A Becquerel/Sievert (BS) survey meter was conceptually developed. The BS survey meter can be used easily, like conventional radiation survey meters, to measure radioactivity and radiation dose simultaneously. Simulation of radioactivity measurement by using the BS survey meter was conducted using a model of Cs–137 circular surface contamination. As a result, the radioactivity of Cs–137 measured using the BS survey meter was underestimated. The cause of the underestimation was determined, and an inequality in the upper and lower limits of radioactivity was derived. These results indicate that the upper and lower limits of radioactivity could be used as operational measurands with the BS survey meter.

 The purpose of this study was to evaluate the measurement accuracy of a simple γ–ray scintillation survey meter by conducting basic investigations (reproducibility, energy characteristics, influence of β–rays, etc.). We evaluated the performance of the simplified survey meter by using three types of scintillation survey meters for γ–rays and compared it with an energy-compensation type scintillation survey meter for γ–rays. As a result, it was found that the simplified survey meter may underestimate or overestimate the energy of γ–rays, or the energy of γ–rays to be measured may be out of range, depending on the conditions of use.