MH-1A



MH-1A was a pressurized water reactor and the first floating nuclear power station. One of a series of reactors in the US Army Nuclear Power Program, its designation stood for mobile, high power.

History
The reactor was built for the U.S. Army by Martin Marietta under a $17,000,000 contract (August 1961), with construction starting in 1963. The reactor was built in Sturgis, a converted Liberty ship formerly known as SS Charles H. Cugle. The original ship propulsion system was removed,and a single-loop pressurized water reactor, in a 350 ton containment vessel, was installed, using low enriched uranium (4% to 7% 235U) as fuel. After testing at Fort Belvoir for five months starting in January 1967, "Sturgis" was towed to the Panama Canal Zone. The reactor supplied 10 MW electricity to the Panama Canal Zone from October 1968 to 1975.

Sturgis (named after General Samuel D. Sturgis, Jr.) was hull number 3145, and not as sometimes supposed SS William Sturgis, another liberty ship (hull number 800, scrapped in 1969).

Fort Belvoir, Virginia was the headquarters of the Army Corps of Engineers and, beginning in 1954, the corps' newly created Army Reactors Branch. This unit was established by the Department of Defense to develop compact nuclear power plants that could be utilized to supply heat and power at remote locations. The army's first nuclear power reactor, the SM-1 was built at Fort Belvoir in 1955-57, and was located in the southeast "corner" of the post, alongside Gunston Cove, off the Potomac River. The SM-1 reactor, also known as the Army Package Reactor Program, was used to train nuclear operations personnel for all three services. For that reason, the MH-1A was installed and tested aboard the Sturgis while it was moored in Gunston Cove, near the SM-1 facility.

Dredging of a channel between the main course of the Potomac River to the shoreline of Gunston Cove began on 30 November 1964. At the same time, construction of an access road, power lines and the pier began, just below the SM-1 reactor facility. The Sturgis arrived at the new Gunston Cove pier on 22 April 1966, having been towed from Mobile, Alabama. The MH-1A reactor first went critical on 24 January 1967 and was formally "accepted" by the Army on 25 July 1967. The Sturgis remained at the pier for another 11 months, supplying power to Fort Belvoir, while the Corps of Engineers sought a suitable permanent site. In spring 1968, the US State Department entered into negotiations with the Panama Canal Company, and the Sturgis was towed out of Gunston Gove in late July 1968, arriving Gatun Lake on 7 August.


 * The MH-1A had an elaborate analog-computer-powered simulator installed at Ft. Belvoir.
 * The MH-1A simulator was obtained by Memphis State University Center for Nuclear Studies in the early 1980s, but was never restored or returned to operational service. Its fate is unknown after the Center for Nuclear Studies closed.

Sturgis in Panama Canal Zone, 1968-1976
A water shortage in early 1968 jeopardized both the efficient operation of the Panama Canal locks and the production of hydroelectric power for the Canal Zone. Vast amounts of water were required to operate the locks and the water level on Gatun Lake fell drastically during the December-to-May dry season, and necessitated curtailment of operations at Gatun Hydroelectric Station.

To help out further, the Andrew J. Weber, a diesel-fueled power barge of 20 megawatts capacity was deployed to the Canal Zone in November 1968. These two barges not only contributed to meeting the Canal Zone’s power requirements, but also made possible the saving of vast quantities of water that otherwise would have been needed to operate the hydroelectric power station. The Corps of Engineers estimates that over one trillion gallons were saved (or, rather, freed-up) between October 1968 and October 1972- enough to permit fifteen additional ships to pass through the locks of the Canal each day.

The MH-1A plant aboard the Sturgis replaced power from a hydroelectric plant in Panama, allowing lake water to instead be used for navigation. The ship was moored in Gatun Lake, between the Gatun Locks and the Chagris dam spillway. According to a power engineer who served aboard the Sturgis while it was in Panama, the ship provided augmentation power-generation capacity to the entire Canal Zone, especially during the dry season, which allowed more of the water capacity of Gatun Lake to be used for navigation purposes rather than for hydroelectric power generation. Therefore, the lake could be kept at higher levels. This was critical during this period because of the emergence and growth of the "Panamax" container ship, which tested the draft and dimensional limits of the Canal. Had the Sturgis not been in the Canal Zone, more water would have been used for power generation. This would have lowered the level of Gatun Lake and reduced the allowable draft for transiting vessels, which would have resulted in fewer vessels transiting the canal. The Sturgis was replaced by two 21-MW Hitachi turbines, one on the Pacific side of the isthmus and one on the Atlantic side.


 * After one year of operations in the Canal Zone, the MH-1A reactor had to be refueled, a process which took one week (17-25 October 1969), according to a 1969 Corps of Engineers report.


 * According to a 2001 report by the Federation of American Scientists, the MH-1A reactor had a total of five cores during its operational life. It used low-enriched uranium (LEU) in the range of 4 to 7 percent, with a total amount of uranium-235 supplied being 541.4 kilograms (for the 5 cores).

Deactivated and Mothballed at James River, 1977
The MH-1A plant was retired from service in 1976 since the Army Reactor Program had been discontinued, and, as a unique prototype, operation cost for the unit was high. Also, the Panama Canal Company acquired additional land based electrical capacity and in 1976 it was determined that the Sturgis was no longer needed. It operated at an effective annual capacity factor of 0.56 over nine years.

Between December 1976 - January 1977, the power barge was towed back to the United States, sustaining storm-related damage so severe that it had to divert to the Military Ocean Terminal at Sunny Point, North Carolina, and undergo temporary structural repairs. Following repairs, the Sturgis was towed to Fort Belvoir, arriving in March 1977. Fuel was removed from the reactor at Fort Belvoir, shipped to the Savannah River Site, and the plant was put into SAFSTOR (safe storage), with decontamination and physical barriers to prevent release of radioactivity. The Sturgis is now moored in the James River outside Fort Eustis, Virginia and is part of the James River Reserve Fleet.