The fission cross sections of 230Th, 232Th, 233U, 234U, 236U, 238U, 237Np, 239Pu and 242Pu relative to 235U at 14.74 MeV neutron energy

Abstract

The measurement of the fission cross section ratios of nine isotopes relative to 235U at an average neutron energy of 14.74 MeV is described with particular attention to the determination of corrections and to sources of error. The results are compared to ENDF/B-V and to other measurements of the past decade. The ratio of the neutron induced fission cross section for these isotopes to the fission cross section for 235U are: 230Th—0.290 ± 1.9%; 232Th—0.191 ± 1.9%; 233U—1.132 ± 0.7%; 234U—0.998 ± 1.0%; 236U—0.791 ± 1.1%; 238U—0.587 ± 1.1%; 237Np—1.060 ± 1.4%; 239Pu—1.152 ± 1.1%; 242Pu—0.967 ± 1.0%. The remaining 36 possible fission cross section ratios and their errors are determined from these results and the covariance information.