237Np in hemp-palm leaves of Bontenchiku for fishing gear used by the Fifth Fukuryu-Maru: 40 years after "Bravo".
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.
Yamamoto
M
M
Low Level Radioactivity Laboratory, Kanazawa University, Tatsunokuchi, Japan.
Ishiguro
T
T
Tazaki
K
K
Komura
K
K
Ueno
K
K
D009405:Neptunium / Q000032:analysis*; D009689:Nuclear Warfare; D010944:Plants; D011847:Radioactive Fallout / Q000032:analysis*
D011847:Radioactive Fallout; D009405:Neptunium