2002 Fiscal Year Final Research Report Summary
Study on Fast-Neutron Capture Cross Sections of Long-Lived Nuclear Wastes
| Project/Area Number |
12480137
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear engineering
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
IGASHIRA Masayuki Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Associate Professor, 原子炉工学研究所, 助教授 (10114852)
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| Co-Investigator(Kenkyū-buntansha) |
OHSAKI Toshiro Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Research Associate, 原子炉工学研究所, 助手 (80262327)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Long-Lived Nuclear Wastes / Fast・Neutron Reaction / Capture Cross Sections / Capture Gamma・Ray Spectra / Technetium・99 / Iodine-129 |
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| Research Abstract |
The objectives of this project are to accurately and simultaneously measure the neutron capture cross sections and capture gamma-ray spectra of the very important long-lived nuclear wastes of Tc-99 and I-129 in the incident neutron energy region from 10 to 600 keV and to investigate the fast-neutron capture reaction mechanism by theoretically analyzing these measured data and those of 19 stable fission products and the long-lived minor actinide of Np-237 which were also obtained by our group. The following results were obtained in the term of this project.
(1)Measurements for Tc-99 and I-129
Prompt gamma rays from the neutron capture reaction of Tc-99 or I-129 were measured with a high-sensitive gamma-ray detector, adopting a neutron time-of-flight method with pulsed keV neutrons form the ^7Li(p,n)^7Be reaction by a 1.5-ns pulsed proton beam from the Pelletron accelerator of the Research Laboratory for Nuclear Reactors at the Tokyo Institute of Technology. As a result, the capture cross sections of Tc-99 and I-129 were obtained with the errors of about 5% and about 10%, respectively, in the incident neutron energy region from 10 to 600 keV. As for capture gamma-ray spectra, those of Tcb-99 and I-129 were obtained for the first time in the world.
(2)Theoretical analysis of experimental results
The measured capture cross sections and capture gamma-ray spectra of Tc-99 and I-129 together with those of the other nuclides were simultaneously analyzed, using a computer program based on the statistical model in the nuclear reaction theory. As a result, it was found that the statistical model calculation could reproduce both capture cross sections and capture gamma-ray spectra of Tc-99 and l-129 except for the high-energy part and the corresponding low-energy part in the gamma-ray spectra. Therefore, it was found that the main mechanism of the fast-neutron capture reaction of Tc-99 and I-129 could be explained with the statistical model.
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