Prompt Neutron Decay Constant Measurements on a Copper Reflected Intermediate Enrichment Uranium System with Lead Intersitial

摘要

Table 1 includes all of the measured values of the prompt neutron decay constant for the IEU/Pb Zeus configuration. Table 1 also includes the inferred prompt neutron decay constant at delayed critical. The prompt neutron decay constant at delayed critical for this system is -56350.4 ± 552.4 s~(-1). This result compares well to other Zeus systems as indicated by the results in Table 2. The IEU/Pb experiment is expected to have a rather hard spectrum and it has one of the hardest neutron spectrums from any Zeus experiment. In fact, only the all uranium configurations had a harder neutron spectrum. The all HEU Zeus is expected to have a harder neutron spectrum and a larger magnitude prompt neutron decay constant at delayed critical which had a value of-89909 ± 816.9 s~(-1). The HEU/Pb Zeus is expected to have a softer neutron spectrum because the fuel to lead ratio is smaller and the fuel has a lower fission threshold (less U-238). As such, the HEU/Pb Zeus should have a smaller magnitude prompt neutron decay constant at delayed critical which had a value of-38255.2 ± 324.8 s~(-1).