Police on Wednesday arrested six former executives and current employees of JCO Co. on suspicion of professional negligence resulting in death in connection with the nation's worst-ever nuclear power accident last year in Tokai, Ibaraki Prefecture.
Those arrested included Kenzo Koshijima, 54, head of the plant at the time of the accident; Hiromasa Kato, 61, then chief of the production department; and Yutaka Yokokawa, 55, who was exposed to radiation in the accident along with two other workers who later died -- Hisashi Ouchi and Masato Shinohara.
The six have reportedly admitted the police charges brought against them.
Police suspect that systematic violations at JCO -- such as inadequate safety training and illegal operations -- were to blame for the accident, which occurred at the firm's nuclear fuel processing plant in the village of Tokai, some 120 km northeast of Tokyo, on Sept. 30, 1999.