What’s New in 0.13.3


This release of OpenMC includes many bug fixes, performance improvements, and several notable new features. Some of the highlights include support for MCPL source files, NCrystal thermal scattering materials, and a new openmc.stats.MeshSpatial class that allows a source distribution to be specified over a mesh. Additionally, OpenMC now allows you to export your model as a single XML file rather than separate XML files for geometry, materials, settings, and tallies.

Compatibility Notes and Deprecations

  • Atomic mass data used in openmc.data.atomic_mass() has been updated to AME 2020, which results in slightly different masses.

New Features

Bug Fixes

  • Fix for finding redundant surfaces (#2263)

  • Adds tolerance for temperatures slightly out of bounds (#2265)

  • Fix getter/setter for weight window bounds (#2275)

  • Make sure Chain.reduce preserves decay source (#2283)

  • Fix array shape for weight window bounds (#2284)

  • Fix for non-zero CDF start points in TSL data (#2290)

  • Fix a case where inelastic scattering yield is zero (#2295)

  • Prevent Compton profile out-of-bounds memory access (#2297)

  • Produce light particles from decay (#2301)

  • Fix zero runtime attributes in depletion statepoints (#2302)

  • Fix bug in openmc.Universe.get_nuclide_densities (#2310)

  • Only show print output from depletion on rank 0 (#2311)

  • Fix photon transport with no atomic relaxation data (#2312)

  • Fix for precedence in region expressions (#2318)

  • Allow source particles with energy below cutoff (#2319)

  • Fix IncidentNeutron.from_njoy for high temperatures (#2320)

  • Add capability to unset cell temperatures (#2323)

  • Fix in plot_xs when S(a,b) tables are present (#2335)

  • Various fixes for tally triggers (#2344)

  • Raise error when mesh is flat (#2363)

  • Don’t call normalize inside Tabular.mean (#2375)

  • Avoid out-of-bounds access in inelastic scatter sampling (#2378)

  • Use correct direction for anisotropic fission (#2381)

  • Fix several thermal scattering nuclide assignments (#2382)

  • Fix _materials_by_id attribute in Model (#2385)

  • Updates to batch checks for simulation restarts (#2390)

  • write_data_to_vtk volume normalization correction (#2397)

  • Enable generation of JEFF 3.3 depletion chain (#2410)

  • Fix spherical to Cartesian coordinate conversion (#2417)

  • Handle zero photon cross sections in IncidentPhoton.from_ace (#2433)

  • Fix hybrid depletion when nuclides are not present (#2436)

  • Fix bug in cylindrical and spherical meshes (#2439)

  • Improvements to mesh radial boundary coincidence (#2443)