Proficiency testing feasibility study for the measurement of gamma-emitting clearance samples

A proficiency testing feasibility study program was proposed by the National Radiation Standard Laboratory (NRSL) of Taiwan to understand the capabilities of laboratories dealing with clearance measurements, and to issue related technical criteria for radioactive waste assay. In this program, twelve blind test samples with different levels of radioactivity, radionuclides and different packing densities were prepared. Seven laboratories participated in this program and fourteen instruments were tested. Participants were required to report their raw data to NRSL, which would evaluate the effects of the background, geometry and the packing density to obtain the final results of the participants. In this study, the typical uncertainties of the participants were around 24%, and about 70% of the measured results produced En values, which were smaller than one.