Investigation on present state of radiation protection of a 60Co irradiation facility / 中华放射医学与防护杂志

ABSTRACT

Objective:To explore the present state of radiation protection in an operational large-sized irradiation facility and the distribution of incurred radiation doses in the controlled area under abnormal conditions, and to analyze the acompanied radiation risk.Methods:With an irradiation facility in operation as the research object, the radiation doses were measured using AT1121 X and gamma dose rate meters for the soruce both in working and storage. Thermoluminescent dosimeters (TLDs) were used to measure the dose distribution in an irradiation field under abnormal conditions. The radiation safety features were checked against the several relevant national standards, with the radiation risks evaluated.Results:The radiation dose rates were in the range of 0.09-0.11 μSv/h, lower than the environmental background level whether in storage or working. Under abnormal working conditions, the radiation dose values from high to low were 1.0-101.3 Sv, 32.7-514.0 mSv and 8.7-183.2 μSv in the irradiation field, respectively. At the outside maze, the doses were close to the background level.Conclusions:The protection features of the irradiation facility meet the requirements of the relevant national standards. Under abnormal conditions, radiation could cause serious damages to the persons staying in the irradiation field. These persons were suggested to access to maze as soon as possible to reduce the exposure time, and activate the emergency protection equipments to deescalate the 60Co source onto the well.