Do not add radioactive Ta180 when calling add_element('Ta') (#3750)

Author: paulromano

openmc/element.py

@@ -184,8 +184,6 @@ def expand(self, percent, percent_type, enrichment=None,
                 for nuclide in absent_nuclides:
                     if nuclide in ['O17', 'O18'] and 'O16' in mutual_nuclides:
                         abundances['O16'] += NATURAL_ABUNDANCE[nuclide]
-                    elif nuclide == 'Ta180_m1' and 'Ta180' in library_nuclides:
-                            abundances['Ta180'] = NATURAL_ABUNDANCE[nuclide]
                     elif nuclide == 'Ta180_m1' and 'Ta181' in mutual_nuclides:
                             abundances['Ta181'] += NATURAL_ABUNDANCE[nuclide]
                     elif nuclide == 'W180' and 'W182' in mutual_nuclides:

tests/unit_tests/test_element.py

@@ -45,11 +45,11 @@ def test_expand_no_isotopes():
 
 
 def test_expand_ta():
-    ref = {'Ta180': 0.01201, 'Ta181': 99.98799}
+    ref = {'Ta181': 100.0}
     element = openmc.Element('Ta')
     for isotope in element.expand(100.0, 'ao'):
         assert isotope[1] == approx(ref[isotope[0]])
-    
+
 
 def test_expand_exceptions():
     """ Test that correct exceptions are raised for invalid input """