Estimation of amount of released radioactivities and exposure dose equivalents of workers and the public due to the fire and explosion incident at the bituminization demonstration facility

not registered; Noda, Kimio; not registered  ; not registered; not registered; not registered; not registered

On the fire and explosion incident at the bituminization demonstration facility on March 11, 1997, thirty-seven workers were internally exposed due to activity leakage from the filling room. Maximum committed effective dose equivalent from internal exposure was estimated and found to be approximately 0.4 to 1.6 mSv based on the results of whole body counting and nuclides analysis of nose-smear samples and air-sampler filters. Maximum effective dose equivalent from external exposure was estimated and found to be approximately 4SV. The explosion broke many windows and shutters of the facility and the radioactive material was released from the openings to outside. Radionuclides of Cs, Sr, Pu, and Am were detected by the environment monitoring within the site. In Oarai site (about 20 km away from the facility), a little amount of Cs radionuclides were detected from the air-dust sample. Some soot within the facility was sampled and radionuclides were analyzed. Based on the above information, the amount of released activities by the incident was evaluated and found to be approximately 1 to 4 GBq activity (principally Cs with 10% Cs excluding C) and 610910 GBq activity. Maximum committed effective dose equivalent to the public by the above amount of activity release was evaluated and found to be approximately 110 to 2 10 mSv.