Crystallite domain size measurement of beryllium block used in experiments at FNS and re-analysis of FNS beryllium integral experiment

Konno, Chikara  

A beryllium integral experiment with DT neutrons at JAEA/FNS was performed 35 years ago. Various analyses of the experiment have shown that calculated reaction rates of the Li(n,)T, Au(n,)Au and U(n,fission) reactions, which are sensitive to low energy neutrons, overestimate the measured ones. Recently, European Spallation Neutron Source (ESS) group presented that the thermal scattering law data of beryllium change depending on crystallite domain size of beryllium metal due to the extinction effect. If the data are applied to the analysis of the FNS beryllium integral experiment, the overestimation problem may be solved. However, crystallite domain size of beryllium block used in the experiment has not been measured. Here, it was measured as 27.31.7 m with the method based on ASTM E112-13. Then the FNS beryllium integral experiment was re-analyzed based on the data.