INES-event
INES 2

RADIATION EXPOSURE OF WORKERS AT TOKAI REPROCESSING PLANT

Four workers were exposed internally while they were replacing a filter element of the vacuum filter installed in the sampling system connected to the plutonium receiving vessel of the rework process of the Tokai Reprocessing Plant on December 27, 1993. At the time of incident, operation of the Tokai Reprocessing Plant was stopped for routine maintenance from December 5, 1993. The cause of the internal exposure was that the four workers inhaled plutonium particles dispersed from the filter element in the vacuum distribution room. The floor of vacuum distribution room was contaminated by this radioactive release. The bio-assay analysis results on January 11, 1994, showed that the maximum estimated internal exposure over 50 years was 90 mSv of effective dose equivalent and 1700 mSv of tissue dose equivalent for one of the 4 workers. Both dose equivalents exceeded the legal dose limit (50 mSv/y and 500 mSv/y), respectively.
The rating of this event is classified at level 2 under the on-site impact criterion.

Location: TOKAI REPROCESSING PLANT
Event date: Mon, 27-12-1993
Nuclear event report
Legenda & explanation