A Mobile Whole-Body Counter for Accidental and Occupational Monitoring of Internal Contamination

The present work describes the construction and optimisation of parameters of a mobile whole-body counter (MWBC). The counter employs a 12.5 cm X 12.5 cm scintillation Nal (T1) crystal from Nuclear Enterprises. The optimising of the detector shielding as well as the shielding of the human subject is achieved with respect to background reduction, sensitivity and the portability of the counter. The counter is mounted in a Czechoslovak made vehicle type Praga V3S and should be considered as a convenient and reliable instrument for accident monitoring and monitoring of workers with open radioactive sources. The minimum detectable amount (MDA) of 137 Cs for 10 min measuring time and the 95% confidence level is about 450 Bq.