From e360cb467e9b97412c4fcbfbc58c0ff4226b5014 Mon Sep 17 00:00:00 2001
From: Jonathan Shimwell <mail@jshimwell.com>
Date: Thu, 6 Mar 2025 17:39:05 +0100
Subject: [PATCH] added stable and unstable nuclides to the Chain object
 (#3338)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>
---
 openmc/deplete/chain.py                | 20 ++++++++++++++++++--
 tests/unit_tests/test_deplete_chain.py |  8 ++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/openmc/deplete/chain.py b/openmc/deplete/chain.py
index 2e81250dcf..4998a2c3d9 100644
--- a/openmc/deplete/chain.py
+++ b/openmc/deplete/chain.py
@@ -12,6 +12,7 @@ from collections import defaultdict, namedtuple
 from collections.abc import Mapping, Iterable
 from numbers import Real, Integral
 from warnings import warn
+from typing import List
 
 import lxml.etree as ET
 import scipy.sparse as sp
@@ -244,6 +245,10 @@ class Chain:
         Reactions that are tracked in the depletion chain
     nuclide_dict : dict of str to int
         Maps a nuclide name to an index in nuclides.
+    stable_nuclides : list of openmc.deplete.Nuclide
+        List of stable nuclides available in the chain.
+    unstable_nuclides : list of openmc.deplete.Nuclide
+        List of unstable nuclides available in the chain.
     fission_yields : None or iterable of dict
         List of effective fission yields for materials. Each dictionary
         should be of the form ``{parent: {product: yield}}`` with
@@ -256,7 +261,7 @@ class Chain:
     """
 
     def __init__(self):
-        self.nuclides = []
+        self.nuclides: List[Nuclide] = []
         self.reactions = []
         self.nuclide_dict = {}
         self._fission_yields = None
@@ -272,7 +277,18 @@ class Chain:
         """Number of nuclides in chain."""
         return len(self.nuclides)
 
-    def add_nuclide(self, nuclide):
+
+    @property
+    def stable_nuclides(self) -> List[Nuclide]:
+        """List of stable nuclides available in the chain"""
+        return [nuc for nuc in self.nuclides if nuc.half_life is None]
+
+    @property
+    def unstable_nuclides(self) -> List[Nuclide]:
+        """List of unstable nuclides available in the chain"""
+        return [nuc for nuc in self.nuclides if nuc.half_life is not None]
+
+    def add_nuclide(self, nuclide: Nuclide):
         """Add a nuclide to the depletion chain
 
         Parameters
diff --git a/tests/unit_tests/test_deplete_chain.py b/tests/unit_tests/test_deplete_chain.py
index 9753a53f73..13267cb051 100644
--- a/tests/unit_tests/test_deplete_chain.py
+++ b/tests/unit_tests/test_deplete_chain.py
@@ -86,6 +86,14 @@ def test_from_endf(endf_chain):
         assert nuc == chain[nuc.name]
 
 
+def test_unstable_nuclides(simple_chain: Chain):
+    assert [nuc.name for nuc in simple_chain.unstable_nuclides] == ["A", "B"]
+
+
+def test_stable_nuclides(simple_chain: Chain):
+    assert [nuc.name for nuc in simple_chain.stable_nuclides] == ["H1", "C"]
+
+
 def test_from_xml(simple_chain):
     """Read chain_test.xml and ensure all values are correct."""
     # Unfortunately, this routine touches a lot of the code, but most of