Intercomparison of Luminescence Measurements of Bricks from Dolon' Village: Experimental Methodology and Results of European Study Group

Abstract

Thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques were applied to quartz grains extracted from various depths in bricks taken from buildings in the village of Dolon', Kazakhstan, to determine the cumulative absorbed dose, D_T. The measurements were performed in four laboratories (EU supported Measurement Group). The results obtained using TL and OSL are compared and discussed with reference to known sources of experimental uncertainty and relevant luminescence characteristics that may affect the evaluation of the absorbed dose. The external nature of the irradiation due to gamma rays from artificial radionuclides is verified by the measurement of depth-dose profiles, and these are compared with those obtained in previous studies for bricks from the same region. To produce these profiles, the cumulative dose due to natural background radiation, D_BG, was assessed, particularly based on the concentrations of radionuclides of lithogenic origin within the bricks and the surrounding environment. The consistency of these estimates of D_BG was assessed using depth-dose data and absorbed dose determinations for bricks collected from shielded locations. The values of cumulative absorbed dose since the onset of fallout, D_X, were calculated as the difference between the values of total cumulative dose in bricks since its manufacture, D_T, and values of D_BG. Furthermore, estimations of the cumulative absorbed doses in air in the reference location near the sampled buildings, _RLD_X, were obtained using corresponding conversion factors, C_RL, estimated on the basis of previous work. In addition to results for samples distributed for the International Intercomparison, reference is made to relevant results from samples that were collected in 1999 from Dolon' village and studied as part of EU-supported research.