Determination of Lambda-Mode Eigenvalue Separation of a Thermal Accelerator-Driven System from Pulsed Neutron Experiment

Abstract

Critical Assembly (KUCA), various experiments on thermal ADS with a pulsed spallation source are planned.In such an ADS, neutron flux distribution may be sensitive to the injection of neutrons, and the high sensitivity results in various spatial effects.In this study, a pulsed neutron experiment with 14 MeV neutrons was carried out in a thermal ADS of KUCA, to determine the !-mode eigenvalue separation, which is a quantitative indication of spatial effects.An original data-processing technique was applied to infer prompt-neutron decay constants of fundamental and higher modes from neutron count decay data, and then the eigenvalue separation around 13%k=k was obtained from these decay constants.