Speaker
Description
The CONRAD computer code is being developed by the nuclear data group of CEA Cadarache by since mid-2000. It was originally designed to analyse neutron-induced reactions in the resonance energy range and then, was extended to higher energies (several MeV) treatment with inclusion of charged-particles penetration factor. In the resonance range, nuclear models implemented in the CONRAD program rely on R-matrix model fits with in particular, improved treatment of the fission penetration factor. A procedure was also implemented to manage the so-called ‘Thermal Neutron Constants’, especially devoted to the 239Pu, 241Pu, 233U and 235U nuclei. A two-step (n,gf) process was made available to describe the fluctuations of the prompt neutron multiplicity in the resonance range. The neutron continuum energy region of the observed cross sections can be analysed either with the TALYS code or an in-house optical model code named CCCP that is followed by Hauser-Feshbach calculations according to the compound nucleus deexcitation channels. Non-model least squares fitting procedures have been tested for neutron cross sections adjustment in the “continuum” energy range, and such, extensively applied in the framework of the standard cross section group at the IAEA (Vienna).
This presentation will focus on the various evaluation works performed with CONRAD on minor and major actinides (235,238U, 237Np, 239,240,242Pu) in the resonance range but also in the neutron continuum region with special emphasis on the experimental corrections suitable to reproduce time-of-flight experiments. Issues on the Doppler broadening corrections with a crystal lattice model will be discussed.
Reference
[1] C. De Saint Jean et al., CONRAD – a code for nuclear data modeling and evaluation, EPJ Nuclear Sci. Technol. 7, 10 (2021)