Joneja, O. P.Plaschy, M.Jatuff, F.Luthi, A.Murphy, M.Seiler, R.Chawla, R.2010-09-172010-09-172010-09-17200110.1016/S0306-4549(00)00079-7https://infoscience.epfl.ch/handle/20.500.14299/53843A detailed three-dimensional, continuous-energy MCNP4B model of the LWR-PROTEUS critical facility has been developed for the analysis of whole-reactor characteristics using ENDF/B-V, ENDF/B-VI and JEF-2.2 cross-section sets. The model has been applied to the determination of the critical loading, as well as the evaluation of reactivity worths for safety/shutdown rods, control rods, and individual driver-region fuel rods. The initially obtained results for the first configuration investigated (Core 1B) indicated that, for the same geometrical and materials specifications, the ENDF/B-V data library yields the closest critical prediction (discrepancy of 64040 pcm), followed by ENDF/B-VI (98040 pcm) and JEF-2.2 (134040 pcm). The differences in results between the three data libraries were studied by considering the contributions of individual materials to the neutron balance. 235U and 238Pu cross-sections from JEF-2.2, for example, explain an effect of ~400 pcm. Refinement of the materials specifications in the MCNP4B whole-reactor model, in particular the impurities assumed for the graphite driver of the driver and reflector regions, has been shown to reduce the final discrepancy of the ENDF/B-V based keff result to ~0.2%. The MCNP4B results for relative reactivity effects, such as control rod worths, are found to agree within experimental errors with the measured valuesfission reactor core controlfission reactor physicsfission reactor safetyMonte Carlo methodsreactivity (fission reactors)text::journal::journal article::research article