From 1b177634f4c805f238da4f809ef1a18d2b060666 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Tue, 31 Mar 2020 17:41:12 -0500
Subject: [PATCH] Changes in data/decay.py from PullRequest Inc. review

---
 openmc/data/decay.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/openmc/data/decay.py b/openmc/data/decay.py
index 6a8ad39f09..9134b48291 100644
--- a/openmc/data/decay.py
+++ b/openmc/data/decay.py
@@ -142,12 +142,12 @@ class FissionProductYields(EqualityMixin):
             'isomeric_state': ev.target['isomeric_state']
         }
 
-        # Read independent yields
+        # Read independent yields (MF=8, MT=454)
         if (8, 454) in ev.section:
             file_obj = StringIO(ev.section[8, 454])
             self.energies, self.independent = get_yields(file_obj)
 
-        # Read cumulative yields
+        # Read cumulative yields (MF=8, MT=459)
         if (8, 459) in ev.section:
             file_obj = StringIO(ev.section[8, 459])
             energies, self.cumulative = get_yields(file_obj)
@@ -372,6 +372,7 @@ class Decay(EqualityMixin):
 
             items, values = get_list_record(file_obj)
             spin = items[0]
+            # ENDF-102 specifies that unknown spin should be reported as -77.777
             if spin == -77.777:
                 self.nuclide['spin'] = None
             else: