Intercomparison of Spanish environmental dosimetry services at 137Cs energy

According to its annual plan for inter-comparison exercises, the Spanish regulatory body (Nuclear Safety Council, CSN) organized in 2007, in collaboration with CIEMAT, the third national inter-laboratory comparison test among the services of environmental dosimetry in Spain. The radiological quantity used was the ambient dose equivalent, H*(10). Different values of this quantity were assigned to each laboratory. These values ranged between 210 and 390 μSv. All dosimeters were exposed at the same air kerma rate level and practically at the same distance from the source. H*(10) was estimated following the procedures for area and portable meters described by the International Organization for Standardization (ISO) in the ISO 4037-3 document. Conventionally, an environmental dosimeter calibrated in units of ambient dose equivalent is used to estimate the limiting quantities of ICRP. However, this is at the end the same objective than that of a personal dosimeter. Therefore, we can use the same evaluation procedure for both the environmental and the personal dosimeters. The analysis of results was carried out following two procedures: firstly, by comparison with the criteria established in the new ANSI 13.11 standard (2001 version) and second, by analysis of the 'trumpet curves'. This paper presents the results obtained by the seven laboratories (two of them contributing with two different dosimetry systems) included in the study, which participated on a voluntary basis, all of them using different thermoluminescent detectors and dosimetric units. All results are in full agreement with the evaluation procedures, lying within the tolerance limits fixed by the trumpet curves and satisfying the Q<0.4 requirement established by the mentioned ANSI 13.11-2001 standard. (author)