COMPARISON OF MONTE-CARLO AND CELL CODE RESULTS FOR MOX FUEL IN PWR LATTICES WITH VARYING MODERATION ON THE BASIS OF MEASUREMENT DATA

Increased MOX contents in PWR cores lead to harder neutron flux spectr a. As a consequence the resonance energy region gains increasingly in importance in spectral calculations. Experiments for an improved MOX-f uel utilization in PWRs were conducted at the Swiss PROTEUS critical f acility in an international cooperation from 1981 to 1993, offering a comprehensive data base for comparisons with nuclear data libraries an d codes. To access and improve the accuracy of MOX-fueled core calcula tions new consistent nuclear cross-section libraries based on JEF-2.2 were created at the Institute for Spaceflight and Nuclear Reactor Tech nology (IfRR) at the Technical University Braunschweig for two differe nt cell codes SPEKTRA and CASMO and the Monte Carlo code MCNP. With th e help of these codes reaction rates of four PROTEUS test-lattices wit h varying degrees of moderation were analysed in detail at Siemens/KWU and IfRR and compared with measured values.