ICRP International

Conference on Recovery After Nuclear Accidents

Radiological Protection Lessons
from Fukushima and Beyond

December 1 - 18, 2020

A. Mishra, R. Khanal

Updated: Dec 11, 2020

Assessment of 137Cs in the Environment of Hetauda, Nepal by In-situ Gamma Ray Spectrometry

A. Mishra, R. Khanal (Tribhuvan University, Nepal)

The fallout from nuclear weapon testing, Chernobyl disaster and Fukushima accident have spread considerable amount of 137Cs in the atmosphere which ultimately gets deposited on the earth surface. The radiological mapping of 137Cs is important due to its longevity after deposition as it has longer half-lives. The aim of this study is to assess the radioactive deposition of 137Cs in ground for the establishment of base line data of the distribution of 137Cs in the environment of Hetauda. For this purpose, in-situ monitoring is performed using portable (backpack) gamma ray spectrometer with NaI(Tl) detector of 0.347 liters. The surface activity was found to lie in the range 0.003 to 2.382 kBq/m2 with an average of 0.581±0.343 kBq/m2.The study provides that the spatial variability of the 137Cs is low in the area. The data can be useful for tracing soil erosion in the area.


A. Mishra, R. Khanal (Tribhuvan University, Nepal)

核兵器試験、チェルノブイリ災害、及び福島事故による放射性降下物は相当量の137Csを大気中に拡散させ、137Csが最終的に地表に堆積している。137Csは半減期が比較的長く堆積後も長寿命であるため、放射線マッピングが重要である。本研究の目的は、ヘトウラの環境での137Cs分布に関する基準データを作成すべく137Csの地表での放射能堆積を評価することである。このため0.347リットルのNaI(Tl)検出器を搭載した可搬型(バックパック)ガンマ線分光計を用いて原位置監視を実施する。地表の放射能は0.003~2.382 kBq/m2の範囲で平均0.581 ± 0.343 kBq/m2にあることが明らかとなった。本研究はこの地域での137Csの空間的ばらつきが小さいことを示している。このデータはこの地域で土壌侵食を追跡するのに役立つ。

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