Determination of fallout nuclides by the 19th Chinese nuclear explosion test.

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This paper describes analysis of the fallout from the 19th Chinese nuclear explosion test. (1) The analysis identified the following 16 nuclides using the radioactive decay method : 95Zr, 95Nb, 97Zr, 97Nb, 99Mo, 99mTc, 131I, 132Te, 132I, 133I, 137Cs, 140La, 143Ce, 147Nd, 237U and 239Np. (2) Assessment of a baby's thyroid dose by radioiodine based on this nuclear explosion test was carried out. Culculated dose is 4.5 mrem/yr which is nearly one-third of radioiodine release guideline for a light-water-cooled nuclear powerstation. (3) Nuclide concentration, (number of nuclides)/(nuclear fission yield), going back to predicted fission time was calculated. Assuming the fast fission of 239Pu, the con-centration curves of each nuclide crossed at approximately the same point. The reported fission time by ERDA of U.S.A. fell into the authors' speculated fission time region which was calculated from the time dependent nuclide concentration curves mentioned above. (4) The 237U was identified from the decay curves of 239Np photopeak (278 keV) and of multiplet of 239Np and 237U (207 keV). The estimated atomic ratio of 239Np: 237U at fission time was 28: 1.
一般社団法人日本原子力学会の論文