Low-energy β/ϒ response of personnel frisking instrumentation

There is always a concern for the effects that radiation has on the human body. Any type of contamination, whether it be on the skin or on the clothing, is a potential hazard for workers. Therefore, personnel contamination monitoring (frisking) and the necessary instrumentation are an integral part of any radiation protection program.

Regulations exist to provide the framework for radiation protection programs. Since the work for this thesis was performed at Oak Ridge National Laboratory (ORNL), the Department of Energy supplies the necessary regulations. An evaluation of the frisking instrumentation is needed to determine if the instrumentation can meet the regulatory limits.

At ORNL, a survey of the radiological environment indicated the presence of low-energy β/γ emitting radionuclides, specifically ¹⁴C and ¹²⁵I. The purpose of this thesis is to provide an evaluation of the response of frisking instrumentation to these low-energy emitters.

The efficiencies of selected instruments are determined for various radionuclides, including the low-energy emitters. Statistical procedures are developed which yield density functions for efficiency and activity present. The density functions provide information on how precisely the efficiency and activity can be determined. Point estimates are also calculated for comparison. In addition, the Lower Limit of Detection (LLD) and the effects of geometry on efficiency determination are studied.