An unusually large amount of strong radioactive ash was produced by the thermonuclear test conducted on March 1954 at the Bikini Atoll in the South Pacific by the United States Atomic Energy Commission. Under such circumstances, to meet the urgent needs of public health, the studies on the radioactivity of Bikini ash and the radioactive contamination of environment have been started, from the health physics standpoint, with the initiative of the author under close cooperation with the public health officers of local governments in Osaka district since the middle of March 4 1954, when the author was the head of the Department of Biophysics, Osaka City University, School of Medicine. The estimation of the probable dose of radiation the might have been received during their dosage and the accurate estimation of beta-ray energies and the detection of alpha-ray activity as well as the identification of various radioactive nuclides included in the Bikini ash were considered to be urgently needed items of information in estimating the possible hazard due to the internal as well as the external irradiation from the health physics point of view.
Nishiwaki, Yasushi;  Nuclear Reactor Laboratoroy, Kinki University, Fuse City, Osaka Precture (Japan)]
- Nuclear Reactor Laboratory, Tokyo Institute of Technology, Tokyo (Japan)