====================
What's New in 0.13.2
====================

.. currentmodule:: openmc

-------
Summary
-------

This release of OpenMC includes several bug fixes, performance improvements for
complex geometries and depletion simulations, and other general enhancements.
Notably, a capability has been added to compute the photon spectra from decay of
unstable nuclides. Alongside that, a new :data:`openmc.config` configuration
variable has been introduced that allows easier configuration of data sources.
Additionally, users can now perform cell or material rejection when sampling
external source distributions.

------------------------------------
Compatibility Notes and Deprecations
------------------------------------

- If you are building against libMesh for unstructured mesh tally support,
  version 1.6 or higher is now required.
- The ``openmc.stats.Muir`` class has been replaced by a
  :func:`openmc.stats.muir` function that returns an instance of
  :class:`openmc.stats.Normal`.

------------
New Features
------------

- The :meth:`openmc.Material.get_nuclide_atom_densities` method now takes an
  optional ``nuclide`` argument.
- Functions/methods in the :mod:`openmc.deplete` module now accept times in
  Julian years (``'a'``).
- The :meth:`openmc.Universe.plot` method now allows a pre-existing axes object
  to be passed in.
- Performance optimization for geometries with many complex regions.
- Performance optimization for depletion by avoiding deepcopies and caching
  reaction rates.
- The :class:`openmc.RegularMesh` class now has a
  :meth:`~openmc.RegularMesh.from_domain` classmethod.
- The :class:`openmc.CylindricalMesh` class now has a
  :meth:`~openmc.CylindricalMesh.from_domain` classmethod.
- Improved method to condense diffusion coefficients from the :mod:`openmc.mgxs`
  module.
- A new :data:`openmc.config` configuration variable has been introduced that
  allows data sources to be specified at runtime or via environment variables.
- The :class:`openmc.EnergyFunctionFilter` class now supports multiple
  interpolation schemes, not just linear-linear interpolation.
- The :class:`openmc.DAGMCUniverse` class now has ``material_names``,
  ``n_cells``, and ``n_surfaces`` attributes.
- A new :func:`openmc.data.decay_photon_energy` function has been added that
  returns the energy spectrum of photons emitted from the decay of an unstable
  nuclide.
- The :class:`openmc.Material` class also has a new
  :attr:`~openmc.Material.decay_photon_energy` attribute that gives the decay
  photon energy spectrum from the material based on its constituent nuclides.
- The :class:`openmc.deplete.StepResult` now has a
  :meth:`~openmc.deplete.StepResult.get_material` method.
- The :class:`openmc.Source` class now takes a ``domains`` argument that
  specifies a list of cells, materials, or universes that is used to reject
  source sites (i.e., if the sampled sites are not within the specified domain,
  they are rejected).

---------
Bug Fixes
---------

- `Delay call to Tally::set_strides <https://github.com/openmc-dev/openmc/pull/2183>`_
- `Fix reading reference direction from XML for angular distributions <https://github.com/openmc-dev/openmc/pull/2204>`_
- `Fix erroneous behavior in Material.add_components <https://github.com/openmc-dev/openmc/pull/2205>`_
- `Fix reading thermal elastic data from ACE <https://github.com/openmc-dev/openmc/pull/2226>`_
- `Fix reading source file with time attribute <https://github.com/openmc-dev/openmc/pull/2228>`_
- `Fix conversion of multiple thermal scattering data files from ACE <https://github.com/openmc-dev/openmc/pull/2232>`_
- `Fix reading values from wwinp file <https://github.com/openmc-dev/openmc/pull/2242>`_
- `Handle possibility of .ppm file in Universe.plot <https://github.com/openmc-dev/openmc/pull/2251>`_
- `Update volume calc types to mitigate overflow issues <https://github.com/openmc-dev/openmc/pull/2270>`_

------------
Contributors
------------

- `Lewis Gross <https://github.com/lewisgross1296>`_
- `Andrew Johnson <https://github.com/drewejohnson>`_
- `Miriam Kreher <https://github.com/mkreher13>`_
- `James Logan <https://github.com/jlogan03>`_
- `Jose Ignacio Marquez Damien <https://github.com/marquezj>`_
- `Josh May <https://github.com/joshmay1>`_
- `Patrick Myers <https://github.com/myerspat>`_
- `Adam Nelson <https://github.com/nelsonag>`_
- `April Novak <https://github.com/aprilnovak>`_
- `Ethan Peterson <https://github.com/eepeterson>`_
- `Gavin Ridley <https://github.com/gridley>`_
- `Paul Romano <https://github.com/paulromano>`_
- `Patrick Shriwise <https://github.com/pshriwise>`_
- `Jonathan Shimwell <https://github.com/Shimwell>`_
- `Olek Yardas <https://github.com/yardasol>`_