Between 1954 and 1977, the U.S. Army Nuclear Power Program developed a series of small, modular nuclear reactors intended to provide electrical power and heating to remote installations which would otherwise require continuous logistical support to supply fuel. One of the project’s first pilot installations was the PM-1 reactor installed at the U.S. Air Force’s Sundance Air Force Station radar base in Wyoming. Located on a mountain peak at 1800 metres above sea level, 150 km from the nearest railhead, the ability to run two years between refuelling was seen as a great advantage.
The PM-1 reactor was a pressurised water design, producing 1.25 megawatts of electrical power, plus space heating for the installation. The reactor, designed and built by the Martin Company, was shipped in 16 packages, each transportable by a C-130 cargo plane or by road or rail and assembled on site. The reactor was fuelled by uranium enriched to 93% U-235 and would run two years on a fuel load. The reactor and power plant was designed to operate with a staff of two: reactor operator and maintenance technician.
The reactor went critical on site on 1962-02-25 and the plant remained in operation until 1968. It served as a pilot plant for the similar PM-3A reactor installed at McMurdo Station in Antarctica, as described in the post here on 2023-02-24, “Nuclear Power for Antarctica”.