Abstract
The neutron emission rates from five very pure actinide samples (Th-232, Np-237, Pu-239, Pu-241 and depleted uranium) were measured following equilibrium irradiation in fast and thermal neutron fluxes. The relative abundances (alphas) for the first four groups were calculated from the delayed neutron emission (counts vs. time) data using Keepin's 6-group decay constants (lambdas) for Th-232, Pu-239 and depleted uranium (both fast and thermal neutron induced fissions). The relative abundances (alphas) for the first five groups were calculated for the fast neutron induced fission of Np-237 using the 7-group lambdas obtained by Charlton (1997). The relative abundances for the first five groups were also calculated using the 7-group lambdas proposed by Loaiza and Haskin (2000), the 8-group lambdas proposed by Campbell and Spriggs (1998) and the 8-group lambdas proposed by Piksaikin (2000) for all of the samples (fast neutron induced fission only for Th-232 and Np-237, fast and thermal neutron induced fission for the remainder). Fission product yield and delayed neutron emission probability data from the ENDF-349 and JEF 2.2 nuclear data libraries were also used to simulate neutron emission data from the samples. The calculated neutron yield curves were used to obtain group relative abundances for each of the five actinide samples (fast neutron induced fission only for Th-232 and Np-237, fast and thermal neutron induced fission for the remainder) based on each set of proposed lambdas. The relative abundances obtained from the experiments and calculations are compared and the differences are noted and discussed.
Stone, Joseph C. (2001). Delayed neutron measurements for Th-232, Np-237, Pu-239, Pu-241 and depleted uranium. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2001 -THESIS -S7454.