Radiochemical Analysis of "Bikini Ashes" fallen on Board the No.5 Fukuryu Maru on March 1, 1954.

Abstract

In order to find the proper method of medical treatment for the afflicted men on board the No.5 Fukuryu Maru on March 1, 1954, it was necessary to know the species and amounts of radioactive elements in the dust of the so-called Bikini Ashes which had fallen on board.At the request of the Hospital of Tokyo University, the authors started analyses on March 18.A combined method of chemical separation with the use of carriers and separation with the use of ion exchange resin was applied;17 nuclides were detected and the results of quantitative estimation of alkaline earth metals were reported on March 31.The main constituent of the ashes was found to be calcium hydroxide and its radioactivity was 0.37mC/g (April 23) which was decayed proportionally to -1.37 power of the time elapsed.The chemical group separation was carried out as shown in Table 3; the second, third(especially rare earth metals)and fifth(alkaline earth metals)analytical groups showed strong radioactivity.By ion exchange method(Fig. 4), the fraction of anions, Zr and Nb fraction, U fraction, the fraction of rare earth metals and the fraction of alkaline earth metals were separated.Furthermore, each constituent of those fractions was estimated quantitatively.In order to confirm the presence of 129mTe, 129Te, 131I, 132I, 103Rn, 106Ru, 106Rh, 95Zr and 95Nb, the chemical method was used.The members of alkaline earth metals, e.g.45Ca, 89Sr, 90Sr, (90Y), 140Ba and (140La), and the members of rare earth metals, e.g.91Y, 141Ce, 143Pr, 144Ce, 144Pr and 147Nd were estimated after the separation with the use of ion exchange resin.The presence of 237U was confirmed from its radioactivity and chemical properties.Also α-tracks of 239Pu.were detected by autoradiograph ic method.Table 6 indicates the summary of the results.