Liquid lithium to molten salt heat exchanger with tritium extraction
UK
Several fusion power concepts propose the use of liquid lithium as the primary coolant and tritium breeder. Conventional heat exchangers (HEX) use water. To avoid tritium permeation into the water, a molten salt can be used as a secondary coolant, with water as the tertiary system.
This project developed a pre-conceptual design and feasibility analysis of a liquid metal to molten salt heat exchanger. The resulting HEX consists of a compact, counter-flow, plate-type unit. It also incorporates a novel concept of a leak detection system to prevent the liquid metal from coming into contact with the molten salt in the event of equipment failure.
This system uses an original concept consisting of a multi-layer arrangement of different materials in the plates and is based on the loss of electrical insulation between the ionised liquid and an electrically conductive layer. In addition, since the presence of tritium in the lithium can be a potential problem if it reaches the salt, the electrical insulating layer is also used as a tritium permeation barrier (TB), included in the design as a safety component.
The thermal, electrical, structural and manufacturability analyses demonstrate the feasibility of the proposed design and suggest that the use of a plate-type HEX is a feasible solution for fusion power concepts using liquid lithium as the primary coolant.
