Cross Sections for ²³⁹Pu(n,f) and ²⁴¹Pu(n,f) in the Range En = 0.01 eV to 200 MeV

The ²³⁹Pu and ²⁴¹Pu neutron-induced fission cross sections have been measured from subthermal energies to 200 MeV. These measurements are part of a campaign to measure fission cross sections with high precision in support of advanced fast reactor technology. Plutonium-241 is the most active target measured in this program to date, with a half-life of 14.4 yr. The results for ²³⁹Pu are in good agreement with previous experiments and add new information to the limited knowledge on the fission cross section above 30 MeV. Discrepancies of up to 30% between the evaluations and the experimental data for ²⁴¹Pu are found in the fast region, which is of particular importance for fast spectrum reactor technology, and a reevaluation of the fission cross section for this isotope is recommended.