The US Army is betting on nuclear microreactors to keep its bases powered even if the grid goes dark

Five companies were chosen to build the microreactors for five bases.

Luke Sharrett/Getty Images The US Army picked five vendors to build nuclear microreactors at five bases.

The Janus Program aims to keep key bases powered if the electric grid goes down.

US officials warn bases could face cyberattacks, strikes, and power disruptions in war.

The US Army announced plans to build nuclear microreactors on five military bases as it tests whether nuclear energy can keep critical operations running if the power grid goes down.

The Janus Program's initial rollout selected five vendors and assigned each to a different installation.

The Army sees the technology as a potential way to ensure bases and troops can operate off-grid during a conflict.

Questions remain about the ultimate cost, which vendors will prove viable, and how widely the Army could deploy the reactors.

On Wednesday, Army officials shared details on the program.

In partnership with the Defense Innovation Unit, the service is awarding up to $2.2 billion in contracts for the first reactors, which will be commercially operated.

The Army said it will provide technical support once the reactors are online.

Army Secretary Dan Driscoll said the contracts are meant to give bases reliable power independent of potentially vulnerable external commercial grids.

For the Janus program, the Army is pairing Antares Nuclear, Inc. with Fort Bragg in North Carolina , BWXT Advanced Technologies, LLC with Fort Campbell in Kentucky, General Atomics Electromagnetic Systems with Fort Hood in Texas, Radiant Industries, Inc. with Fort Benning in Georgia, and Westinghouse Government Services with Fort Drum in New York.

The Army said future sites could include other strategically important or remote installations.