| Project/Area Number |
15560726
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Kyoto University, Research Reactor Institute |
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Principal Investigator |
MISAWA Tsuyoshi Kyoto University, Research Reactor Institute, Associate Professor, 原子炉実験所, 助教授 (70219616)
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| Co-Investigator(Kenkyū-buntansha) |
UNESAKI Hironobu Kyoto University, Research Reactor Institute, Associate Professor, 原子炉実験所, 助教授 (40213467)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Subcriticality / Higher mode flux / Source multiplication method / Feynman-α / Critical Assembly / Eigenvalue / 臨界集合体 / 加速器駆動未臨界炉 / KUCA |
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| Research Abstract |
It is a problem to avoid nuclear criticality accident during handling of nuclear materials. It is important to install the device which measured a subcriticality in real time as a method to prevent a critical accident. However, precision is not good with a subcritical degree of an arbitrary system, and a method to measure is not yet developed by a reason that space dependence of a measurement result becomes big in subcritical state. A purpose of this study is new in subcriticality measurement technique which based on consideration of highly mode function.
Among these subcriticality measurement methods, neutron source multiplication method(NSMM) is one of the well-known methods for this purpose, and the advantage of this method is the simplicity of measurement using an external neutron source and neutron detectors, moreover, the data processing is also very easy. To take into account of spatial dependence of neutron flux distribution in subcritical state, new NSMM with considering higher mode fluxes for subcriticality measurement is developed, where the neutron flux distribution in subcritical state is expanded in a series of higher mode fluxes of critical state. To confirm the applicability of this method, subcriticality measurement experiments were carried out at Kyoto University Critical Assembly(KUCA). For comparison, subcriticality was also measured by other methods ; the original NSMM and Feynman-α method that is one of neutron noise analysis. From these results, it was found that the results of the present method including higher mode fluxes showed that the discrepancy between different detectors became much smaller even in large subcritical state compared with other experimental methods.
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