In 1960s the Soviet Union and its allies in the Eastern Europe began to rush the constructions of many nuclear power stations. This paper clarifies that a rapid growth of nuclear energy production during the following two decades in the “Eastern Block” was needed due to the Soviet Unionʼs serious energy crisis caused by the erroneous choice of energy sources in the national policy, and, meanwhile, the Eastern Germany, Czechoslovakia and other East-European allies were so eager to introduce nuclear energy due to their poverty in quality and quantity of their own energy sources. The Soviet Union exported only light water reactors to its allies, despite it developed nuclear energy with its particular type of graphite reactors domestically. This paper also aims to make clear the overall framework of the light water reactor export from the Soviet Union to its allies in the Eastern Europe, including the organization of a unique nuclear fuel cycle, doubled for both of the graphite reactors and the light water reactors, and the demand pressure on the sole light water reactor manufacturer.