Identification of plutonium released from Nagasaki atomic bomb; Approach of measurement of Pu/Pu isotope ratio by ICP-MS

Kokubu, Yoko   

This presentation is one of the invited talks at a special session of "Advances and future prospect of A-bomb researches" in the 2008 Annual Meeting of the Japan Society of Nuclear and Radiochemical Sciences. Alpha-ray spectrometry of Pu was mainly used to assess plutonium from Nagasaki atomic bomb in the previous studies. However it was difficult to discriminate the plutonium due to atomic explosion in Nagasaki from global fallout by analysis of the -ray spectrum. In this study, Pu/Pu ratio measured by ICP-MS was used to identify the source of Pu and distributions of the Pu in sediment and soils were reported. Depth profile of the Pu in a sediment core collected at Nishiyama reservoir, Nagasaki city was determined to obtain depositional record of the Pu from the atomic bomb for 60 years. The Pu was measured in surface soils collected around the hypocenter of the atomic bomb to identify geological distribution of the Pu from the atomic bomb.