A fusion reactor design with a liquid first wall and divertor

Abstract

Within the magnetic fusion energy program in the US, a program called APEX is investigating the use of free flowing liquid surfaces to form the inner surface of the chamber around the plasma. As part of this work, the APEX Team has investigated several possible design implementations and developed a specific engineering concept for a fusion reactor with liquid walls. Our approach has been to utilize an already established design for a future fusion reactor, the ARIES-RS, for the basic chamber geometry and magnetic configuration and to replace the chamber technology in this design with liquid wall technology for a first wall and divertor and a blanket with adequate tritium breeding. This paper gives an overview of one design with a molten salt (a mixture of lithium, beryllium and sodium fluorides) forming the liquid surfaces and a ferritic steel for the structural material of the blanket. The design point is a reactor with 3840MW of fusion power of which 767MW is in the form of energetic particles (alpha power) and 3073MW is in the form of neutrons. The alpha plus auxiliary power total 909MW of which 430MW is radiated from the core mostly onto the first wall and the balance flows into the edge plasma and is distributed between the first wall and the divertor. In pursuing the application of liquid surfaces in APEX, the team has developed analytical tools that are significant achievements themselves and also pursued experiments on flowing liquids. This work is covered elsewhere, but the paper will also note several such areas to indicate the supporting science behind the design presented. Significant new work in modeling the plasma edge to understand the interaction of the plasma with the liquid walls is one example. Another is the incorporation of magneto-hydrodynamic (MHD) effects in fluid modeling and heat transfer.

Moving Divertor Plates in a Tokamak

“…4. Similar processes steps were described previously for the other moving divertor ideas [4][5][6][7][8][9].…”

“…It is not yet clear whether a moving plate system would be more or less feasible than other similar ideas for movable divertors, e.g. moving belts [4,5], pebble divertors [6,7], or liquid walls [8,9]. Perhaps the main advantage of the moving plate system is that the plasma facing surface will be more robust and more similar to conventional divertor plates than these other systems.…”

“…The pebble divertor [6,7] would perform similar functions, but with a gravity-driven stream of small pebbles falling through the divertor. The liquid wall divertor would perform the same functions with a moving liquid stream or gravity-driven droplets [8,9]. However, so far the only moving surfaces used in a tokamak were a rotating limiter tested on PLT [10] and a gallium droplet limiter tested on T-3M [8].…”

Rapidly Moving Divertor Plates in a Tokamak

“…4. Similar processes steps were described previously for the other moving divertor ideas [1][2][3][4][5][6][7] . Figure 4 -Plate processing outside the tokamak.…”

“…The liquid wall divertor would perform the same functions with a moving liquid stream or gravity-driven droplets [5][6][7] . However, so far the only moving surfaces used in a tokamak were a rotating limiter tested on PLT 8 and a gallium droplet limiter tested on T-3M 5 .…”