R. Jain and T. Tautges, "RGG: Reactor Geometry (&mesh) Generator," Preprint ANL/MCS-P2005-0612, June 2012. [pdf]
RGG takes advantage of information about repeated structures in both assembly and core lattices to simplify the creation of geometry and mesh, it is released as an open source software as a part of MeshKit mesh generation library. The methodology operates in three stages. First, assembly geometry models of various types are generated by a tool called AssyGen, next, the assembly model or models are meshed using MeshKit tools or the CUBIT mesh generation toolkit, optionally based on a journal file output by AssyGen. After one or more assembly model meshes have been constructed, they are arranged in a core model using a tool called CoreGen, it uses a copy/move/merge process to create the core model. In this paper, we present the current state of tools, new features and parallel-enabled CoreGen. CoreGen is ideally suited for parallelism, during creation of large reactor core models it was realized as a bottleneck in the process. For several problems speedups for CoreGen are super-linear, due to the problem fitting in available RAM at higher processor counts. Several RGG applications viz. VHTR models, a one-fourth PWR reactor core, and a Full Core model for MONJU are reported.