Analysis of void experiments with a continuous energy, probabilistic methodology - 160

In the framework of a study on the feasibility of full Plutonium loading PWR cores, sponsored by COGEMA and currently carried out by FRAMATOME, a wide qualification of the Monte Carlo MCNP4 code with continuous-energy JEF2.2 library, in use at FRAMATOME for design and safety analysis, was undertaken. The qualification was also searched for intermediate and hard spectrum conditions, such as partial and full heterogeneous void. It was achieved both for reactivity and reaction rates on a 35-experiment basis including homogeneous and heterogeneous, Uranium, Plutonium and mixed fuel mock-ups. A wide selection of partial and full heterogeneous void configurations at 2 and 3D was included in the experimental basis for qualification. The paper shows that the MCNP4 code, with its reference JEF-2.2 library, is qualified for applications to very heterogeneous situations in space and energy, for all Plutonium enrichments and isotopic compositions in the design range. (author)