Identified as a special talent at the age of 7, Kim was fast-tracked into the Bungang High School and, after the intervention of Kim Jong-Il, was sent abroad to study nuclear physics at the age of 13. Given a personal tutor at Kim Il Sung University in Pyongyang, he received his master's degree at the age of 19 and a doctorate at 21, according to a defector from the North who worked under him.