Depletion with temperature interpolation causes segfault

[paulromano]

This issue was originally identified by a user. When running a depletion calculation with temperature interpolation turned on, OpenMC may end up segfaulting. The root cause of the issue is as follows:

• At initialization, when the temperature mode is set to interpolation, OpenMC will scan through materials to see what temperatures are present for each nuclide and load the corresponding datasets for temperatures that bound the temperatures that are present
• Nuclides that appear in the fuel but not in the moderator (e.g., U235) have cross sections loaded corresponding to the temperature of the fuel.
• For depletion, all nuclides that are present in the depletion chain are added to every depletable material if they are not already present (at a very low concentration). So, this results in nuclides like U235 getting added to the moderator because it is marked at depletable.
• However, those nuclides don’t have data loaded at the temperature of the moderator, which is what eventually causes the segfault (a temperature index goes out of bounds on an array)