From e7a9a1e23617d593c504feba7ea8cf6c7b5a323e Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Tue, 7 Jun 2016 09:17:21 -0500
Subject: [PATCH] When expanding natural elements, make sure order is
 consistent

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

diff --git a/openmc/element.py b/openmc/element.py
index c391d08235..14c98d4952 100644
--- a/openmc/element.py
+++ b/openmc/element.py
@@ -126,7 +126,7 @@ class Element(object):
         """
 
         isotopes = []
-        for isotope, abundance in natural_abundance.items():
+        for isotope, abundance in sorted(natural_abundance.items()):
             if isotope.startswith(self.name + '-'):
                 nuc = openmc.Nuclide(isotope, self.xs)
                 isotopes.append((nuc, abundance))