Beta-particle response of the Three Mile Island personal dosimeter

Due to the special needs of Three Mile Island (TMI) to monitor personnel for irradiation from beta-particle emitters of various energies, a standard Panasonic UD-802 Personnel Dosimeter was modified to enhance its response within the energy range from thallium-204 (anti E/sub #betta#/ = 0.267 MeV) through yttrium-90 (anti E/sub #betta#/ = 2.28 MeV). The theory behind this modification and the initial calibration of the dosimeter are presented. The algorithm used to compute shallow and deep dose equivalents are shown with emphasis on the beta plus gamma portion of the algorithm. Test results are shown which demonstrate the performance of the dosimetry system for irradiations to thallium-204, strontium/yttrium-90, cesium-137, and extreme mixtures (20:1) of these radiations. These results demonstrate the ability of the modified UD-802 to provide accurate measurements of dose equivalent for beta-particle emitters of various energies in the range from thallium-204 through strontium/yttrium-90