SUBTHERMAL FISSION CROSS-SECTION MEASUREMENTS FOR 233U, 235U AND 239Pu


C. Wagemans*, P. Schillebeeckx, A.J. Deruytter and R. Barthélémy

Commission of the European Communities, Joint Research Centre - Geel-Establishment
Central Bureau for Nuclear Measurements, 2440 Geel, Belgium

The 233U, 235U and 239Pu(n,f) cross sections have been measured at GELINA down to 2 meV neutron energy using a liquid nitrogen cooled methane moderator. The neutron flux has been determined via the 6Li(n,α)t reaction. These measurements considerably enlarge the database in the subthermal region, resulting in more reliable values for the Westcott gf-factor and its temperature dependency.

These new σf(E)-data have also been used to calculate selected fission integrals.

KEYWORDS: 233U, 235U, 239Pu, fission cross-section, range 0.002-20 eV