recent progess in the vetv of the french apollo3 code 3d full core analysis of the uh1.2 integral experiment using idtmethod of characteristics

Within the framework of the VetV of the new APOLLO3 French deterministic code, this paper focusses on its ability of analyzing integral mock-up experiments through IDT flux solver. In the present case, the UH1.2 experiments involving voiding effects in standard PWR UOX lattices are investigated through straightforward 281 groups 3D transport calculations using recent capabilities of IDT solver based on Sn short-characteristics method. Instead of using standard 2D calculations with imposed experimental et119861;et119911;2we performed directly 3D 281 groups IDT calculations and checked the results against reference continuous-energy Monte-Carlo (TRIPOLI4) results in a simplified axial configuration. In both cases the IDT solver (with dedicated self-shielding model) shows an excellent agreement with Monte-Carlo results regarding both reactivity and fission rate reference parameters. In particular it is shown that linear short characteristics and refined spatial meshes (3x3x1) are necessary to find the best agreement (less than 1percent fission rate and void effect errors). The next step of this work will be devoted to the analysis of the 3D TDT-MOC solver in the same configurations with ad-hoc axial reflector treatment. To remove the limitations in terms of CPU time and memory resources of this kind of calculations, ongoing developments devoted to hybrid shared/distributed parallelization (OpenMP/MPI) are also pointed out.