NARMER-1: a photon point-kernel code with build-up factors

This paper presents an overview of NARMER-1, the new generation of photon point-kernel code developed by the Reactor Studies and Applied Mathematics Unit (SERMA) at CEA Saclay Center. After a short introduction giving some history points and the current context of development of the code, the paper exposes the principles implemented in the calculation, the physical quantities computed and surveys the generic features: programming language, computer platforms, geometry package, sources description, etc. Moreover, specific and recent features are also detailed: exclusion sphere, tetrahedral meshes, parallel operations. Then some points about verification and validation are presented. A validation study has been done with comparison to TRIPOLI-4 considered as a reference Monte-Carlo code. Basic configurations and sophisticated configurations show overall a good agreement between the two codes. In some cases, we observe an overestimation of NARMER-1 with respect to TRIPOLI-4. The results are conservative for radiation protection studies and NARMER-1 calculations are much faster than TRIPOLI-4 ones. Finally we present some tools that can help the user for operations like visualization and pre-treatment