Commissioning Scenario Without Initial Tritium Inventory for a Demonstration Reactor Demo-CREST

We discuss the applicability of the commissioning scenario without the initial tritium inventory to Demo-CREST. Analysis on MHD stability and current drive property (i.e., NBI injection power, its injection region, the driven current profile, etc.) makes clear the potential to start up the plasma operation without the initial tritium inventory. The critical issue on the core plasma operation is the high confinement of HH=1.57. We also discuss the tritium dead inventory in the plasma area. The key for the commissioning period without the initial tritium inventory is found to be the increment of the dead inventory. Finally, the required commissioning period is estimated at 75~110 days for the net TBR_DT=1.05. That possibility strongly depends on the increment of the dead inventory, and understanding the tritium behavior not only in the plasma region but also in other tritium subsystem is important.