Heavy reflector experiment in the IPEN/MB-01 reactor

This experiment performed in the IPEN/MB-01 research reactor facility is devoted to the measurements of physical parameters of a light water core surrounded by a stainless steel reflector. Several plates of SS-304 (3 mm thick) were introduced in the west face of the core of the IPEN/MB-01 reactor. The experimental results comprise several measured quantities such as: critical control bank positions, reactivity and relative power density distribution as a function of the number of SS-304 plates. The experimental results show clearly the competition between neutron absorption and neutron reflection in the SS-304 plates. The theoretical analysis was performed in a twofold independent approach. CEA/Cadarache used the Monte Carlo code TRIPOLI4 with JEFF3.1 library to analyse the experimental data while IPEN used the coupled NJOY/AMPX-II/TORT with ENDF/B-VI.8 and MCNP-5 with ENDF/B-VII.0. All calculation methodologies show applicability to describe the physics involved in the heavy reflector system. The quality of the recently released new nuclear data libraries (JEFF3.1 and ENDF/B-VII.0) was addressed and it was shown that these new data have a better quality than older libraries such as ENDF/B-VI.8. (authors)