Integral experiment of ¹²⁹I(n, γ) reaction using fast neutron source in the ‘YAYOI’ reactor

ABSTRACT

The present study analyzes an integral experiment performed in the fast-neutron reactor ‘YAYOI’ of the University of Tokyo to validate the ¹²⁹I (n,γ) cross-section. An iodine-129 sample and 15 neutron flux monitors were irradiated with fast neutrons in the Glory hole of the reactor. Capture reaction rates of ¹²⁹I were obtained by measurement of gamma rays emitted through the decay of ¹³⁰I, and the 15 neutron flux monitors helped validate the computed fast-neutron flux spectrum in the Glory hole. By comparing the experimental and calculated reaction rates for ¹²⁹I, the present study reveals that the ¹²⁹I (n,γ) cross-section of JENDL-4.0 should be reduced by 18% in the 10 keV–3 MeV energy range and supports the data by Noguere et al. below 100 keV.

Graphical abstract

KEYWORDS:

• Iodine-129
• iodine-130
• activation
• integral experiment
• JENDL-4.0
• fast neutron source reactor
• YAYOI

Acknowledgments

The authors would like to greatly appreciate Professor Emeritus Yoshiaki OKA, Drs. Yuki ISHIWATARI (present affiliation: GE Hitachi), Isao SAITOH, Atsushi YASUMI, Tsutomu NAKAGAWA, and Yukio MABUCHI of the University of Tokyo for their cooperation. One of the authors (S. Nakamura) also wishes to appreciate Dr. Nobuyuki IWAMOTO and Dr. Osamu IWAMOTO of JAEA for their constructive and valuable comments.

This work has been carried out in part under a collaborative research project at Nuclear Professional School, School of Engineering, The University of Tokyo.

Disclosure statement

No potential conflict of interest was reported by the author(s).