3. Fuel Flow and Balance in a D–T Fusion Reactor

Because of radioactivity of tritium (T), special cares for safety are required. In addition, limited resources of T require fuel self-sufficiency in a fusion reactor. Accordingly, accurate T accountancy, i.e., to know quantitatively how much T is in throughput, exhausted, and retained in all T handling systems in a reactor is required. At the same time, T retention in any systems should be minimized, or T retained in the systems should be recovered as much as possible. In this chapter, fuel flows and balances in all fuel processing/handling subsystems of a reactor are introduced referring deuterium (D) flow in present experimental tokamaks, which are using D as operating gas. Subsequently, current designs of the fueling and recycling systems of a fusion reactor are introduced and required conditions to keep T safety and fuel self-sufficiency are considered.