Investigation of radioactivities following the 18th nuclear explosion in China

Investigation of radioactivities for the period of January 26, 1976 and February 4, 1976, following the nuclear explosion in China. The explosion was made on January 23 at 1.00 a.m. EST. Concentration of radioactivities in floating dust at high altitude was normal values. Spatial doses measured at monitoring posts were normal. Radioactivities in rain water and dust were also measured and the value of concentration observed at Hachijo-shima on January 26 was large and 56 pCi/ml. The values after January 29 were large at all measuring stations in Japan. Concentrations in floating dust were a little large and returned to the normal values after February 6. Radioactivities in fall-out were normal. Concentration of I-131 in milk was 113 pCi/l in Ishikawa prefecture. Results of nuclide analysis show that fall-outs include I-131, 132, 133, Ru-103, Ba-140, La-140, Tc-99, Mo-99, and Ce-141. The level of radioactivities observed was lower than the temporary standard. (Kato, T.)