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Mayak Chemical Combine is located near Ozersk, a closed city in the Southern Urals. Until 1992 the city was known only by its post office box number Chelyabinsk-65, and prior to 1990, as Chelyabinsk 40. The city is situated approximately 15 km east of the city of Kyshtym and about 70 km north of Chelyabinsk, a city with a population of about one million people in the Asian part of Russia. The reactor area is located about 10 km from Ozersk, a city with a population of 85 600. Construction of the Mayak Chemical Combine (MCC) began in November 1945, and the first reactor became operational in June 1948. Seventy thousand inmates from 12 different work camps laboured in the construction of Mayak's different facilities. The complex itself covers an area of approximately 90 km2 and employs 17 100 people. There used to be six operational reactors at Mayak Chemical Combine (MCC) for the production of weapons plutonium. Of these, five were graphite-moderated while the sixth was originally a heavy water reactor. These reactors have now been shut down. The heavy water reactor was later modified to a light water reactor which remains in operation today. An additional light water reactor produces isotopes for civilian use. There is a reprocessing facility (RT-1) in use at Mayak, a vitrification facility for liquid waste and about 100 storage tanks containing high level radioactive waste. The five water-cooled, graphite-moderated reactors at the Mayak Chemical Combine are located at two separate areas along the south-eastern bank of Lake Kyzyltash. All of the production reactors utilise an open cooling cycle whereby water from the lake is pumped directly through the reactor core and out again into the lakes. The temperature of the discharge water was about 70ºC. The A, IR and AV-1 reactors are located at Plant 156, whereas the AV-2 and AV-3 reactors are located in a different area within the complex. The A Reactor The first reactor, the A reactor, was a graphite-moderated production reactor. It had 1 168 channels with natural uranium enclosed within vertical aluminium tubes, and these were designed to operate at 100 MWt, but this thermal effect was later upgraded to 500 MWt. The core was 9.2 m high and 9.4 m in diameter. The top of the reactor was 9.3 m beneath the ground. Cement walls 3 m thick were built around the reactor, and these in turn were surrounded by large water tanks. The reactor was completed in 1948, only 18 months after the initial start of construction. The reactor was loaded with all the available uranium in the Soviet Union and began operation on June 19, 1948. The plutonium produced here was used in the first Soviet atom bomb which was tested at Semipalatinsk on August 29, 1949. The reactor was operational for 39 years, and was finally shut down in 1987. It is housed in Building 1 at Plant 156. The dismantling of the reactor is being carried out in three stages. During the first stage, the reactor was shut down and its fuel unloaded. The second stage, which is now in progress, entails the removal of the control and operating systems and filling the remaining empty spaces with cement. This procedure is expected to take about five years. The final stage, which is expected to take 20 to 25 years, will be a 'waiting period' until a decision is made to either bury the reactor on site or remove it altogether. The IR Reactor The IR reactor was used for the production of plutonium and to test the fuel of both the A-reactor and the RBMK reactors. Housed inside Building 701 near the A-reactor, the IR-reactor is a small graphite-moderated 65 MWt reactor with 248 channels. Construction of the reactor began on August 15, 1950, and it became operational December 22, 1951. The reactor was shut down after 36 years of operation on May 24, 1987. The AV-1, AV-2, and AV-3 Reactors The three large graphite-moderated production reactors AV-1, AV-2, and AV-3 probably all share the same design. Each has 2 001 channels. Of the three reactors, only the AV-2 reactor has been described in openly available literature. The core of the AV-2 reactor consists of a vertical cylinder 7.6 m high and 11.8 m in diameter. Radiological shielding is provided in that the active zone is protected by three layers. The first layer consists of sand and water 1.5 m thick and a 2 m thick concrete wall. On top of this is a 1.5 m thick layer consisting of a mixture of sand and bathite ore covered by a further layer of concrete 3 m thick. Finally there is a pool of water 1.5 m deep. AV-1 went into operation in 1955 and was shut down on August 12, 1989; AV-2 came on line in April 1951 and shut down in July 1990. AV-3 started up on September 15, 1952, and ceased operations on November 1, 1990. The AV-3 reactor is housed in Building 501 at Plant 156, and was the last of the five graphite reactors to be shut down. "Ruslan" The second reactor to be started at Mayak Chemical Combine was a heavy water moderated reactor known as "Ruslan". This reactor went into operation some time between the end of 1948 and 1951, and was active until about 1980. Towards the end of the 1980s, it was rebuilt to a light water reactor with a capacity of 1 000 MW. "Ruslan" is used to produce tritium for the Soviet hydrogen bombs and specific isotopes such as 238Pu. "Lyudmila" Another type of reactor which is still in use at Mayak is a light water reactor called "Lyudmila". Its power is 1 000 MW and this reactor is also used for the production of tritium and various other isotopes, including 238Pu. Total Plutonium Production at Mayak Chemical Combine Between the five graphite-moderated reactors at Mayak, a total of 58.3 tonnes of plutonium has been produced. Up until the end of 1992, the two remaining reactors are believed to have produced 14.7 tonnes, for a total plutonium production at Mayak Chemical Combine of 73 tonnes. Source: Bellona Foundation, http://www.bellona.no/imaker?sub=1&id=8223