US Army’s oldest test base gets 390MW molten salt nuclear plant fueled by U-235

The US Army’s oldest active proving ground and test base will reportedly receive a 390-megawatt (MW) Generation IV molten salt nuclear plant to boost the site’s energy resilience.

The Aberdeen Proving Ground (APG) in Maryland was established on October 20, 1917. It will now host a nuclear power plant based on Terrestrial Energy’s Integral Molten Salt Reactor (IMSR) technology. The project is being developed by clean energy company Ameresco.

For the novel project, the two companies will combine nuclear power with natural gas generation. The facility will supply electricity to the regional grid and provide APG with a more reliable power supply.

The effort followed a competitive Army selection process. “We are so excited to advance this critical project at Aberdeen Proving Ground and support the US Army’s efforts to strengthen long-term energy resilience and security,” Nicole Bulgarino, Ameresco co-president, pointed out.

A molten salt reactor plant

Terrestrial Energy’s IMSR Plant is a Generation IV nuclear power system designed to produce both electricity and high-temperature industrial heat. It uses molten salt reactor technology. It combines three main operating traits, including high temperature, low pressure and inherent safety.

The plant will generate 390 MWe of electricity. It also uses a modular architecture intended to enable faster construction at the site. According to the companies, its output can also be adapted to meet different energy demands, including those of energy-intensive industrial facilities.

The Aberdeen Proving Ground located in the state of Maryland, USA. Credit: Ameresco

Terrestrial Energy stated that the plant will provide firm power, meaning its output will not depend on the weather. “Terrestrial Energy is excited to be partnering with Ameresco to support the US Army’s Strategic Capital Initiatives to build advanced energy resilience at one of the country’s most critical research and testing installations,” Simon Irish, Terrestrial Energy CEO, said.

Irish noted that the effort is expected to support power reliability and the nation’s energy security. “Ameresco is at the forefront of mission-critical projects, and we are honored to be partnering with them,” he added.

Fueled by low-enriched uranium

In addition, the plant will use standard-assay low-enriched uranium, or SALEU, which has less than five percent uranium-235 (U-235). This is a rare radioactive uranium isotope that makes up only about 0.72 percent of all natural uranium and is capable of sustaining a nuclear chain reaction.

This will allow the plant to use existing nuclear fuel supply chains instead of the higher-enriched fuel required by some advanced reactors. The initiative will be developed in phases. It will use both natural gas and advanced nuclear power.

The effort builds on a deal announced by Ameresco and Terrestrial Energy in June 2025. Under the partnership, the companies agreed to identify potential sites and pursue IMSR Plant projects across the United States.

“Ameresco is pleased to partner with Terrestrial Energy as we work together to bring forward innovative, reliable power solutions that can help meet the evolving energy needs of the US Army,” Bulgarino concluded in a press release.

Terrestrial Energy intends to bring its first IMSR plants online at several US sites in the early 2030s.