From 2d8e006c3de9c8fbc0b010357ebf5a870909c8bc Mon Sep 17 00:00:00 2001
From: Perry <100789850+yrrepy@users.noreply.github.com>
Date: Mon, 3 Nov 2025 09:10:30 -0800
Subject: [PATCH] Enable nuclide filters with get_decay_photon_energy (#3614)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>
---
 openmc/material.py | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/openmc/material.py b/openmc/material.py
index c7b954b66..1609da05a 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -290,11 +290,13 @@ class Material(IDManagerMixin):
         return self.get_decay_photon_energy(0.0)
 
     def get_decay_photon_energy(
-            self,
-            clip_tolerance: float = 1e-6,
-            units: str = 'Bq',
-            volume: float | None = None
-        ) -> Univariate | None:
+        self,
+        clip_tolerance: float = 1e-6,
+        units: str = 'Bq',
+        volume: float | None = None,
+        exclude_nuclides: list[str] | None = None,
+        include_nuclides: list[str] | None = None
+    ) -> Univariate | None:
         r"""Return energy distribution of decay photons from unstable nuclides.
 
         .. versionadded:: 0.14.0
@@ -302,22 +304,31 @@ class Material(IDManagerMixin):
         Parameters
         ----------
         clip_tolerance : float
-            Maximum fraction of :math:`\sum_i x_i p_i` for discrete
-            distributions that will be discarded.
+            Maximum fraction of :math:`\sum_i x_i p_i` for discrete distributions
+            that will be discarded.
         units : {'Bq', 'Bq/g', 'Bq/kg', 'Bq/cm3'}
             Specifies the units on the integral of the distribution.
         volume : float, optional
             Volume of the material. If not passed, defaults to using the
             :attr:`Material.volume` attribute.
+        exclude_nuclides : list of str, optional
+            Nuclides to exclude from the photon source calculation.
+        include_nuclides : list of str, optional
+            Nuclides to include in the photon source calculation. If specified,
+            only these nuclides are used.
 
         Returns
         -------
         Univariate or None
-            Decay photon energy distribution. The integral of this distribution
-            is the total intensity of the photon source in the requested units.
+            Decay photon energy distribution. The integral of this distribution is
+            the total intensity of the photon source in the requested units.
 
         """
         cv.check_value('units', units, {'Bq', 'Bq/g', 'Bq/kg', 'Bq/cm3'})
+
+        if exclude_nuclides is not None and include_nuclides is not None:
+            raise ValueError("Cannot specify both exclude_nuclides and include_nuclides")
+
         if units == 'Bq':
             multiplier = volume if volume is not None else self.volume
             if multiplier is None:
@@ -332,6 +343,11 @@ class Material(IDManagerMixin):
         dists = []
         probs = []
         for nuc, atoms_per_bcm in self.get_nuclide_atom_densities().items():
+            if exclude_nuclides is not None and nuc in exclude_nuclides:
+                continue
+            if include_nuclides is not None and nuc not in include_nuclides:
+                continue
+
             source_per_atom = openmc.data.decay_photon_energy(nuc)
             if source_per_atom is not None and atoms_per_bcm > 0.0:
                 dists.append(source_per_atom)