A large-scale radiation leak at a major nuclear reactor in Japan could kill more than 400,000 people and cost up to 460 trillion yen over 50 years, according to a study by a Kyoto Sangyo University researcher released Monday.

Pak Sung Jun, a full-time lecturer at the university, made the estimate assuming an accident similar to the one in Chernobyl, Ukraine, occurred at a 1,180-mw reactor in Japan such as either the No. 3 or No. 4 pressurized water reactors of the Oi nuclear plant in Fukui Prefecture.

Few estimates have been made on the damage a nuclear accident in Japan would cause since the former Science and Technology Agency's estimate in 1959, made before the government began building nuclear plants on a large scale. The agency came up with a cost of 3.7 trillion yen, experts said.