Nuclear Data for Reactor Physics: Cross sections and level densities in the actinide region

¹ Institut de Physique Nucleaire Orsay, bat. 100, 15 rue G. Clemenceau, 91406 Orsay cedex, France
² University in Oslo, Blindern, Sem Sælandsvei 24, 0317 Oslo, Norway
³ IRFU, Orme des Merisiers, bat. 703, 91191 Gif-Sur-Yvette cedex, France
⁴ CENBG Bordeaux, Chemin du Solarium - Le haut vigneau. BP 120, 33175 Gradignan Cedex, France
⁵ Lawrence Livermore National Laboratory 7000 East Avenue, Livermore, CA 94550, USA

^a e-mail: wilson@in2p3.fr

Abstract

Nuclear data in the actinide region are particularly important because they are basis behind all simulations of nuclear reactor core behaviour over both long time scales (fuel depletion and waste production) and short time scales (accident scenarios). Nuclear reaction cross sections must be known as precisely as possible so that core reaction rates can be accurately calculated. Although cross section measurements in this region have been widely performed, for certain nuclei, particularly those with short half lives, direct measurements are either very difficult or impossible and thus reactor simulations must rely on theoretical calculations or extrapolations from neighbouring nuclei. The greatest uncertainty in theoretical cross section calculations comes from the lack of knowledge of level densities, for which predicted values can often be incorrect by a factor of two or more. Therefore there is a strong case for a systematic experimental study of level densities in the actinide region for the purpose of a) providing a stringent test of theoretical cross section calculations for nuclei where experimental cross section data are available and b) for providing better estimations of cross sections for nuclei in which no cross section data are available.