Reactor

Abstract. A nuclear data library production system has been written to recover and format nuclear data required in the recently released advanced lattice code DRAGON Version4. State-of-theart resonance self-shielding calculations require information that goes beyond WIMS-D type models. Dilution-dependent cross sections are required for all resonant reactions and for more than 10 specific dilutions. Ultra-fine multigroup cross section data is also required in the resolved energy domain. Another important aspect of advanced lattice codes is the explicit treatment of most neutron induced reactions in the burnup calculation. We need to perform power normalization due to energy from various neutron induced and decay reactions. Eventhough the decay energy contributes very little relative to the neutron induced reactions, the information will be very useful for post irradiation behavior of fuel. All this information is collected using DRAGR, a new post-processing module in NJOY99, and formatted in a single direct access hierarchical database. Burnup data is also recovered and the short-life isotopic data is automatically lumped. Moreover, PyNjoy, an object-oriented script, was developed to automate the revovery of ENDF/B evaluations, the building, and the management of the database. This system was developed under the Lesser General Public License and is openly available. 1 Advanced capabilities in Dragon Version4 This presentation is related to the production of the isotopic cross section library, an important component of the reactor physics computational system depicted in figure 1. The pro-posed nuclear data library production system is intended for use in association with advanced lattice codes. ENDF/B data Isotopic cross-section librar