An analysis of first flight collision probability method's performances in 3D geometry

The first flight collision probability (FFCP) is a powerful method to obtain effective cross-sections at cell level in reactor physics. However, the computing time and the memory requirements increase rapidly with the number of discrete regions. The paper gives an analysis of the potential sources to reduce these disadvantages. On this basis some methods and algorithms has been developed to improve the performances of the 3D integral transport code PIJXYZ. Finally, the new version PIJXYZ2.0 has a 50% reducing in memory requirements and a 3-5 times decreasing of computing time. (authors)