Geometry-debug mode with DAGMCUniverse

User Support
1

Hi,

I created a CAD geometry and converted it into an h5m file using the Coreform Cubit program.

Afterward, I loaded it in OpenMC using the DAGMCUniverse like in the code below and created a larget CSG Cell which is filled with DAGMCUniverse.

hex_prism = openmc.model.HexagonalPrism(
            edge_length=my_length,
            origin=(0.0, 0.0),
            orientation='y',
            boundary_type='periodic'
        )

        z_min_plane = openmc.ZPlane(z0=my_z_neg, boundary_type='vacuum')
        z_max_plane = openmc.ZPlane(z0=my_z_pos, boundary_type='vacuum')

        final_region = -hex_prism & +z_min_plane & -z_max_plane # CSG Cell
        
       
        dag_universe = openmc.DAGMCUniverse(filename="my_h5m_file", auto_geom_ids=True)

        root_cell = openmc.Cell(
            name='root_cell',
            region=final_region,
            fill=dag_universe,
            cell_id=999
        )

        
        root_universe = openmc.Universe(cells=[root_cell])
        my_geometry = openmc.Geometry(root_universe)

In other words, the parts of the CSG Cell that don’t contain the DAGMCUniverse are treated as a vacuum (void).

When I run OpenMC in geometry-debug mode, the following error occurs:

ERROR: Overlapping cells detected: 1053, 1016 on universe 1

Once I check the geometry with openmc-plotter, cell 1053 is a void cell, and cell 1016 is the first cell of the DAGMCUniverse that a neutron starting in the void cell encounters.

The check_watertight and overlap_check functions provided by DAGMC passed without any issues.

What might be the problem?

(By the way, when I run the OpenMC without geometry-debug mode, it worked without any issues.)

2

Geometry debugging mode (cell overlap checks) don’t work for DAGMC geometries · Issue #3023 · openmc-dev/openmc