Online ISSN: 1884-4111 Print ISSN: 0033-8303
Radioisotopes 66(1): 11-20 (2017)

技術報告Technical Report

野菜(ズイキ)で作る自然放射能線源と教育利用の可能性Natural Radiation Sources Fabricated from the Zuiki Taro Plant and Potential for Educational Use

1株式会社日本遮蔽技研Japan Shield Technical Research Co.,Ltd. ◇ 963–8041 福島県郡山市富田町字権現林11 ◇ 11 Gongen-bayashi, Tomita, Koriyama, Fukushima Pref. 963–8041, Japan

2株式会社日本環境調査研究所Japan Environment Research Co., Ltd. ◇ 342–0008 埼玉県吉川市旭8–3 ◇ 8–3 Asahi, Yoshikawa, Saitama Pref. 342–0008, Japan

受付日:2016年8月4日Received: August 4, 2016
受理日:2016年9月13日Accepted: September 13, 2016
発行日:2017年1月15日Published: January 15, 2017

天然核種40Kを含むズイキの葉柄部の皮をはぎ,乾燥,粉末化して,圧縮成形法を適用した。でき上がったディスク状ズイキ線源10個の重量,直径,厚さ,1分間計数(GMサーベイメータで主に40K由来のβ線を測定)の平均値(標準偏差)は15.1(0.03) g, 9.98(0.1) mm, 35.2(0.01) mm, 163.4(10.5) cpmであった。また測定試験により,ズイキ線源は放射線防護の3原則と,放射線計数の統計的変動に関する測定実習に使用できることがわかった。

“Zuiki” is the stem of a taro plant containing natural radioactive potassium-40. Several zuiki stems were peeled, dried, and micronized; then, the compression and formation method was used to make ten disk-shaped sources. These sources were measured as to their weight, thickness, diameter, and radiation count (using a GM-survey meter). The counted radiation was mainly attributed to β-rays from 40K. The averages (SD’s) of the weight, thickness, diameter, and radiation count were 15.1(0.03) g, 9.98(0.1) mm, 35.2(0.01) mm and 163.4(10.5) cpm, respectively. The usability of the sources for educational purposes was examined in three tests on the dependence of the radiation count versus time, distance, and shielding. Furthermore, the statistical fluctuation of the radiation counts was examined by making 50 measurements. It was concluded that the zuiki radiation sources were useful for demonstrating the three principles of radiation protection and the statistical fluctuation of radiation counts.

Key words: taro stem; natural radioisotope; potassium-40; radiation source; radiation education

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