We encountered an error where, upon restart, an interface that was expecting to use the core library was unable to use the core library because it could not be found. There are some application specific problems that led to this error.

In this specific case, an interface was operating in a temporary directory and invoked core.lib. The property will attempt to load from files in the current directory that match the cycle/node pair. However, none of the ISOTXS-* files exist in this temporary directory, so no library was loaded. This caused the application to crash b/c it didn't have the core library.

But it got me thinking. When we do a restart calculation, should ARMI attempt to reload the cross section library for the restart point?

The main interface handles loading the database and setting the reactor state up. It could attempt to load the core cross section library for the requested time node. Then, all the interfaces have the same runtime data they expect to have.

You would probably want to load the cross section library from the previous time point so that, when you restart, you reflect the xs library you had at runtime.