We've moved:  http://sigma.mcs.anl.gov/meshkit-library/rgg/

RGG : Reactor Geometry (and mesh) Generator

RGG is an open source tool to generate several types nuclear reactor assembly/core geometry and mesh.

Some of the newer models created using RGG are highlighted on our new page:  https://collab.mcs.anl.gov/display/moab/Mesh+Locker


RGG consists of two tools:

1. Assygen: Generates a nuclear reactor assembly geometry and Cubit journal file to mesh this assembly.

A reactor assembly is described via a user defined input file that Assygen understands.

Step 1 & 2: Generating assembly geometry and meshing

Assygen input for the hexagonal assembly shown above can be found in the examples directory of the rgg source code. Assygen_input

2. Coregen: Takes assembly geometries or meshes as input and copy/move/merge 's them into core as specified in the Coregen input file.

Step 3: Copy-move-merge-extrude assemblies and other mesh files to form the core mesh

Run 'make' and seemakefile to generate the core model (Coregen_input.) shown above and understand the dependencies.


There are several tailor made test examples that can be run from the directory containing that test.

Users can run 'make' for creating all the assembly geometry files, all the assembly mesh files and the final core mesh in that test directory.

Some of the core models generated using RGG are presented below:

* Coupled Thermal-Irradiation-Structural Analysis of HGTR Fuel Brick Using ABAQUS *

Assygen and CUBIT were used in generating the models for this structural analysis. Axial and radial mesh size APREPRO variables in the template journal file created by Assygen were modified to create the desired mesh quality. The material considered is H-451 transversely isotropic graphite. At the end of 4.6 years radiation profile and inplane stress profile are shown. This assembly is located on the x-axis at a distance of 195.67cm from the center of core.


The details about the radiation and stress plots can be found on the ICAPP'12 paper: "Coupled Thermal-Irradiation-Structural Analysis of HGTR Fuel Brick Using ABAQUS".


Assygen is capable of creating assemblies with varying properties in axial and radial direction. Coregen is designed to operate in parallel allowing the core creation, merging of nodes and saving the mesh file in parallel.

MONJU reactor core mesh

This mesh, which uses 101 million volume elements to describe the reactor core, was generated by SHARP simulation tools in as little as seven minutes.

* PWR *

The benchmark problem: “MOX Fuel Loaded Small PWR Core” can be found on the website of Nuclear Reactor Analysis and Particle Transport Lab:


1/4th PWR benchmark assembly consisting of 11,000 volumes takes 25mins and 0.9GB of RAM on a Linux workstation.

* VHTR *

Full VHTR core mesh and geometry models can be created using RGG tools.

The mesh model has 21M hexes, it takes 96mins (serial run) and 3.5GB of RAM to generate the all assemblies and core mesh from scratch.

For this mesh model axial mesh interval (Z-direction) of 2 is used. The geometry model has ~33,000 volumes.

Isometric view of full VHTR core geometry (left), zoomed cross-sectional view of the top surface (center), further zoomed view of assemblies (right).

1/6th VHTR core geometry (left), closeup view of mesh (center), 1/12th VHTR core geometry (right).