Alpha survey instruments

Los Alamos National Laboratory and Pacific Northwest Laboratory tested alpha radiation survey instruments for the Department of Defense. Five models were evaluated for their ability to detect radiation, susceptibility to mechanical stress, sensitivity to radio-frequency and other environmental factors, and field performance. This paper concentrates on the field-testing phase of this evaluation, which was designed to measure the hot spot detection frequency of competing models under realistic survey conditions when used by surveyors with a broad spectrum of experience. The data were analyzed to determine alpha source activity for a 50% detection frequency. This is the source activity that is detected 50% of the time under survey conditions. The results show that none of the models tested reliably detect spot activities below about 500 disintegrations per minute (dpm) and support the conclusion that these models are not suitable for verifying compliance with transuranic release limits of 100 or 300 dpm/100cm2. The implications of this finding are discussed