Yamamoto M, Ishiguro T, Tazaki K, Komura K, Ueno K
Low Level Radioactivity Laboratory, Kanazawa University, Tatsunokuchi, Japan.
Health Phys. 1996 May;70(5):744-8. doi: 10.1097/00004032-199605000-00019.
The alpha radioactive components in the Hemp-palm of Bontenchiku were determined with emphasis on the measurement low-level 237Np by alpha-ray spectrometry after chemical separation. Bontenchiku is a kind of fishing gear for long-line fishing used by the Fifth Fukuryu-Maru (Lucky Dragon). This gear was exposed to fallout from the second thermonuclear test explosion (Bravo) at Bikini Atoll in March 1954. The 237Np content in the Bontenchiku sample was determined to be 11.5 +/- 0.8 mBq g(-1), with an activity ratio of 237Np:239,240Pu and an atom ratio of 237Np:239Pu estimated to be (2.2 +/- 0.2) x 10(-3) and 0.42 +/- 0.04, respectively. The data showed the existence of a chain reaction of 238U and its ratio to be 237Np:239Pu, as well as the presence of 237U at the time of fallout from Bravo event in March 1954.
对本天竹（Bontenchiku）棕榈叶中的α放射性成分进行了测定，重点是通过化学分离后用α射线光谱法测量低水平的237Np。本天竹是第五福龙丸（幸运龙号）使用的一种延绳钓渔具。该渔具于1954年3月在比基尼环礁遭受了第二次热核试验爆炸（布拉沃）的沉降物污染。本天竹样品中的237Np含量测定为11.5±0.8 mBq g(-1)，237Np与239,240Pu的活度比以及237Np与239Pu的原子比估计分别为(2.2±0.2)×10(-3)和0.42±0.04。数据显示了238U的链式反应的存在及其与237Np:239Pu的比例，以及1954年3月布拉沃事件沉降时237U的存在。
