Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Sato, Akinori; Kosaka, Ichiro; Kaji, Naoya
no journal, ,
The Japan Atomic Energy Agency (JAEA) is now constructing Radioactive Material Analysis and Research Facility (The administration building, Laboratory-1 and Laboratory-2). Laboratory-2 is planned as a hot laboratory handling the fuel debris and conducting radioactive analysis and mechanical/chemical characterization of fuel debris. Therefore, some specific issues, such as shielding and criticality safety should be investigated as preliminary studies. For evaluations of radiation shielding, the conservative conditions were adopted such as conservative source intensity, the effect of activated structural material and excluding self-shielding system. As a preliminary evaluation of criticality safety, the critical mass limit was evaluated under conservative conditions such as fresh fuel and 30 cm water reflection. Through evaluations, it is found that shielding design of Laboratory-2 is achievable even if calculations are performed under conservative conditions. Through preliminary calculation of critical mass limit, handling of the assumed amount of fuel debris (5 kg) is concluded to be feasible.
Suzuki, Miho; Kimura, Yasuhiko; Takano, Masahide; Mita, Naoaki
no journal, ,
Iwasaki, Maho; Sato, Soichi
no journal, ,
The Tohoku Earthquake and the tsunami that followed occurred in March 2011. The surge from the tsunami caused loss of cooling system in Tokyo Electric Power Company Holdings Fukushima Daiichi Nuclear Power Station (1F). The loss of cooling system allowed the fuel in reactor units 1-3 at least partially meltdown and caused hydrogen explosions in unites 1 and 3. As the results of the explosions, a large amount of radioactive materials were released into the environment and contaminated a vast area containing the 1F site. Japan Atomic Energy Agency, JAEA, currently sets up an Okuma Analysis and Research Center next to the 1F site, which aims at characterizing radioactive wastes and fuel debris generated in the 1F site. Radioactive waste samples taken in the 1F site are planned to be analysed by mainly conventional radiometric methods. These measurements require complicated and time-consuming process including chemical separation and purification in advance. To avoid the chemical separation, Inductively Coupled Plasma-Quadrupole Mass Spectrometry, ICP-QMS, which has an advantage of sensitivity over radiometric analysis for long-lived radionuclides, was applied. Isobaric interference is the major task to be solved for the mass spectrometric analysis. The procedure of the mass-based analytical method for radionuclides and the detailed results for an example case for Zr-93 are described in this presentation.
Watanabe, So; Ogi, Hiromichi*; Arai, Yoichi; Aihara, Haruka; Shibata, Atsuhiro; Nomura, Kazunori
no journal, ,