Add PNNL 15870 to openmc.model

Development
#1

The document in the title is here.

It contains a huge list of standard material compositions for radiation transport calculations. This would fit nicely into openmc.model.

#2

Note that PyNE includes this data in their material library. It might already be possible to get a corresponding OpenMC material since their Material class has a openmc() method that produces XML (which we could parse with openmc.Material.from_xml_element?).

Obviously being able to get this from openmc.model would be way simpler for a user.

#3

Ah, good idea. Maybe we could just get the XML from PyNE, and include it in openmc.model?

#4

This minimal neutronics material package also includes PNNL materials

It also includes additional materials that have densities that vary with pressure / temperature / density / enrichment

Materials like Helium gas, FLiBe, Li4SiO4 can therefore be accommodated and the database has density equations for these materials and others. This allows the to vary their density with temperature and density automatically.

#5

Just to follow up this topic, I’ve put in a pull request to add PNNL revision 2 materials.