fix #7257 Source "From File" now uses openmc.FileSource() class (#7437)

Author: moellep

sirepo/package_data/static/js/openmc.js

@@ -2644,7 +2644,7 @@ SIREPO.app.directive('sourcesOrTalliesEditor', function(appState, panelState) {
             $scope.description = m => {
                 if (childModel === 'source')  {
                     return m.type === 'file' && m.file
-                         ? `File(filename=${m.file })`
+                         ? `FileSource(${m.file })`
                          : sourceInfo('SpatialDistribution', m.space);
                 }
                 return tallyInfo(m);

sirepo/template/openmc.py

@@ -9,7 +9,6 @@
 from pykern.pkcollections import PKDict
 from pykern.pkdebug import pkdc, pkdp, pkdlog, pkdexc
 from sirepo import simulation_db
-from sirepo import util
 from sirepo.template import template_common
 import CAD_to_OpenMC.assembly
 import gzip
@@ -785,7 +784,7 @@ def _generate_save_weight_windows(data):
 
 def _generate_source(source, qcall):
     if source.get("type") == "file" and source.get("file"):
-        return f"openmc.IndependentSource(filename=\"{_SIM_DATA.lib_file_name_with_model_field('source', 'file', source.file)}\")"
+        return f"openmc.FileSource(\"{_SIM_DATA.lib_file_name_with_model_field('source', 'file', source.file)}\")"
     if source.space._type == "box":
         # TODO(pjm): move only_fissionable outside of box
         c = f"{{'fissionable': {source.space.only_fissionable == '1'}}}"