909. 京大炉(KUR)の気中における放射能の動態およびインパクト評価

Recently there has been increased concern over the exposures not only in the radiation environment resulting from activities of human beings but also in natural radiation environment. So this paper presents a study on the spatial distributions and variation both for the induced radioactive gases, especially 41Ar and airborne radioactive dust in the Kyoto University Reactor, Research Institute (KURRI).The amount of 41Ar gas released from the KUR has been decreased by about one-tenth within past seven years due mainly to minimize leakage of the gas from the reactor core installations and further efforts have been focused on decreasing the released radioactivity according to the concept of ALARA.The simultaneity of the diurnal variation in the concentration of airborne radioactive dust observed in several buildings at the KURRI indicated that the changes were not induced by the activities of man.The comparison showed that the exposure dose equivalent rate on workers by radon progenies was high as much as ca. five fold than that caused by 41Ar when the ventilation was not operated in the building, and the annual dose equivalent by radon progenies on the public is also greater by the order of about 3 than that by 41Ar released from the KUR.