Jiji PressTOKYO (Jiji Press) — The Nuclear Regulation Authority said Wednesday it has tentatively rated a radiation exposure accident at a nuclear research facility in Ibaraki Prefecture, northeast of Tokyo, in June as a Level 2 “incident” on the International Nuclear and Radiological Event Scale.
The international scale ranges from zero for no safety significance to Level 7 for a major accident.
In the accident that took place on June 6, a vinyl bag inside a metal container for radioactive materials ruptured during an inspection of nuclear fuel materials at the fuel research wing of the Japan Atomic Energy Agency’s Oarai Research & Development Center, showering the materials on five workers.
Trace amounts of plutonium were detected from all the five workers.
Internal radiation exposure would likely reach 100 millisieverts to less than 200 millisieverts for the one of the five who was most exposed to radiation if the exposure continued for 50 years, exceeding the annual limit of 50 millisieverts.