cyclus/cyclus — pull request #721 by scopatz (2014-02-19 15:42:22+00:00)
Title: ZZAAA form to PyNE's ID form (ZZZAAASSSS)

This adds the ability to represent metastable nuclides by adopting PyNE's nuclide ID format. This also closes a potential ambiguity where elements (92000) were allowed to be members of compositions - with the exception of hydrogen which had to be a nuclide (1001). Now only actual nuclides are allowed.

We should consider allowing users to specify nuclide string names instead of ids in the XML input file.

This closes #613