Build mapping to avoid O(N) lookup in FluxCollapseHelper.get_material_rates
Build mapping to avoid O(N) lookup in FluxCollapseHelper.get_material_rates

walshjon/openmc,walshjon/openmc,shikhar413/openmc,mit-crpg/openmc,walshjon/openmc,shikhar413/openmc,amandalund/openmc,paulromano/openmc,walshjon/openmc,amandalund/openmc,paulromano/openmc,shikhar413/openmc,amandalund/openmc,mit-crpg/openmc,mit-crpg/openmc,mit-crpg/openmc,amandalund/openmc,paulromano/openmc,paulromano/openmc,shikhar413/openmc