Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kudo, Akira*; Fujikawa, Yoko*
JNC TJ8400 2000-010, 67 Pages, 2000/02
JNC-TJ8400-2000-010.pdf:2.17MB
The first and second environmental releases of man-made 
Pu came from nuclear explosions at Alamagordo and Nagasaki in 1945. The release at Nagasaki was more serious than at Alamagordo, because it happened in an area with a high population density. Unfissioned Pu and various fission products have been interacting here with various environmental materials (soils, sediments, and plants) under wet and temperature conditions for more than 45 years. To assess the environmental mobility of Pu, the distributions of radionuclides from this release were investigated at Nishiyama where heavy black rain containing unfissioned plutonium and fission products fell 30 minutes after the nuclear explosion. The vertical distributions of 
Cs and Pu were determined in unsaturated soil cores up to 450cm deep. Most radionuclides were found in the soil column 30cm from the ground surface. However, Pu were detected in the groundwater as well below a depth of 200cm. No Cs was found below 40cm from the ground surface or in groundwater. These observations reveal that about 3% of the total Pu have been migrating in the soil at a faster rate than the remaining Pu. Sharp peak of Cs and Pu, indicating heavy deposition from the Nagasaki local fallout of 1945, were found in sediment cores collected from the Nishiyama reservoir. Pu peaks were unexpectedly discovered in pre-1945 sediment core sections. NO Cs was found. By contrast to the distribution in sediment cores, Cs in tree rings had spread by diffusion from the bark to the center of the tree without holding a fallout deposition record. Most of the Pu was distributed in the tree rings following a similar deposition record to that found in sediment cores. Furthermore, a very small amount of Pu (about 1%) was found unexpectedly in pre-1945 tree rings. The only reasonable ...
Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Wakaida, Ikuo; Iwata, Yoshihiro*; Jung, K.*; Hasegawa, Shuichi*
no journal, ,
For the radioactivity evaluation regarding to the accident of TEPCO Fukushima Daiichi Nuclear Power Station, time-consuming and skills-required sample pretreatments for 
Sr analysis (radiometric or ICP-MS analyses) is serious issue. We are developing a ultra-sensitive and rapid analytical technique for Sr by combining resonance ionization spectroscopy, in which only the atoms of specific isotope can be ionized using the slight difference in level energy, and ion trap technique, in which only the ions of specific isotope can be trapped for a long duration to observe them with high sensitivity. In this study, we applied a continuous-wave isolated-core excitation technique (cw-ICE) for the first time to search for highly efficient and isotope-selective ionization schemes, especially for the Rydberg series converging to the 5
ionic levels, of which information is quite scarce. As a result, we have revealed a detailed level-structure of autoionizing 5(nl) series of Sr atoms.
Sr/Y in high gamma radiation backgrounds utilizing Cherenkov radiation directivityTerasaka, Yuta; Sato, Yuki; Furuta, Yoshihiro*; Kubo, Shin*
no journal, ,
no abstracts in English