants from bespoke construction projects into standardized, factory-fabricated products.
The PWR-5 pilot project is a direct bridge to Last Energy’s commercial PWR-20 deployment model. The PWR-20 is a 20 MWe micro modular nuclear plant designed for factory fabrication, standard road transport, rapid on-site assembly, and 24/7 baseload power delivery to industrial customers, data centers, and other high-energy users.
About Last Energy:
- Last Energy is a pioneering U.S. technology company focused on the fleet-scale deployment and operation of next-generation nuclear assets. With one of the industry’s largest commercial microreactor pipelines, the company aims to locate its proprietary 20 MWe microreactor in strategic clusters near AI data centers and industrial facilities.
- Last Energy’s commercial product, the PWR-20, is a 20 MWe micro modular nuclear plant designed for factory fabrication, standard road transport, rapid on-site assembly, and 24/7 baseload power delivery.
- Last Energy intentionally uses proven pressurized water reactor technology, standard low-enriched uranium fuel, and existing supply chains to reduce technical risk and accelerate project delivery.
- Last Energy’s core innovation is its integrated reactor containment: a 1,000-ton, hermetically sealed steel structure designed for factory fabrication and no-access operation. By integrating all primary systems into a single hermetic containment, the reactor is engineered for high-throughput manufacturability and repeatable deployment.
- With a growing pipeline of microreactor projects across the U.S., UK, and Europe, Last Energy is building a repeatable model for deploying nuclear power where high-energy customers need it.
Contact: media@lastenergy.com
