Support for OpenMC's random ray solver in Cardinal #1273
Description
Reason
The Random Ray Method (TRRM) is a fast-running alternative to the continuous energy / multi-group Monte Carlo solvers presently supported in Cardinal's OpenMC wrapper. TRRM offers several advantages over multi-group Monte Carlo, such as: uniform relative error distributions over the entire computational domain, neutron kinetics (openmc-dev/openmc#3702), and MPI domain decomposition (should be implemented soon, see openmc-dev/openmc#3009). TRRM in OpenMC also supports adjoint flux calculations.
There are many interesting research area that would be enabled by wrapping TRRM in Cardinal. Of interest to Cardinal's userbase is a fast-running deterministic-adjacent solver for rapid multiphysics calculations.
Design
Wrapping TRRM in Cardinal is quite straight-forward, a proof-of-concept implementation can be found in this branch in my Cardinal fork. To support a minimum viable implementation for multiphysics, the following features need to be added in OpenMC:
- Tallies for fission heating / kappa-fission. Completed.
- Cell density feedback. Completed.
- Cell temperature feedback. Awaiting a merge into OpenMC.
TRRM is a multi-group deterministic-adjacent method, and so several Cardinal features cannot be supported by this solver. mooseErrors or paramErrors will need to be added to said features to disable them in running with TRRM. This accounts for the vast majority of the code additions in my proof-of-concept implementation.
Impact
New neutronics solver option for rapid multiphysics calculations.