Evaluation of the neutron cross sections of 235u in the thermal energy region. Final report

The objective of this work on project 512 has been to improve the knowledge of the thermal cross sections of the fissile nuclei as a step toward providing a standard data base for the nuclear industry. In the course of this work the methodology has been developed to perform objective studies to determine best-estimate shapes of the partial cross sections in the thermal neutron energy region. Results include (1) the assessment of the shape uncertainties of the partial cross sections (2) the development of a recommended set of 2200 m/s (0.0253 eV) values of the parameters and the probable range of further adjustment which might be made (3) the result of a common interpretation of energy-dependent absolute cross-section data of different measurements to yield a consistent set of experimental 0.0253-eV values with rigorous error estimates; and (4) normalization factors for relative fission and capture cross sections on a common basis with rigorous error estimates