0.14.0.rst

What's New in 0.14.0

.. currentmodule:: openmc

Summary

This release of OpenMC includes many bug fixes, performance improvements, and several notable new features. Some of the highlights include projection plots, pulse height tallies for photons, weight window generation, and an ability to specify continuous removal or feed of nuclides/elements during depletion. Additionally, one of the longstanding annoyances of depletion calculations, namely the need to include initial "dilute" nuclides, has been eliminated. There are also a wide array of general improvements in the Python API.

Compatibility Notes and Deprecations

• The :class:`openmc.deplete.MicroXS` has been completely redesigned and improved. See further comments below under "New Features". (#2572, #2579, #2595, #2700)
• The rectangular_prism function has been replaced by the :class:`openmc.model.RectangularPrism` class and the hexagonal_prism function has been replaced by the :class:`openmc.model.HexagonalPrism` class. Note that whereas the rectangular_prism and hexagonal_prism functions returned a region representing the interior of the prism, the new :class:`~openmc.model.RectangularPrism` and :class:`~openmc.model.HexagonalPrism` classes return composite surfaces, so you need to use the unary - or + operators to obtain a region that can be assigned to a cell. (#2739)
• The Source class has been refactored and split up into three separate classes: :class:`~openmc.IndependentSource`, :class:`~openmc.FileSource`, and :class:`~openmc.CompiledSource`. (#2524)
• The vertices and centroids attributes on mesh classes now always return Cartesian coordinates and the shape of the returned arrays has changed to allow ijk indexing using a tuple (i.e., xyz = vertices[i, j, k]). (#2711)
• The :attr:`openmc.Material.decay_photon_energy` attribute has been replaced by the :meth:`openmc.Material.get_decay_photon_energy` method. (#2715)

New Features

• A new :class:`openmc.ProjectionPlot` class enables the generation of orthographic or perspective projection plots. (#1926)
• The :class:`openmc.model.RightCircularCylinder` class now supports optional filleted edges. (#2309)
• Continuous removal or feed of nuclides/elements between materials can now be modeled during depletion via the :meth:`openmc.deplete.abc.Integrator.add_transfer_rate` method. (#2358, #2564, #2626)
• The MAGIC method for global weight window generation has been implemented as part of the C++ API. (#2359)
• A new capability for pulse height tallies (currently limited to photons) has been added and can be used via the "pulse-height" tally score. (#2452)
• A :class:`openmc.model.CruciformPrism` class has been added that provides a generalized cruciform prism composite surface. (#2457)
• Type hints have been added in various places throughout the Python API. (#2462, #2467, #2468, #2470, #2471, #2601)
• Voxel plots can now be generated through the :meth:`openmc.Plot.to_vtk` method. (#2464)
• The :class:`openmc.mgxs.EnergyGroups` class now allows you to alternatively pass a string of the group structure name (e.g., "CCFE-709") instead of the energy group boundaries. (#2466)
• Several enhancements have been made to the :meth:`openmc.Universe.plot` method (addition of axis labels with units, ability to show legend and/or outlines, automatic determination of origin/width, ability to pass total number of pixels). (#2472, #2482, #2483, #2492, #2513, #2575)
• Functionality in the Python dealing with bounding boxes now relies on a new :class:`openmc.BoundingBox` class. (#2475)
• Users now have more flexibility in specifying nuclides and reactions in the :func:`openmc.plot_xs` function. (#2478)
• The import time of the :mod:`openmc` Python module has been improved by deferring the import of matplotlib. (#2488)
• Mesh clases in the Python API now support a bounding_box property. (#2507, #2620, #2621)
• The Source class has been refactored and split up into three separate classes: :class:`~openmc.IndependentSource`, :class:`~openmc.FileSource`, and :class:`~openmc.CompiledSource`. (#2524)
• Support was added for curvilinear elements when exporting cylindrical and spherical meshes to VTK. (#2533)
• The :class:`openmc.Tally` class now has a :attr:`~openmc.Tally.multiply_density` attribute that indicates whether reaction rate tallies should include the number density of the nuclide of interest. (#2539)
• The :func:`~openmc.wwinp_to_wws` function now supports wwinp files with cylindrical or spherical meshes. (#2556)
• Depletion no longer relies on adding initial "dilute" nuclides to each depletable material in order to compute reaction rates. (#2559, #2568)
• The :class:`openmc.deplete.Results` class now has :meth:`~openmc.deplete.Results.get_mass` (#2565), :meth:`~openmc.deplete.Results.get_activity` (#2617), and :meth:`~openmc.deplete.Results.get_decay_heat` (#2625) methods.
• The :meth:`openmc.deplete.StepResult.save` method now supports a path argument. (#2567)
• The :class:`openmc.deplete.MicroXS` has been completely redesigned and improved. First, it no longer relies on the :mod:`openmc.mgxs` module, no longer subclasses :class:`pandas.DataFrame`, and doesn't require adding initial "dilute" nuclides into material compositions. It now enables users to specify an energy group structure to collect multigroup cross sections, specify nuclides/reactions, and works with mesh domains in addition to the existing domains. A new :func:`openmc.deplete.get_microxs_and_flux` function was added that improves the workflow for calculating microscopic cross sections along with fluxes. Altogether, these changes make it straightforward to switch between coupled and independent operators for depletion/activation calculations. (#2572, #2579, #2595, #2700)
• The :class:`openmc.Geometry` class now has merge_surfaces and surface_precision arguments. (#2602)
• Several predefined energy group structures have been added ("MPACT-51", "MPACT-60", "MPACT-69", "SCALE-252"). (#2614)
• When running a depletion calculation, you are now allowed to include nuclides in the initial material compositions that do not have neutron cross sections (decay-only nuclides). (#2616)
• The :class:`~openmc.CylindricalMesh` and :class:`~openmc.SphericalMesh` classes can now be fully formed using the constructor. (#2619)
• A time cutoff can now be specified in the :attr:`openmc.Settings.cutoff` attribute. (#2631)
• The :meth:`openmc.Material.add_element` method now supports a cross_sections argument that allows a cross section data source to be specified. (#2633)
• The :class:`~openmc.Cell` class now has a :meth:`~openmc.Cell.plot` method. (#2648)
• The :class:`~openmc.Geometry` class now has a :meth:`~openmc.Geometry.plot` method. (#2661)
• When weight window checks are performed can now be explicitly specified with the :attr:`openmc.Settings.weight_window_checkpoints` attribute. (#2670)
• The :class:`~openmc.Settings` class now has a :attr:`~openmc.Settings.max_write_lost_particles` attribute that can limit the number of lost particle files written. (#2688)
• The :class:`~openmc.deplete.CoupledOperator` class now has a diff_volume_method argument that specifies how the volume of new materials should be determined. (#2691)
• The :meth:`openmc.DAGMCUniverse.bounding_region` method now has a padding_distance argument. (#2701)
• A new :meth:`openmc.Material.get_decay_photon_energy` method replaces the :attr:`decay_photon_energy` attribute and includes an ability to eliminate low-importance points. This is facilitated by a new :meth:`openmc.stats.Discrete.clip` method. (#2715)
• The :meth:`openmc.model.Model.differentiate_depletable_mats` method allows depletable materials to be differentiated independent of the depletion calculation itself. (#2718)
• Albedos can now be specified on surface boundary conditions. (#2724)

Bug Fixes

• Enable use of NCrystal materials in plot_xs (#2435)
• Avoid segfault from extern "C" std::string (#2455)
• Fix several issues with the Model class (#2465)
• Provide alternative batch estimation message (#2479)
• Correct index check for remove_tally (#2494)
• Support for NCrystal material in from_xml_element (#2496)
• Fix compilation with gcc 5 (#2498)
• Fixed in the Tally::add_filter method (#2501)
• Fix meaning of "masking" for plots (#2510)
• Fix description of statepoint.batches in Settings class (#2514)
• Reorder list initialization of Plot constructor (#2519)
• Added mkdir to cwd argument in Model.run (#2523)
• Fix export of spherical coordinates in SphericalMesh (#2538)
• Add virtual destructor on PlottableInterface (#2541)
• Ensure parent directory is created during depletion (#2543)
• Fix potential out-of-bounds access in TimeFilter (#2532)
• Remove use of sscanf for reading surface coefficients (#2574)
• Fix torus intersection bug (#2589)
• Multigroup per-thread cache fixes (#2591)
• Bank surface source particles in all active cycles (#2592)
• Fix for muir standard deviation (#2598)
• Check for zero fission cross section (#2600)
• XML read fixes in Plot classes (#2623)
• Added infinity check in VolumeCalculation (#2634)
• Fix sampling issue in Mixture distributions (#2658)
• Prevent segfault in distance to boundary calculation (#2659)
• Several CylindricalMesh fixes (#2676, #2680, #2684, #2710)
• Add type checks on Intersection, Union, Complement (#2685)
• Fixed typo in CF4Integrator docstring (#2704)
• Ensure property setters are used in CylindricalMesh and SphericalMesh (#2709)
• Fix sample_external_source bug (#2713)
• Fix localization issue affecting openmc-plotter (#2723)
• Correct openmc.lib wrapper for evaluate_legendre (#2729)
• Bug fix in Region.from_expression during tokenization (#2733)
• Fix bug in temperature interpolation (#2734)
• Check for invalid domain IDs in volume calculations (#2742)
• Skip boundary condition check for volume calculations (#2743)
• Fix loop over coordinates for source domain rejection (#2751)

Contributors

• April Novak
• Baptiste Mouginot
• Ben Collins
• Chritopher Billingham
• Christopher Fichtlscherer
• Christina Cai
• Lorenzo Chierici
• Huw Rhys Jones
• Emilio Castro
• Erik Knudsen
• Ethan Peterson
• Egor Afanasenko
• Paul Wilson
• Gavin Ridley
• Hunter Belanger
• Jack Fletcher
• John Vincent Cauilan
• Josh May
• John Tramm
• Kevin McLaughlin
• Yue Jin
• Lewis Gross
• Luke Labrie-Cleary
• Patrick Myers
• Nicola Rizzi
• Yuvraj Jain
• Paul Romano
• Patrick Shriwise
• Rosie Barker
• Jonathan Shimwell
• John Tchakerian
• Travis Labossiere-Hickman
• Xinyan Wang
• Olek Yardas
• Zoe Prieto