Application of dynamic mode decomposition to Rossi-α method in a critical state using file-by-file moving block bootstrap method. Issue 9 (2nd September 2022)

• Record Type: Journal Article
• Authors: Endo, Tomohiro; Nishioka, Fuga; Yamamoto, Akio; Watanabe, Kenichi; Pyeon, Cheol Ho
• Is Part Of: Journal of nuclear science and technology. Volume 59:Issue 9(2022)
• Page Start: 1117
• Page End: 1126
• Publication Date: 2022-09-02
• Subjects: Prompt neutron decay constant -- Rossi-α method -- critical experiment -- dynamic mode decomposition -- bootstrap method -- KUCA -- validation -- JENDL -- FRENDY -- MCNP; Nuclear engineering -- Periodicals; Nuclear physics -- Periodicals; Nuclear energy -- Periodicals; 621.4805
• DOI: 10.1080/00223131.2022.2030260
• Languages: English
• ISSNs: 0022-3131

Abstract

ABSTRACT: Prompt neutron decay constant α in a critical state is useful information to validate the numerically predicted ratio of the point kinetics parameters β e f f / ℓ, where β e f f and ℓ are the effective delayed neutron fraction and prompt neutron lifetime, respectively. To directly measure α in a target critical system, this study proposes the application of the dynamic mode decomposition (DMD) to the reactor noise analysis based on the Rossi- α method. The DMD-based Rossi- α method enables us to robustly estimate the fundamental mode component of α from the Rossi- α histograms measured using multiple neutron detectors. Furthermore, the file-by-file moving block bootstrap method is newly proposed for the statistical uncertainty quantification of α to prevent huge memory usage when the neutron count rate is high and/or the total measurement time is long. A critical experiment has been conducted at Kyoto University Critical Assembly to demonstrate the proposed method. As a result, the proposed method can uniquely determine the α value of which the statistical uncertainty is smallest. By utilizing this experimental result of α, numerical results of β e f f / ℓ ratio using the continuous energy Monte Carlo code MCNP6.2 with recent nuclear data libraries, which are processed by the nuclear data processing code FRENDY, are validated. Graphical Abstract: uf0001