Not compatible with ``explicit_inventory`` option

[abachma2]

When the explicit_inventory tag of the control block of the cyclus input file is marked true, then DepleteReactor does not operate correctly.

Observed behavior:

• After accepting assemblies, the core count matches what is expected. This continues until the time step that fuel should be transmuted
• In the tick phase of the time step that fuel is transmuted (fuel is transmuted during the tick phase) the core count goes to 0
• Because there are 0 assemblies in the core, fuel is not transmuted and the prototype continues to accept more fuel assemblies (a core-worth of assemblies) at every subsequent time step.

Expected behavior:

• After accepting assemblies, the core count matches what is expected. This continues until the time step that fuel should be transmuted
• In the tick phase of the time step that fuel is transmuted, the core is still full
• Fuel is transmuted with the specified parameters at the end of the operating cycle
• More fuel is requested and accepted at the correct intervals (i.e., after an operating cycle).

It is very possible that this issue is because of something in the Cyclus python API, and not specific to this software.