Determining Neutron Current Through a Reflector

User Support
1

I have created a 1/4 core with reflective boundary conditions on the top and left, and vacuum at the O.D. of the reflector (everything else is transmissive).

I am trying to develop a tally that determines the reflector current through the reflector thickness. I am running into errors using the openmc.surfacefilter. Is there a standard method for generating this type of tally where the mesh is Cartesian but the geometry is circular?

Thanks

2

I have attached the notebook and I am following the methods from:

http://openmc.readthedocs.io/en/stable/examples/mdgxs-part-ii.html#Using-Tally-Arithmetic-to-Compute-the-Delayed-Neutron-Precursor-Concentrations

I am returning the dataframe below. The numbers in the dataframe do not seem to change if I modify the reflector thickness.

Project Reactor Core Geometry-Beryllium-Post Discussion.ipynb (276 KB)

3

Hello All,

I’d like to bump this as Jason is a student in my class and neither of us can figure it out and the documentation is not clear.

Be Well
Anthony

4

Hi Anthony and Jason,

The issue is that (for historical reasons) surface filters were primarily used for scoring currents on the surfaces of a regular mesh. However, at some point, we added the ability to get currents on a normally-defined (non-mesh) surface (using a SurfaceFilter). Because the surface filter was “overloaded” for two purposes, this led to strange bugs and confusion. In the develop branch, we’ve actually introduced a new filter (MeshSurfaceFilter) that specifically allows a user to get currents on a mesh surface, and SurfaceFilter is specifically for tallying surface-crossing events. Unfortunately, the best advice I can give you is to wait until the next release or live on the bleeding edge and checkout the develop branch.

Best regards,
Paul

5

Hi Paul,

Thanks for letting us know. For purposes of this class, I don’t think waiting is really an option and we’ll have to figure something else out.

Be Well

Anthony