Reactor physics related data are available in international data banks, e. g. the International Reactor Physics Benchmark Experiments (IRPhE) databank of the NEA and various activities are co-ordinated through the Nuclear Science Committee (NSC) (NEA Annual Report, 2002). The data are used as a reference for transient analysis to address specific safety issues. For example, a safety issue for PWRs concerns thermal mixing and the impact on neutronics. In 2002, a main steam-line break (SLB) benchmark study was carried out using data from the TMI-Unit 1 PWR. Coupled 3D neutronics/thermal- hydraulics calculational methods were used. For BWRs, reactor stability is an issue; benchmarks in 2002 have been performed based on US BWR-4 reference experimental data. Russian-designed VVER-1000 reactors have also been the subject of recent benchmark studies.

The NEA Data Bank services its member countries in regard to many requests for experimental and bibliographical nuclear data. Important improvements and updates are carried out through the joint evaluated fission and fusion (JEFF) activities. Data are available for ~ 340 different isotopes or elements including thermal scattering data for five lattice structures. The NEA is co-ordinating international collaboration among the major global nuclear data evaluation projects.

Experimental reactors are available for determining neutronic characteristics of reactor lattices, although the number of facilities is much less now in the world than hitherto. The EC is supporting the RENION project (Vasa, to be published) for carrying out PWR and VVER reactor physics related experiments.