Estimation of surface anthropogenic radioactivity concentrations from NaI(Tl) pulse-height distribution observed at monitoring station

A method of estimating surface radioactivity concentrations of key anthropogenic radionuclides from NaI(Tl) pulse-height distribution observed at a monitoring station (MS) was discussed. In the estimation, a realistic assumption on geometric distribution of source and obstacles around the detector o...

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Bibliographic Details
Published in:Radiation protection dosimetry 2015-04, Vol.164 (3), p.304-315
Main Authors: Hirouchi, J, Yamazawa, H, Hirao, S, Moriizumi, J
Format: Article
Language:English
Subjects:
Cesium Radioisotopes - analysis
Gamma Rays
Humans
Iodides - analysis
Photons
Regression Analysis
Sodium - analysis
Spectrometry, Gamma - methods
Thallium - analysis
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Summary:A method of estimating surface radioactivity concentrations of key anthropogenic radionuclides from NaI(Tl) pulse-height distribution observed at a monitoring station (MS) was discussed. In the estimation, a realistic assumption on geometric distribution of source and obstacles around the detector of the MS including the infiltration of radionuclides into the ground was used and the results were compared with ones with a commonly used assumption of a uniformly distributed plane source. The surface radioactivity concentration was determined by comparing the count rates at the full-energy peak ranges between observation and calculation with an electron-photon transport code EGS5. It was shown that the estimated absolute values of concentration differed by a factor of ∼1.5 depending on the assumption of infiltration depth. The estimated surface concentrations of (131)I, (134)Cs and (137)Cs were in good agreement with ones determined by the in situ measurements with an HPGe detector and the cumulative values of daily surface depositions.
ISSN:0144-8420
1742-3406
DOI:10.1093/rpd/ncu305