Research on high precision reactor noise analysis based on neutron transport theory for reactor core diagnosis

2021 Fiscal Year Final Research Report

• Project/Area Number: 17K07011
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Nuclear engineering
• Research Institution: Kyoto University
• Principal Investigator: Yamamoto Toshihiro 京都大学, 複合原子力科学研究所, 准教授 (70355048)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: 中性子 / 炉雑音 / 原子炉 / 異常診断 / 輸送理論 / モンテカルロ / 周波数領域

Outline of Final Research Achievements

A Monte Carlo calculation method for analyzing neutron noise propagation in a nuclear power reactor core caused by abnormal vibration of an in-core component has been developed. The method has been applied to analyses of neutron noise experiments in critical assemblies, where the neutron noises were produced by vibration of fuel or neutron absorber. Whereas the method does not yield sufficiently accurate result for the fuel vibration, reasonably accurate result is obtained for the absorber vibration. The method is applied to an experiment where void velocity in a water channel was measured using noise method in the critical assembly. A unique feature in the velocity measurement is revealed via the Monte Carlo analyses. The deviation of neutron noise in a reactor core from the point kinetics theory is investigated. A sensitivity analysis method for calculating sensitivity of neutron noise with respect to group constants that are used for neutron noise analyses has been developed.

Free Research Field

原子力学

Academic Significance and Societal Importance of the Research Achievements

モンテカルロ法の粒子輸送計算では、定常状態或いは時間依存の解析が従来から行われてきたが、原子力分野において複素数のウェイトを用いた周波数領域の解析は、研究代表者が世界に先駆けて開発したものである。この手法の炉心異常診断等への適用可能性を示したことで、モンテカルロ法の適用分野を大きく切り拓いたといえる。成果はCORTEX計画において高精度参照解として採用され計画の推進に貢献した。