Methods for the experimental study of 220 Rn homogeneity in calibration chambers.

Autor: Mitev K; Sofia University 'St. Kliment Ohridski', Faculty of Physics, 1164, Sofia, Bulgaria. Electronic address: kmitev@phys.uni-sofia.bg., Cassette P; CEA, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), 91191, Gif-sur-Yvette Cedex, France., Pressyanov D; Sofia University 'St. Kliment Ohridski', Faculty of Physics, 1164, Sofia, Bulgaria., Georgiev S; Sofia University 'St. Kliment Ohridski', Faculty of Physics, 1164, Sofia, Bulgaria., Dutsov C; Sofia University 'St. Kliment Ohridski', Faculty of Physics, 1164, Sofia, Bulgaria., Michielsen N; Institut de Radioprotection et de Sûreté Nucléaire (IRSN), 92262, Fontenay Aux Roses, France., Sabot B; CEA, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), 91191, Gif-sur-Yvette Cedex, France.
Jazyk: angličtina
Zdroj: Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine [Appl Radiat Isot] 2020 Nov; Vol. 165, pp. 109259. Date of Electronic Publication: 2020 Jul 05.
DOI: 10.1016/j.apradiso.2020.109259
Abstrakt: This work presents two experimental methods for the evaluation of 220 Rn homogeneity in calibration chambers. The first method is based on LSC of the 220 Rn decay products captured in silica aerogel. The second method is based on application of solid state nuclear track detectors facing the air of the calibration chambers. The performances of the two methods are evaluated by dedicated experiments. The repeatability of the LSC-based method, estimated as relative standard deviation of the LSC measurements of ten silica aerogel samplers exposed under the same conditions is found to be 1.6%. Both methods are applied to study thoron homogeneity in the commercially available 50 L AlphaGuard emanation and calibration container, which was empty and its fan was turned on. It was found that the 220 Rn distribution in this case is homogeneous within 10%. Both methods are also applied to test the thoron homogeneity in the BACCARA chamber at IRSN during a thoron calibration exercise. The results show that, at the centre of the chamber where the inputs of the sampling systems of the radon/thoron detectors were put close to each other, the thoron inhomogeneity is less than 10%. However, regions of higher thoron concentrations are clearly identified near the walls and the upper part of the chamber, with 220 Rn concentrations being up to 60% higher compared to the concentration at the reference point. These results highlight the importance of the control and assessment of thoron homogeneity in thoron calibrations and in the cases when radon monitors are checked for thoron influence.
(Copyright © 2020 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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