The tritium extraction and removal system for the DCLL-DEMO fusion reactor

During the pre-conceptual design phase of DEMO, different alternatives have been explored to be implemented as tritium extraction and removal system (TERS) for the blanket concepts considered in EUROfusion. The TERS is conceived to extract tritium from the breeder and to route it to the Tritium Plant for final processing. A careful review showed that those blankets operated with PbLi should use the permeation against vacuum (PAV) technique as primary option which is based on a one-step, fully continuous procedure. In this paper, a conceptual design of the TERS for the dual coolant lithium lead (DCLL) breeding blanket is presented, based on the European DEMO2015 layout (18 sectors, 2037 MW fusion power). The P&ID of the proposed TERS, integrated in the DCLL-PbLi loop, includes valves and instrumentation, as well as a revised design of the DCLL-PAV. The dimensioning of the permeator considered a tritium extraction efficiency of 80%. An exhaustive investigation on the vacuum system needed for the PAV is also presented. The choice of the most promising vacuum systems took into account the reliability and tritium compatibility of both high and rough pumps. Their pumping requirements, which are dependent on the PAV efficiency, tritium solubility and tritium partial pressure in the loop, are also discussed in this work.