Introduction of optically stimulated luminescence based postal audits for radiation protection level dosimetry at Secondary Standard Dosimetry Laboratories

The OSLDs demonstrated acceptable reading reproducibility of 1.75% and a signal depletion of 0.25% per readout. The OSLDs signal fading resulted in a signal decrease of 2.1% in the period from eight days to over 160 days post irradiation. A relative expanded (k = 2) uncertainty of the OSLD determined air kerma was estimated to 3.08%. In two audit runs in 2015-2016, 29 SSDLs participated. The average ratio of the air kerma measured by the IAEA to the air kerma stated by the SSDL was 0.998 and the standard deviation of the distribution of results was 1.8%. All participants except one had results within the acceptance limits of ±7%. One laboratory with the result outside the acceptance limit was invited to a follow-up procedure with the aim to resolve the discrepancy.