Quarterly report of Ibaraki environmental radiation monitoring, Oct-Dec 1999

The monitoring stations and posts in the circumstances on JCO observed about ten times value as many as the ordinary space gamma dose rate from September 30 to October 1, depend on JCO accident. However, the monthly average value was less than the upper limit of width of variability. The radioactive product was not found in the environmental samples (air dust, fall out and rainwater). The radioactive concentration in the off gas (except rare gas and radioactive iodine in the JCO conversion test facility) and wastewater was less than the emission standard. The emission dose of rare gas and radioactive iodine by JCO accident, September 30, might be 1.6 x 1014 Bq and 1.3 x 1010 Bq, respectively. It might be about 0.1 mSv exposure dose depend on radioactive products in the environment. These above results proved the radioactive concentration in the environment was out of question, although the gamma doses rate increased for a time. (S.Y.)