Fuel source isotopic tailoring and its impact on international thermonuclear experimental reactor design, operation, and safety

Isotopic tailoring of the deuterium and tritium density profiles in fusion reactors can lead to reduced tritium inventory in plasma facing components and, therefore, improved safety considerations. The isotopic tailoring concept consists of utilizing a tritium-rich pellet source for core fueling and a deuterium-rich gas source for edge fueling. Because of the improved particle confinement associated with the deeper tritium core fueling component, comparable core densities of deuterium and tritium can be maintained even when the edge deuterium fuel source is much larger than the core tritium fuel source. The fuel composition of the edge and scrape-off plasmas as well as the isotope fractions in plasma facing components reflect the total throughput of all makeup fuel and are therefore deuterium-rich. This innovative fueling concept results in about a factor of two reduction in tritium inventory of the plasma facing components. The higher tritium burn fraction allows a significant reduction in tritium gas flows into and out of the vacuum vessel and, for fusion reactors, implies lower required tritium breeding ratios.