EXPERIMENTAL STUDY ON NEUTRON CORRELATION ANALYSIS FOR A SUBCRITICAL SYSTEM DRIVEN BY A PULSED SPALLATION NEUTRON SOURCE IN KUCA

Kunihiro Nakajima,Kengo Hashimoto,Tadafumi Sano,Kazuki Takahashi,Masao Yamanaka,Cheol Ho Pyeon,Atsushi Sakon,Sin-Ya Hohara,M Margulis,P Blaise

doi:10.1051/epjconf/202124709019

Kunihiro Nakajima, Kengo Hashimoto + Show 8 more

Open Access

https://doi.org/10.1051/epjconf/202124709019

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Abstract

The Feynman-α and the Rossi-α methods have been frequently employed to determine the subcriticality of subcritical reactor systems driven by Poisson source such as Am-Be neutron source. In actual accelerator-driven systems (ADS), a spallation device will be applied as an intense neutron source. This device will be probably operated in a pulse mode and it is impossible to apply a conventional analysis method to determine the subcriticality in any ADS. In previous theoretical studies, some advanced formulae of neutron correlation analysis for spallation neutron source have been presented. However, the experimental study has been hardly reported to date. The major objectives of this study are to examine experimentally an applicability of these complicated formulae to a subcritical reactor system driven by an actual pulsed spallation neutron source and to determine the prompt-neutron decay constant α of the system. To achieve these goals, we constructed an ADS core at the Kyoto University Critical Assembly (KUCA). The core was composed of highly-enriched uranium fuel assemblies surrounded by many polyethylene reflector assemblies. We carried out a series of the Feynman-α and the Rossi-α analyses for the system driven by pulsed spallation source. As a result, the prompt-neutron decay constants were experimentally obtained by using a fitting formula. The prompt-neutron decay constants determined by Feynman-α and Rossi-α analyses agrees with each other within a statistical error range of least-squares fitting.

Highlights

The Feynman-α and the Rossi-α methods have been frequently employed to determine the subcriticality of subcritical reactor systems driven by Poisson source such as Am-Be neutron source [1,2]
In actual accelerator-driven system (ADS), a spallation device will be applied as an intense neutron source
To achieve the above goal, a subcritical reactor system was constructed in the Kyoto University Critical Assembly (KUCA) [6] and the system was driven by a spallation neutron source to carry out a series of the Feynman-α and the Rossi-α analyses for the pulsed spallation source

Summary

INTRODUCTION

The Feynman-α and the Rossi-α methods have been frequently employed to determine the subcriticality of subcritical reactor systems driven by Poisson source such as Am-Be neutron source [1,2]. The major objectives of this study are to examine experimentally an applicability of these complicated formulae to a subcritical reactor system driven by an actual spallation neutron source and to determine the prompt-neutron decay constant α of the system. To achieve the above goal, a subcritical reactor system was constructed in the Kyoto University Critical Assembly (KUCA) [6] and the system was driven by a spallation neutron source to carry out a series of the Feynman-α and the Rossi-α analyses for the pulsed spallation source.

EXPERIMENT

AND DISCUSSION

CONCLUSION