Nuclear program of North Korea 

Between 1947-1950, the former Soviet Union conducted the uranium geological exploration in North Korea and discovered up to 26 million ton of uranium ore reserve. Among these only 4 million ton were useful for industrial development. 

After the Korean war (1950-1953), the North Korea began to educate specialists in the nuclear research activity. For this purpose the USSR and the DPRK signed an agreement in 1956. Before 90's, about 300 North Korean nuclear specialists were educated in the Soviet institutions, including the Moscow Engineering and Physics Institute, the Bauman Moscow High School of Technology, the Moscow Energy Institute, the Joint Nuclear Research Institute in Dubna.   

In 1959, the DPRK signed two agreements with the USSR and China on cooperation in peaceful use of the nuclear power in Yongbyon. Six years later the research center was built there, and the DPRK received from the USSR the 2 MWe experimental reactor IRT-2000. Later North Koreans upgraded the reactor up to 8 MWe by themselves, but the fuel had been received from the USSR till 1991. 

The USSR also built radiochemical laboratory with in Yongbyon for extracting radioactive isotope, and a 100W critical assembly using the 10% enriched uranium dioxide.

In 1974, the DPRK joined the International Atomic Energy Agency (IAEA) to get access to materials for the nuclear power infrastructure, and at the same time, asked China for assistance in developing the nuclear weapons.   (to be continued)