page_title: Army Nuclear Power Program
section_title: List of plants
hierarchical_section_title: Army Nuclear Power Program / List of plants
caption_attribution_description: English: Photo of MH-1A Nuclear Power Plant
context_page_description: The Army Nuclear Power Program was a program of the United States Army to develop small pressurized water and boiling water nuclear power reactors to generate electrical and space-heating energy primarily at remote, relatively inaccessible sites. The ANPP had several accomplishments, but ultimately it was considered to be "a solution in search of a problem." The U.S. Army Engineer Reactors Group managed this program and it was headquartered at Fort Belvoir, Virginia. The program began in 1954 and had effectively terminated by about 1977, with the last class of NPP operators graduating in 1977. Work continued for some time thereafter either for decommissioning of the plants or placing them into SAFSTOR. The current development of small modular reactors has led to a renewed interest in military applications.
context_section_description: Eight plants were constructed. Due to the requirement for a small physical size, all these reactors other than the MH-1A used highly enriched uranium (HEU). The MH-1A had more space to work with, and more weight-carrying capacity, so this was a low-enrichment reactor; i.e., larger and heavier. The MH-1A was briefly considered for use in Vietnam, but the idea of anything nuclear in Vietnam was quickly rejected by the State Department.
  The plants are listed in order of their initial criticality. See the gallery of photos in the next section. Sources for this data include the only known book on the ANPP, by Suid, and a DOE document.
  SM-1: 2 MW electric. Fort Belvoir, Virginia, Initial criticality April 8, 1957 (several months before the Shippingport Reactor) and the first U.S. nuclear power plant to be connected to an electrical grid. Used primarily for training and testing, rather than power generation for Ft. Belvoir. The plant was designed by the American Locomotive Company (renamed ALCO Products, in 1955), and was the first reactor developed under the Army Nuclear Power Program. See the SM-1 image gallery, below. This plant was a tri-service training facility, with both the US Navy and Air Force sending personnel to be trained on shore-based facilities (the Navy had a different stand-alone program for ship-based nuclear power, which is still in operation). The SM-1 and associated training facilities at Ft. Belvoir were the only training facility for shore-based military power plants. The plant cooled its condensers using the waters of the Potomac River. For about the first 10 years of its operation, the SM-1 unknowingly released tritium into the waters of the Chesapeake Bay, until the development of the Packard Tri-Carb detector, which was the first detector system capable of detecting the low-energy beta decay of tritium. The instrumentation in the SM-1 pre-dated the development of solid-state devices and used vacuum tubes.
  SL-1: Boiling water reactor, 200 kW electrical, 400 kW thermal for heating, National Reactor Testing Station, Idaho. Initial criticality August 11, 1958. The SL-1 was designed by the Argonne National Laboratory to gain experience in boiling water reactor operations, develop performance characteristics, train military crews, and test components. Combustion Engineering was awarded a contract by the AEC to operate the SL-1 and in turn employed the Army's military operating crew to continue running the plant. This BWR was specifically designed to power DEW line stations.
  On January 3, 1961, the reactor was being prepared for restart after a shutdown of eleven days over the holidays. Maintenance procedures were in progress, which required the main central control rod to be manually withdrawn a few inches to reconnect it to its drive mechanism; at 9:01 p.m. this rod was suddenly withdrawn too far, causing SL-1 to go prompt critical instantly. In four milliseconds, the heat generated by the resulting enormous power surge caused water surrounding the core to begin to explosively vaporize. The water vapor caused a pressure wave to strike the top of the reactor vessel, causing water and steam to spray from the top of the vessel. This extreme form of water hammer propelled control rods, shield plugs, and the entire reactor vessel upwards. A later investigation concluded that the 26,000-pound (12,000 kg) vessel had jumped 9 feet 1 inch (2.77 m) and the upper control rod drive mechanisms had struck the ceiling of the reactor building prior to settling back into its original location. The spray of water and steam knocked two operators onto the floor, killing one and severely injuring another. One of the shield plugs on top of the reactor vessel impaled the third man through his groin and exited his shoulder, pinning him to the ceiling. The victims were Army Specialists John A. Byrnes (age 27) and Richard Leroy McKinley (age 22), and Navy Seabee Construction Electrician First Class (CE1) Richard C. Legg (age 26).
  It was later established that Byrnes (the reactor operator) had lifted the rod and caused the excursio
caption: MH-1A 
   Power Barge Sturgis, Gunston Cove, Ft. Belvoir,
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