Survey on effect of crystal texture of beryllium on total cross-section to improve neutronic evaluation in JMTR

Takemoto, Noriyuki ; Imaizumi, Tomomi; Kimura, Nobuaki ; Tsuchiya, Kunihiko ; Hori, Junichi*; Sano, Tadafumi*; Nakajima, Ken*

Neutronic evaluations in JMTR have been performed for irradiation tests by Monte Carlo method with thermal neutron scattering law, S(, ), data for beryllium metal, etc. The calculation accuracy of fast and thermal neutron fluxes are 10% and 30%, respectively. Analytical and experimental investigations to achieve higher calculation accuracy, especially for the thermal neutron flux up to the fast neutron flux level, have been therefore performed to offer higher value data technically to the JMTR users. In order to investigate an effect of fabrication method of beryllium material on the calculation accuracy, total cross-sections of beryllium specimens were measured using KURRI-LINAC, and it was found that the total cross-section was different from the theoretical one, and depended on the crystal texture, etc. The S(, ) was adjusted based on the measured data, and the applicability to the neutronic evaluation in the JMTR was verified.