Calibration of environmental and personal dosimeters by submersion in and distance exposure to 133Xe

After the accident at Three Mile Island Nuclear Power Plant, Radiation Management Corporation was asked to assist with the emergency environmental monitoring program around the plant. The dosimeters are relatively new designs from Panasonic and use lithium borate (Li2B4O7:Cu) and calcium sulphate (CaSO4;Tm) phosphors. They had been calibrated previously to 60Co. Since the plant was releasing substantial amounts of 133Xe, it was necessary to calibrate these dosimeters for this radionuclide. It was determined that for Panasonic personal dosimeters submerged in an infinite cloud of 133Xe, the correction factors are approx. 20 for the shallow dose equivalent and 0.11 for the deep dose equivalent. For personal dosimeters exposed to the 81 keV γ-rays of 133Xe, the correction factor for both depths is approx. 1.45. For Panasonic environmental dosimeters submerged in an infinite cloud of 133Xe, the correction factor is approx. 0.05 for the deep dose equivalent. If these environmental dosimeters are exposed only to the 81 keV γ-rays of 133Xe, the correction factor for the deep dose equivalent is approx. 1.84. (author)