A Portable Field Calibrator for Radiological Survey Instruments Which Operate over the Range from Background to 500 R/Hr

摘要

This report presents the results of a development program leading to the design and production of a prototype all-mechanical portable field calibrator for radiological survey instruments. Utilizing spent uranium as shielding material the calibrator contains a Cesium 137 gamma source of 220 curies. Variation in dose rate is accomplished by means of a series of eight attenuator slides which are also fabricated of uranium. The range of obtainable dose rates is from .4 mr/hr to 1000 r/hr. The radiation beam is directed into a test chamber which is in the form of a 16 inch cube. Instruments to be calibrated are viewed directly through a large lead glass window. The dose rate selector mechanism and interlock system for the access door employ a novel all-mechanical fail-safe design. A set of four probe wells containing Cesium sources is provided for the calibration of dosimeters and instruments which utilize external probes. The unit weighs 1125 pounds; is completely mobile; and requires no external source of power for its operation.