Construction of the 5 MWe experimental reactor began in 1980, and the reactor first went critical in 1986. This reactor was an initial small technology proving reactor for a following development program of larger Magnox reactors. The spent nuclear fuel reprocessing facility appeared to still be under construction in 1992. The 5 MWe experimental reactor operated intermittently until 1994 when it was shut down in accordance with the U.S.-North Korea Agreed Framework. Following the breakdown of the Agreed Framework in 2002, operation restarted in February 2003, creating plutonium within its fuel load at a rate of about 6 kg per year. The reactor fuel was replaced between April and June 2005. The spent nuclear fuel has been reprocessed with an estimated yield of about 24 to 42 kg of plutonium metal, some of which was used for the nuclear weapons involved in the 2006 and 2009 North Korean nuclear tests.