|Fig. 1: Important Antarctic Bases, Including McMurdo Station. (Source: Wikimedia Commons)|
During the 1960s and early 1970s, McMurdo Staion, the largest research base in the Antarctic, was powered by a medium-sized, portable nuclear reactor.  The extreme temperatures in Antarctica necessitated large amounts of fuel oil to maintain operations, making the prospect of nuclear power, an attractive alternative.  During its 10 year lifetime, the nuclear power station produced over 78 million kilowatt hours of electricity and produced 13 million gallons of fresh water using the excess steam in a desalination plant.  Though this device reduced the necessity for fuel imports, it was plagued with problems which ultimately forced its early retirement in 1972. The cost associated with nuclear power in the Antarctic made it impractical, and diesel-electric generators have since powered the base.  The PM-3A nuclear reactor that powered McMurdo Station stands as the only nuclear power station to operate on the Antarctic continent.
The ice-free southern tip of the Hut Point Peninsula on Ross Island in Antarctica has a history of over 100 years of exploration and scientific history and is the site of the present day McMurdo Station.  This site is located just 729 nautical miles from the South Pole and is where Robert F. Scott staged the first expedition to the South Pole in 1902.  The United States established a permanent base at this site beginning in December 1955 as part of Operation Deep Freeze I.  Known as Naval Air Facility McMurdo, this site was to serve as a sea port and logistics base from which to build and support a research facility at the geographic South Pole.  The name McMurdo was chosen to honour a lieutenant on the British ship HMS Terror that discovered Ross Island on an Antarctic expedition in 1841.  In 1958, the site was renamed to McMurdo Station and has since maintained the ability to support a population of over 1200 people.  McMurdo Station serves as the hub for activity in the Antarctic and is currently operated by the United States Antarctic Program (USAP), a division of the Nation Science Foundation (NSF). 
|Fig. 2: PM-3A core. (Source: Wikimedia Commons)|
The decision to install a nuclear power station at McMurdo station was based on several factors.  First, there were difficulties associated with supplying the large fuel demands required for operations. Aircraft, diesel-electric generators, heating units, and various types of land vehicles consumed fuel in excess of half of the total freight delivered to Antarctica in the late 1950s.  To further complicate supply chain logistics, McMurdo can only be accessed by supply ships during the aural summer months (summer in the southern hemisphere), thus requiring all supplies for the entire year to be delivered during this short time frame.  It was concluded that an increased supply of electricity from nuclear power would give rise to a more efficient use of freight, reduced costs, as well as electric heating to replace the fire hazards associated with oil-fired heating units.  In addition, experience would be gained from installing and operating a nuclear power plant in an isolated and harsh environment. 
In August 1960, the United States Congress authorized the design and construction of a nuclear reactor for McMurdo.  That same month, the U.S. Atomic Energy Commission contracted the Martin Marietta Company of Baltimore, Maryland to design, fabricate, test, package, transport, install, and initially operate the PM-3A (A for Antarctic) nuclear reactor on site in Antarctica.  The PM-3A reactor is a portable, medium sized nuclear reactor, the third of its type.  Two others of this type were built and fielded prior to the PM-3A.  The first was the PM-1, also built by Martin, which was used to power a remote radar station in Wyoming as part of the North American Aerospace Defense Command (NORAD).  The PM-2A (A for Arctic) was built by the American Locomotive Company to power the remote US military base known as Camp Century setup in Northern Greenland.  Each of these reactors was in the 1.25-2.0 MW power range, PM-1 and PM-3A were operational by 1962, with PM-2A being operational in 1960. 
|Fig. 3: Components of the PM-3A arriving at McMurdo. (Source: United States Antartcia Program. Courtesy of the NSF)|
The PM-3A nuclear reactor was above all meant to be portable as it was designed with the LC-130 aircraft in mind as its delivery system.  Although McMurdo is accessible by ship, it was originally thought that this reactor would power bases inland such as that located at the South Pole which are accessible only by aircraft.  For reliability and transportability reasons, the PM-3A was designed to be a pressurized water reactor.  Its core utilized highly enriched uranium, 93.1% in relative amount of the isotope U-235, whose fuel assembly was roughly the size of an oil drum.  Fig. 2 shows the installation of the PM-3A core onsite. The reactor arrived in modules at McMurdo in December of 1961 by way of the USNS Arneb.  Fig. 3 shows one of the nuclear reactor modules being unloaded at McMurdo. The PM-3A was assembled on a foundation of solid volcanic rock at an altitude of 300 feet on the side of Observation Hill, a site that overlooks McMurdo Station.  Fig. 4 shows the completed reactor site overlooking McMurdo Station.
The PM-3A was operated by the Naval Nuclear Propulsion Unit consisting of a crew of 25.  The reactor went critical in March of 1962 and supplied useful electricity to McMurdo in July of 1962.  It took a total of 23 months to complete testing and debugging of the PM-3A nuclear plant.  After this time, control of the plant was turned over from the Martin Company to the US Navy.  Once fully operational, the role of the plant was twofold, to produce electricity for McMurdo in the amount of 1.8 MW as well as to produce steam to operate a desalination plant for the production fresh drinking water in the amount of 14,000 gallons per day. 
With a total of 438 malfunctions during its operational lifetime from 1964 to 1972, the reactor at McMurdo proved to be an unreliable source of power generation, available only 72% of the time.  Because of this, in May of 1972, it was determined by an independent assessment from the Bechtel Corporation that the PM-3A was not cost effective and that replacement with modern diesel-electric generators would require less staff and would also be more reliable.  In September 1972, the PM-3A was shut down for routine maintenance and inspection.  It was determined that conditions existed in the system for chloride stress corrosion cracking, a situation where sudden failure can occur in normally ductile materials under tension in a corrosive environment. [1,6] Inspection of a an accessible section of pipe revealed no incidences of this occurring, however, the Navy refused to rule out cracking on surfaces which could not be inspected and thus called for a full dismantling and inspection of the reactor before it could be deemed safe.  The cost associated with this full inspection and possible repair of reactor components was a major factor in the decision to decommission the plant. 
|Fig. 4: Nuclear power plant on observation hill circa 1965. (Source: Wikimedia Commons)|
After 10 years of operation, the PM-3A was permanently shut down in 1972, achieving only half of the expected design life of 20 years.  The next step was clean up of the reactor site. The PM-3A and generated radioactive waste could not remain at McMurdo due to the internationally agreed upon Antarctic Treaty which prevents both nuclear weapons testing as well as nuclear waste dumping in the Antarctic.  As such, a large-scale effort was undertaken to remove the reactor components, buildings, and contaminated soil for a total of 365 metric tons of radioactive waste to the continental United States.  It was later determined that there were indeed cracks in the containment vessel which leaked coolant water into the crushed gravel that had been used as the reactor shield which is what resulted in such a large area of contamination.  As such, more than 9000 cubic meters of contaminated soil was relocated to the continental US.  In total, seven enriched uranium fuel cores were shipped to McMurdo, three of which had yet to be used as the plant was expected to operate for several more years.  The reactor cores, components, and highly radioactive gravel that was used to shield the reactor were shipped to the Department of Energy Savannah River Plant in South Carolina.  The remaining low-level contaminated soil was shipped to the Naval base at Port Hueneme, California.  The clean up operation lasted until 1979 as work on the site could be performed only during the austral summer. 
As a result of the multiple malfunctions of the PM-3A as well as it's clean up activities, there have been concerns that the health of personnel involved with the reactor may have been adversely affected.  Although members of the Navy Nuclear Propulsion Unit were continuously monitored for radiation, many of the military support crew were not.  As such, a study was undertaken by the Department of Defense to estimate an upper bound on radiation exposure for these individuals based on the worst cases of the available data from McMurdo.  Levels of radioactivity in the water were monitored once the PM-3A was used in the production of drinking water.  During the first few years of fresh water production (between 1967 and 1969) there were several instances of abnormally high amounts of tritium in the drinking water.  In addition, there was a case of abnormally high amounts of long-lived beta activity in the drinking water in 1969. 
|Fig. 5: Plaque commemorating the nuclear power facility at McMurdo. (Source: Wikimedia Commons)|
In addition to problems with the drinking water and environmental contamination, there were several recorded instances of crew radiation exposure, some resulting in injury.  During the plant operation, 223 reports of abnormal levels of radiation were recorded.  Of these cases, 14 resulted in injury and 123 resulted in exposure in the amount of 0.350 rem over a period of 7 days.  This is a substantial amount of radiation when it is estimated that, one average, a typical yearly dose from background sources is 0.240 rem.  The remaining 86 instances were abnormal radiation levels detected within the plant and its immediate surroundings.  The conclusion was that a support member would have received a maximum dose of 0.2 to 0.6 rem to the thyroid or 0.2 to 0.5 rem to the red bone marrow per austral summer tour.  The upper bound here is equivalent a typical radiation dosage received by a person living in the United States from typical background radiation and medical procedures.  It is, however, recognized that there were personnel who may have been exposed to radiation outside the confines of factors and data considered in those figures that may be eligible for compensation.  In addition, the estimated dose above does not include members who were part of the decommissioning procedures who may have inhaled or ingested contaminated particles. 
The nuclear reactor installed at McMurdo Station was the first and only to operate on the Antarctic continent. It operated for 10 years and greatly reduced the need for fossil fuels in the Antarctic. Although it was initially thought to be a cost saving device, its unreliability, large operational crew, and large clean up proved it to be an expensive experiment. As a memorial, a plaque now stands at the site of the nuclear power station in McMurdo commemorating the people and services of the PM-3A.
© Tyler Reid. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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