Measurement and Analysis of Leakage Neutron Spectrum from a Spherical Pile of Silicon with Incident 14 MeV Neutrons

摘要

Absolute leakage neutron spectrum in the energy range between 0.1 and 15 MeV from a silicon spherical pile of 60-cm diameter was measured using an intense 14 MeV pulsed neutron source, OKTAVIAN, for the purpose of the benchmark validation of the nuclear data of silicon in JENDL-3.2, JENDL-3.3, ENDF/B-VI (release 2), ENDF/B-VI (release 5) and EFF-2.4. The neutron spectrum was compared with the calculated results using MCNP with different nuclear data. For estimating sensitivity of the individual cross section, the calculations were also performed using modified JENDL-3.2 based data libraries. It was found that the all nuclear data could predict the measured spectrum with the measurement fairly well. ENDF/B-VI (release 2) gave considerably large discrepancy over the whole energy region presumably caused by the inadequate inelastic scattering cross section values. The discrepancy found in the JENDL-3.2, JENDL-3.3 and EFF-2.4 between 5 and 10MeV could be attributed to the too low values of the discrete inelastic scattering cross section values. The prediction with ENDF/B-VI (release 5) was almost satisfactory over whole energy region.