What’s New in 0.12.1

Summary

This release of OpenMC includes an assortment of new features and many bug fixes. The openmc.deplete module incorporates a number of improvements in usability, accuracy, and performance. Other enhancements include generalized rotational periodic boundary conditions, expanded source modeling capabilities, and a capability to generate windowed multipole library files from ENDF files.

New Features

• Boundary conditions have been refactored and generalized. Rotational periodic boundary conditions can now be applied to any N-fold symmetric geometry.

• External source distributions have been refactored and extended. Users writing their own C++ custom sources need to write a class that derives from openmc::Source. These changes have enabled new functionality, such as:

  • Mixing more than one custom source library together

  • Mixing a normal source with a custom source

  • Using a file-based source for fixed source simulations

  • Using a file-based source for eigenvalue simulations even when the number of particles doesn’t match

• New capability to read and write a source file based on particles that cross a surface (known as a “surface source”).

• Various improvements related to depletion:

  • Reactions used in a depletion chain can now be configured through the reactions argument to openmc.deplete.Chain.from_endf().

  • Specifying a power of zero during a depletion simulation no longer results in an unnecessary transport solve.

  • Reaction rates can be computed either directly or using multigroup flux tallies that are used to collapse reaction rates afterward. This is enabled through the reaction_rate_mode and reaction_rate_opts to openmc.deplete.Operator.

  • Depletion results can be used to create a new openmc.Materials object using the openmc.deplete.ResultsList.export_to_materials() method.

• Multigroup current and diffusion cross sections can be generated through the openmc.mgxs.Current and openmc.mgxs.DiffusionCoefficient classes.

• Added openmc.data.isotopes() function that returns a list of naturally occurring isotopes for a given element.

• Windowed multipole libraries can now be generated directly from the Python API using openmc.data.WindowedMultipole.from_endf().

• The new openmc.write_source_file() function allows source files to be generated programmatically.

Bug Fixes

• Proper detection of MPI wrappers

• Fix related to declaration order of maps/vectors

• Check for existence of decay rate attribute

• Small updates to deal with JEFF 3.3 data

• Fix for depletion chain generation

• Fix call to superclass constructor in MeshPlotter

• Fix for data crossover in VTK files

• Make sure reaction names are recognized as valid tally scores

• Fix bug related to logging of particle restarts

• Examine if region exists before removing redundant surfaces

• Fix plotting of individual universe levels

• Mixed materials should inherit depletable attribute

• Fix typo in energy units in dose coefficients

• Fixes for large tally cases

• Fix verification of volume calculation results

• Fix calculation of decay energy for depletion chains

• Fix pointers in CartesianIndependent

• Ensure correct initialization of members for RegularMesh

• Add missing import in depletion module

• Fixed several bugs related to decay-rate

• Fix how depletion operator distributes burnable materials

• Fix assignment of elemental carbon in JEFF 3.3

• Fix typo in RectangularParallelepiped.__pos__

• Fix temperature tolerance with S(a,b) data

• Fix sampling or normal distribution

• Fix for SharedArray relaxed memory ordering

• Check for proper format of source files

• Ensure (n,gamma) reaction rate tally uses sampled cross section

• Fix for temperature range behavior

Contributors

This release contains new contributions from the following people:

• Andrew Davis

• Guillaume Giudicelli

• Sterling Harper

• Bryan Herman

• Yue Jin

• Andrew Johnson

• Miriam Kreher

• Shikhar Kumar

• Jingang Liang

• Amanda Lund

• Adam Nelson

• April Novak

• YoungHui Park

• Ariful Islam Pranto

• Ron Rahaman

• Gavin Ridley

• Paul Romano

• Jonathan Shimwell

• Dan Short

• Patrick Shriwise

• Roy Stogner

• John Tramm

• Cyrus Wyett

• Jiankai Yu