From 7900ad925afd4932aaf19ce7cddd4d9e6e4e9642 Mon Sep 17 00:00:00 2001
From: Will Boyd <wbinventor@gmail.com>
Date: Fri, 20 Jan 2017 13:21:06 -0500
Subject: [PATCH] Updated regex to cross reference nuclides with elements

---
 openmc/data/data.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/openmc/data/data.py b/openmc/data/data.py
index 728b5b96ff..9759411abd 100644
--- a/openmc/data/data.py
+++ b/openmc/data/data.py
@@ -200,7 +200,7 @@ def atomic_weight(element):
     """
     weight = 0.
     for nuclide, abundance in NATURAL_ABUNDANCE.items():
-        if re.match(element, nuclide):
+        if re.match(r'{}\d+'.format(element), nuclide):
             weight += atomic_mass(nuclide) * abundance
     return None if weight == 0. else weight