A Survey of Low and Mdium Energy State-of-the-Art Evaluation Techniques

State-of-the-Art evaluations at low and medium Incident neutron energies rely on both theory and experimental data. I will present a survey of the main theories employed to model point-wise and average corss sections from individual or average resonance parameters through practical xamples. Solutions to major difficulties will be given. Special attention will be devoted to calculation of fluctuating fission cross sections due to intermediate structure in the exit channel, from Monte Carlo class-I/-II parameters. Application to plutonium isotopes will be presented. Short and long run evaluation processes involving experiments, raw data reduction, modelization, processing codes and integral data will be eviewed. A discussion of the future of nuclear evaluation code development will connclude the presentation.