MEASUREMENT OF PROMPT NEUTRON DECAY CONSTANT OF CFBR-II AT NEAR DELAYED CRITICALITY USING RANDOMLY PULSED NEUTRON METHOD

摘要

Prompt neutron decay constant of CFBR-II(China's Fast Burst Reactor) was measured by the randomly pulsed neutron method when the reactor was at the reactivity of-0.1$. A liquid scintillation detector was used to detect the leakage neutrons and the timing uncertainty of the detection system was less than 3ns. The detector and the Cf-252 fast ionization chamber were placed at several positions. Totally 5 prompt neutron timing distribution curves were obtained and the prompt neutron decay constant was 0.610us~(-1) in average with the uncertainty of 0.030us~(-1), which was in good agreement with the M.C. calculation.