Data Assimilation Using Subcritical Measurement of Prompt Neutron Decay Constant

• Endo, Tomohiro

• Yamamoto, Akio

Abstract

The prompt neutron decay constant α in a steady-state subcritical system can be directly measured using a reactor noise analysis method such as the Feynman-α method. To reduce the nuclear data–induced uncertainty of keff for a target system, this study investigates the applicability of data assimilation techniques, i.e., the bias factor method and the cross-section adjustment method, based on a subcritical measurement of α conducted at Kyoto University Critical Assembly (KUCA). The sensitivity coefficients of keff and α with respect to the nuclear data were efficiently estimated using a deterministic SN transport code with first-order perturbation theory. As a result, the a priori relative uncertainty of keff due to the 56-group SCALE covariance data can be reduced if there is strong correlation between the measured α and the target keff. The experimental value of α contributes to improving the nuclear data of total fission spectrum χ and total fission neutron number ν via strong correlations between χ and prompt χp and between ν and prompt νp, by utilizing the sensitivity coefficients of α with respect to prompt χp and νp.

Published online: 09 Mar 2020 ファイル公開：2021/03/09 ファイル差し替え：2021/06/25

Journal

• Nuclear Science and Engineering

  Nuclear Science and Engineering 194 (11), 1089-1104, 2020

  Taylor & Francis

Keywords

• Prompt neutron decay constant
• Feynman-α method
• perturbation theory
• bias factor method
• cross-section adjustment method

Details

• CRID: 1051975278335663104
• NII Article ID: 120006894688
• DOI: 10.1080/00295639.2020.1720499
• ISSN: 1943748X
• ISSN: 00295639
• HANDLE: 2237/00032880
• Web Site: https://nagoya.repo.nii.ac.jp/records/30693
• Web Site: https://www.tandfonline.com/doi/pdf/10.1080/00295639.2020.1720499
• Text Lang: en
• Article Type: journal article
• Data Source:
  • IRDB
  • Crossref
  • CiNii Articles
  • KAKEN