Source uniform sampling in cell of given material

Shimwell · April 28, 2021, 7:18pm

I’ve raised an issue for this feature and put a bounty reward on it

Generic filter for rejecting sources points when sampling

opened 06:41PM - 28 Apr 21 UTC

bounty

As originally discussed on Discourse https://openmc.discourse.group/t/source-un…iform-sampling-in-cell-of-given-material/1062 It would be great to add generic filter to allow the rejection of source points when being sampled during the creation of particles. Source sampling should allow for rejection of the proposed sampled coordinates if the coordinates are not in a user specified material or not in a user specified cell. While the generic source sampling filter would be separate to the distributions themselves it could be passed to the distributions and the distributions should make use of the filter to ascertain if the sampling point results in a neutron or not. Perhaps the best distribution to demonstrate this on is the ```openmc.stats.Box``` distribution as it already has a similar feature. This will allow us to make interesting shaped sources like the example picture below which shows source sampling randomly across a openmc.stats.Box rejecting sample points that don't appear within a certain material / cell ![Screenshot from 2021-04-27 20-16-20](https://user-images.githubusercontent.com/8583900/116299325-73d16300-a795-11eb-8566-1cee34602f41.png) There are some related lines in OpenMC relating to a similar feature that allows sampling points to be rejected if they are not within a fissionable material with the ```only_fissionable``` keyword that might be useful for anyone considering this feature. https://github.com/openmc-dev/openmc/blob/efcc0c158edcc3e389eb20a5c5ffc4e0a65ef554/src/distribution_spatial.cpp#L187-L204 https://github.com/openmc-dev/openmc/blob/efcc0c158edcc3e389eb20a5c5ffc4e0a65ef554/src/source.cpp#L171-L173 https://github.com/openmc-dev/openmc/blob/efcc0c158edcc3e389eb20a5c5ffc4e0a65ef554/openmc/stats/multivariate.py#L617-L716

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Source uniform sampling in cell of given material

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