From integral experiments to nuclear data improvement

Abstract
Target accuracy on LWR neutronics parameters is 2 to 5 times lower than the a priori uncertainty (1σ) due to nuclear data. This paper summarizes the experimental facilities and the integral measurements that are required for code qualification. The rigorous use of integral information through trend analysis method is described. Trends on JEF2 data from Keff measurements and P.I.Es are presented. These trends were accounted for in the new JEFF3 evaluations. The role of fundamental experiments, such as worth measurement of separated isotopes, is emphasized. Some recent improvements in JEFF3.1 (²³⁷Np, ²³⁹Pu) are extracted from these specific experiments.