Production of application libraries for WIMS

The WIMS codes have been developed over a period of 30 years to include sophisticated modelling of many thermal reactor lattices. WIMS6 is currently being developed to include the flexibility of WIMSE together with the case of use seen in LWRWIMS. A new cross-section library is to be released with WIMS6. For the first time since the original WIMSD was written, the library is being generated from completely new differential data based mainly on JEF2.2. Quality Assurance into the XMAS library is achieved in three levels; through general procedures during assembly, by validation studies and by verification. The main general procedure involves forming overall physics quantities (Thermal average cross section, resonance integrals and fission spectrum average values) from the point evaluations and comparing them with similar quantities from the XMAS library. Examples of validation are studies optimizing the background cross-sections at which resonance integrals are tabulated and comparing reaction rates from homogeneous calculations with those formed in Monte Carlo and deterministic codes which represent energy variation of cross-section on a hyperfine energy mesh. Verification involves performing benchmark calculations and comparing results with experiment and calculations with the Apollo code. The current XMAS library contains 140 nuclides based on JEF2.2 evaluations. (author)