Neutron cross section evaluations for actinides at intermediate energies: sup 2 sup 3 sup 9 Pu

Investigations aimed at the development of neutron cross section evaluations for actinides performed at IPPE in collaboration with Royal Institute of Technology, Stockholm at intermediate energies in the range of 0-200 MeV are briefly described on the example of sup 2 sup 3 sup 9 Pu. The coupled-channels optical model is used to calculate the neutron total, elastic and reaction cross sections and the elastic scattering angular distributions. Evaluations of the neutron and charged particle emission cross sections and of the fission cross sections are obtained on the basis of the statistical description that includes direct, preequilibrium and equilibrium mechanisms of nuclear reactions. The Kalbach parametrization of angular distributions is used to describe the double-differential cross sections of emitted neutrons and charged particles in ENDF/B-VI format. These investigations resulted in creation of complete neutron and proton data files for sup 2 sup 3 sup 8 U and sup 2 sup 3 sup 2 Th and neutron data file for sup 2 sup 3 sup 9 Pu up to 150 MeV. These files were processed with NJOY.