Analysis of benchmark experiments of effective delayed neutron fraction βeff at FCA

Abstract

To finalize the benchmark experiments of the effective delayed neutron fraction β eff at the FCA facility of the Japan Atomic Energy Research Institute, the β eff's were compared between different measurement methods. The final values of the β eff were 42pcm±3%, 364pcm±3% and 251pcm±2% in the cores of XIX-1, XIX-2 and XIX-3 respectively. Correlations of the β eff between the different methods were considered to derive these final values. In the analysis of experiments, two sets of delayed neutron data were tested: JENDL-3.2 and ENDF/B-VI. Calculation-to-experiment ratios(C/E's) of the β eff were 1.004, 1.005 and 0.972 in the cores of XIX-1, XIX-2 and XIX-3 respectively when the delayed neutron data of JENDL-3.2 were used. The C/E's of the β eff were 1.033, 0.985 and 0.992 in the cores of XIX-1, XIX-2 and XIX-3 respectively when the delayed neutron data of ENDF/B-VI were used. Recommendations for the D.N. yields were drawn from these C/E's to improve the prediction accuracy of β eff of fast reactor.