JENDL-3 Fission Product Nuclear Data Library

Abstract

Neutron nuclear data in the energy range between 10⁻⁵ eV and 20MeV have been evaluated for 172 nuclides from ₇₅As to ₁₆₉Tb in the fission product mass region to provide data for the JENDL-3 fission product nuclear data library. Evaluation was made on the basis of recent experimental data reported up to 1988 and the nuclear model calculations. Resonance parameters have been evaluated on the basis of measured data set and a REPSTOR system developed in JAERI. The spherical optical model and statistical theory were applied to calculation of the total, capture, elastic and inelastic scattering cross sections, and the multistep evaporation model and pre-equilibrium theory were used for threshold reaction cross section calculations. For the even-even nuclides around fission yield peaks, direct inelastic scattering cross sections were calculated with the distorted wave Born approximation. Nuclear model parameters, such as optical model parameters, level density parameters, x-ray strength functions and Kalbach constant of the pre-equilibrium model were determined so as to give a good agreement between the calculated and measured cross sections. The parameter systematics were obtained as a function of nuclear mass or atomic number. For thermal capture cross sections, a simple relation between measured and calculated cross sections was found as a function of level spacing. The evaluated results were compiled in the ENDF-5 format.

KEYWORDS:

• neutrons
• cross sections
• JENDL-3
• fission products
• evaluation
• nuclear model parameter
• optical model parameter
• level density parameter
• gamma-ray strength function
• resonance parameter