paulromano · Aug 5, 2026 · Aug 3, 2026 · Aug 3, 2026 · Aug 4, 2026 · Aug 4, 2026
diff --git a/docs/source/pythonapi/base.rst b/docs/source/pythonapi/base.rst
@@ -21,6 +21,7 @@ Simulation Settings
    :nosignatures:
    :template: myclass.rst
 
+   openmc.ParticleType
    openmc.SourceBase
    openmc.IndependentSource
    openmc.FileSource

diff --git a/docs/source/pythonapi/capi.rst b/docs/source/pythonapi/capi.rst
@@ -42,6 +42,9 @@ Functions
    run_in_memory
    run_random_ray
    sample_external_source
+   slice_data
+   slice_data_overlap_count
+   slice_data_overlap_info
    simulation_finalize
    simulation_init
    source_bank

diff --git a/docs/source/pythonapi/examples.rst b/docs/source/pythonapi/examples.rst
@@ -10,6 +10,8 @@ Simple Models
    :nosignatures:
    :template: myfunction.rst
 
+   openmc.examples.random_ray_pin_cell
+   openmc.examples.random_ray_three_region_cube_with_detectors
    openmc.examples.slab_mg
    openmc.examples.sphere_with_shielded_pocket
 

diff --git a/docs/source/releasenotes/0.16.0.rst b/docs/source/releasenotes/0.16.0.rst
diff --git a/docs/source/releasenotes/index.rst b/docs/source/releasenotes/index.rst
@@ -7,6 +7,7 @@ Release Notes
 .. toctree::
   :maxdepth: 1
 
+  0.16.0
   0.15.3
   0.15.2
   0.15.1

@@ -317,7 +317,7 @@ def half_life(
 
     .. versionadded:: 0.13.1
 
-    .. versionchanged:: 0.15.4
+    .. versionchanged:: 0.16.0
         Added the ``chain_file`` argument.
 
     Parameters
@@ -367,7 +367,7 @@ def decay_constant(
 
     .. versionadded:: 0.13.1
 
-    .. versionchanged:: 0.15.4
+    .. versionchanged:: 0.16.0
         Added the ``chain_file`` argument.
 
     Parameters

@@ -105,6 +105,8 @@ def mass_energy_absorption_coefficient(
     from `NIST Standard Reference Database 126
     <https://doi.org/10.18434/T4D01F>`_: X-Ray Mass Attenuation Coefficients.
 
+    .. versionadded:: 0.16.0
+
     Parameters
     ----------
     material : str or int
@@ -162,6 +164,8 @@ def mass_attenuation_coefficient(element):
     Reference Database 8 <https://doi.org/10.18434/T48G6X>`_: XCOM Photon Cross
     Sections Database.
 
+    .. versionadded:: 0.16.0
+
     Parameters
     ----------
     element : str or int

@@ -577,7 +577,7 @@ class Integrator(ABC):
         factorizations may be reused across them, improving accuracy for
         nuclides with large decay-constant × timestep products.
 
-        .. versionadded:: 0.15.4
+        .. versionadded:: 0.16.0
     continue_timesteps : bool, optional
         Whether or not to treat the current solve as a continuation of a
         previous simulation. Defaults to `False`. When `False`, the depletion
@@ -1192,7 +1192,7 @@ def add_keff_search_control(
         ...>
         ... )
 
-        .. versionadded:: 0.15.4
+        .. versionadded:: 0.16.0
 
         """
         self._keff_search_control = _KeffSearchControl(
@@ -1256,7 +1256,7 @@ class SIIntegrator(Integrator):
         factorizations may be reused across them, improving accuracy for
         nuclides with large decay-constant × timestep products.
 
-        .. versionadded:: 0.15.4
+        .. versionadded:: 0.16.0
     continue_timesteps : bool, optional
         Whether or not to treat the current solve as a continuation of a
         previous simulation. Defaults to `False`. If `False`, all time steps and

@@ -137,7 +137,7 @@ def get_activity(
             ``None`` or an explicit chain, nuclides absent from the chain fall
             back to ENDF/B-VIII.0 data.
 
-            .. versionadded:: 0.15.4
+            .. versionadded:: 0.16.0
 
         Returns
         -------

diff --git a/openmc/examples.py b/openmc/examples.py
@@ -876,6 +876,8 @@ def random_ray_pin_cell(second_temp = False) -> openmc.Model:
     """Create a PWR pin cell example using C5G7 cross section data.
     cross section data.
 
+    .. versionadded:: 0.16.0
+
     Parameters
     ----------
     second_temp : bool, optional
@@ -1327,6 +1329,8 @@ def random_ray_three_region_cube_with_detectors() -> openmc.Model:
     region. The model returned by this function contains cell tallies on each
     detector.
 
+    .. versionadded:: 0.16.0
+
     Returns
     -------
     model : openmc.Model
@@ -1624,6 +1628,8 @@ def fill_cube(N, n_1, n_2, fill_1, fill_2, fill_3):
 def sphere_with_shielded_pocket() -> openmc.Model:
     """Create a continuous energy deep-shielding model with a far detector pocket.
 
+    .. versionadded:: 0.16.0
+
     A concrete sphere is centered at the origin. A 2 MeV isotropic neutron
     source sits in a small air cavity just inside the sphere surface on the -x
     side, and a small steel pocket is embedded flush with the surface on the

diff --git a/openmc/filter.py b/openmc/filter.py
@@ -1404,7 +1404,7 @@ def check_bins(self, bins):
 class ReactionFilter(Filter):
     """Bins tally events based on the reaction type (MT number).
 
-    .. versionadded:: 0.15.4
+    .. versionadded:: 0.16.0
 
     Parameters
     ----------
@@ -1821,7 +1821,7 @@ class ParticleProductionFilter(Filter):
 
     The incident particle type can be filtered using :class:`ParticleFilter`.
 
-    .. versionadded:: 0.15.4
+    .. versionadded:: 0.16.0
 
     Parameters
     ----------

@@ -486,6 +486,8 @@ def run(output=True):
 def run_random_ray(output=True):
     """Run a random ray simulation
 
+    .. versionadded:: 0.16.0
+
     Parameters
     ----------
     output : bool, optional

@@ -609,6 +609,12 @@ def bins(self):
 
 
 class ParticleProductionFilter(Filter):
+    """Filter secondary-particle production events.
+
+    .. versionadded:: 0.16.0
+
+    """
+
     filter_type = 'particleproduction'
 
 
@@ -617,6 +623,12 @@ class PolarFilter(Filter):
 
 
 class ReactionFilter(Filter):
+    """Filter tally events by reaction type.
+
+    .. versionadded:: 0.16.0
+
+    """
+
     filter_type = 'reaction'
 
 

@@ -91,6 +91,8 @@ def slice_data(origin, width=None, basis='xy', u_span=None, v_span=None,
                 include_properties=True):
     """Generate a 2D raster of geometry and property data for plotting.
 
+    .. versionadded:: 0.16.0
+
     Parameters
     ----------
     origin : sequence of float
@@ -274,6 +276,8 @@ def property_map(plot):
 def slice_data_overlap_count() -> int:
     """Return the number of unique overlaps from the last slice plot.
 
+    .. versionadded:: 0.16.0
+
     Returns
     -------
     int
@@ -288,6 +292,8 @@ def slice_data_overlap_count() -> int:
 def slice_data_overlap_info() -> np.ndarray:
     """Return identifying information for overlaps from the last slice plot.
 
+    .. versionadded:: 0.16.0
+
     Returns
     -------
     numpy.ndarray
@@ -432,6 +438,8 @@ class SolidRayTracePlot(_FortranObjectWithID):
     the OpenMC library. To obtain a view of an existing plot with a given ID,
     use the :data:`openmc.lib.plots` mapping.
 
+    .. versionadded:: 0.16.0
+
     Parameters
     ----------
     uid : int or None

diff --git a/openmc/material.py b/openmc/material.py
@@ -1421,7 +1421,7 @@ def get_activity(
             ``None`` or an explicit chain, nuclides absent from the chain fall
             back to ENDF/B-VIII.0 data.
 
-            .. versionadded:: 0.15.4
+            .. versionadded:: 0.16.0
 
         Returns
         -------

diff --git a/openmc/mesh.py b/openmc/mesh.py
@@ -1514,7 +1514,7 @@ def build_cells(self, bc: str | None = None):
     def get_indices_at_coords(self, coords: Sequence[float]) -> tuple:
         """Finds the index of the mesh element at the specified coordinates.
 
-        .. versionadded:: 0.15.4
+        .. versionadded:: 0.16.0
 
         Parameters
         ----------
@@ -1768,7 +1768,7 @@ def to_xml_element(self):
     def get_indices_at_coords(self, coords: Sequence[float]) -> tuple[int, int, int]:
         """Find the mesh cell indices containing the specified coordinates.
 
-        .. versionadded:: 0.15.4
+        .. versionadded:: 0.16.0
 
         Parameters
         ----------
@@ -2665,7 +2665,7 @@ def get_indices_at_coords(
     ) -> tuple[int, int, int]:
         """Find the mesh cell indices containing the specified coordinates.
 
-        .. versionadded:: 0.15.4
+        .. versionadded:: 0.16.0
 
         Parameters
         ----------

diff --git a/openmc/mgxs/groups.py b/openmc/mgxs/groups.py
@@ -310,7 +310,7 @@ def convert_flux_groups(flux, source_groups, target_groups):
     unit lethargy within each source group and distributes flux to target
     groups proportionally to their lethargy width.
 
-    .. versionadded:: 0.15.4
+    .. versionadded:: 0.16.0
 
     Parameters
     ----------
@@ -348,8 +348,9 @@ def convert_flux_groups(flux, source_groups, target_groups):
     -----
     The assumption of constant flux per unit lethargy within each source
     group is physically reasonable for most reactor spectra but is not
-    exact. For best accuracy, use source spectra with sufficiently fine
-    energy resolution.
+    exact [1]_. For best accuracy, use source spectra with sufficiently fine
+    energy resolution. A similar group-conversion approach is available in
+    FISPACT-II [2]_.
 
     Examples
     --------

diff --git a/openmc/model/model.py b/openmc/model/model.py
@@ -24,7 +24,7 @@
 from openmc.checkvalue import (check_type, check_value, check_greater_than,
                                check_length, PathLike)
 from openmc.exceptions import InvalidIDError
-from openmc.plots import add_plot_params, _BASIS_INDICES, id_map_to_rgb
+from openmc.plots import add_plot_params, _BASIS_INDICES, _id_map_to_rgb
 from openmc.utility_funcs import change_directory, set_xml_input_path
 
 
@@ -1399,7 +1399,7 @@ def plot(
             colors = plot.colors
 
         # Convert ID map to RGB image
-        img = id_map_to_rgb(
+        img = _id_map_to_rgb(
             id_map=id_map,
             color_by=color_by,
             colors=colors,
@@ -2677,7 +2677,7 @@ def convert_to_multigroup(
             Number of particles to simulate per batch when generating MGXS.
             Defaults to 2000.
 
-            .. deprecated:: 0.15.4
+            .. deprecated:: 0.16.0
                 Pass ``particles`` as a keyword argument instead.
         overwrite_mgxs_library : bool, optional
             Whether to overwrite an existing MGXS library file.
@@ -2713,7 +2713,7 @@ def convert_to_multigroup(
             Valid entries for temperature_settings are the same as the valid
             entries in openmc.Settings.temperature_settings.
 
-            .. deprecated:: 0.15.4
+            .. deprecated:: 0.16.0
                 Pass ``temperature`` as a keyword argument instead.
         **kwargs
             :class:`openmc.Settings` attributes used to customize the continuous
@@ -2730,7 +2730,7 @@ def convert_to_multigroup(
             enables. Cannot be combined with the deprecated ``nparticles`` or
             ``temperature_settings`` arguments.
 
-            .. versionadded:: 0.15.4
+            .. versionadded:: 0.16.0
         """
         if not isinstance(groups, openmc.mgxs.EnergyGroups):
             groups = openmc.mgxs.EnergyGroups(groups)

diff --git a/openmc/particle_type.py b/openmc/particle_type.py
@@ -46,6 +46,10 @@ class ParticleType:
     to uniquely identify particle types. This includes elementary particles
     (neutrons, photons, etc.) and nuclear codes for isotopes.
 
+    .. versionchanged:: 0.16.0
+        Changed from an ``IntEnum`` to a class backed by PDG Monte Carlo
+        particle numbers.
+
     Parameters
     ----------
     value : str, int, or ParticleType

diff --git a/openmc/plots.py b/openmc/plots.py
@@ -357,7 +357,7 @@ def voxel_to_vtk(voxel_file: PathLike, output: PathLike = 'plot.vti'):
     return output
 
 
-def id_map_to_rgb(
+def _id_map_to_rgb(
     id_map: np.ndarray,
     color_by: str = 'cell',
     colors: dict | None = None,
@@ -716,7 +716,7 @@ class SlicePlot(PlotBase):
     (255, 255, 255) would be white, or by a string indicating a
     valid `SVG color <https://www.w3.org/TR/SVG11/types.html#ColorKeywords>`_.
 
-    .. versionadded:: 0.15.4
+    .. versionadded:: 0.16.0
 
     Parameters
     ----------
@@ -1140,7 +1140,7 @@ class VoxelPlot(PlotBase):
     (255, 255, 255) would be white, or by a string indicating a
     valid `SVG color <https://www.w3.org/TR/SVG11/types.html#ColorKeywords>`_.
 
-    .. versionadded:: 0.15.1
+    .. versionadded:: 0.16.0
 
     Parameters
     ----------
@@ -1382,7 +1382,7 @@ def to_vtk(self, output: PathLike | None = None,
 def Plot(plot_id=None, name=''):
     """Legacy Plot class for backward compatibility.
 
-    .. deprecated:: 0.15.4
+    .. deprecated:: 0.16.0
         Use :class:`SlicePlot` for 2D slice plots or :class:`VoxelPlot` for 3D voxel plots.
 
     """

diff --git a/openmc/settings.py b/openmc/settings.py
@@ -268,7 +268,7 @@ class Settings:
         enabled automatically for fixed-source simulations with weight
         windows active, and disabled otherwise.
 
-        .. versionadded:: 0.15.4
+        .. versionadded:: 0.16.0
     source : Iterable of openmc.SourceBase
         Distribution of source sites in space, angle, and energy
     source_rejection_fraction : float

diff --git a/openmc/source.py b/openmc/source.py
@@ -921,7 +921,7 @@ class TokamakSource(SourceBase):
     :math:`\Delta` is the Shafranov shift, and :math:`Z_\mathrm{shift}` is
     the vertical shift.
 
-    .. versionadded:: 0.15.4
+    .. versionadded:: 0.16.0
 
     Parameters
     ----------

diff --git a/openmc/stats/multivariate.py b/openmc/stats/multivariate.py
@@ -1281,7 +1281,7 @@ def cylindrical_uniform(
     a flat ring (annulus) at z=0 in the local coordinate frame. Optionally, the
     range of angles can be restricted by the `phis` argument.
 
-    .. versionadded:: 0.15.4
+    .. versionadded:: 0.16.0
 
     Parameters
     ----------
-Original file line number
+Diff line change
@@ Expand Up / @@ -7,6 +7,7 @@ Release Notes @@
     .. toctree::
       :maxdepth: 1
+.16.0
 .15.3
 .15.2
 .15.1
@@ Expand Down @@