Unprecedented Exposition to Radiation

Six years after it had suffered from the severe accident in First Fukushima Nuclear Power Plant, Japan experienced another unprecedented accident of major leak of radiation. Four staffs in Oarai Research and Development Center of Japan Atomic Energy Agency inhaled radioactive materials leaked from storage case for uranium and plutonium on Wednesday. The level of radiation they were exposed was something unprecedented in the country.

The accident happened in a building for studying new type of fuels. When the staffs opened the cap of the tank, which contained nuclear fuels, plastic sheet wrapping the fuels suddenly bursted and powder of radioactive materials was splashed. Although the staffs were guarding their nose and mouth with special mask against radioactive materials, they inhaled certain amount of radiation through it.

JAEA announced that it detected 22,000 Bq of plutonium from the lung of one of those four staffs. It was the level paralleled with 1.2 Sv of annual exposition to radiation, which was unprecedentedly high in Japan. Other three staffs were also exposed to radiation inside their body, which level was lesser than the first one. There is another person who has possibly been exposed.

JAEA contained uranium and plutonium in the case in 1991. While their staffs checked the situation every year, they had never opened the case. Because they did not have any idea of possible burst of the plastic sheet, the check on Wednesday was done without necessary measure for containing radiation. Chairman of Nuclear Regulation Authority, Shun-ichi Tanaka, warned JAEA to be careful in dealing with nuclear materials and required the board members to have serious reviews.

Influence of radiation on human body will not be seen immediately. Plutonium is sent to liver or bones through artery and causes cancer while it is stocked. The likeliness of suffering cancer gets high with 100 mSv. The man with worst exposure inhaled radiation ten times higher than the level. The staffs need to be under close watch by medical doctors.

Nuclear policy of Japanese government is losing its credibility. The government decided to abolish a high-speed breeding reactor named Monju in Tsugura, Fukui. One resident of Tsuruga City told that she were concerning whether JAEA could dismantle Monju in a safe manner. It is also concerned whether the government will make serious review on the accident in Oarai.