Analysis of radiation exposure factors as seen in individual dose

In the Tokyo Metropolitan Isotope Research Center, radiation workers and the persons entering radiation-controlled areas are monitored with FBs and TLDs for radiation exposure. The records of such monitoring with TLDs (thermoluminescence dosimeter) for seven years from fiscal 1977 have been examined. The purpose was to analyze the factors contributing to the radiation dose in individuals, as the effort to lower individual exposure in the TMIRC. (1) Exposure was relatively large in the personnel of the Safety Section. (2) A major factor for this was that the personnel has handled small sealed radiation sources frequently, as compared with the personnel in other sections. (3) There was seasonal variation in radiation exposure, and the exposure tended to concentrate in the latter half of each fiscal year. (4) Whether to handle large sealed radiation sources and radiation generators and the class of controlled areas did not much contribute to the amount of exposure. (Mori, K.)