Event Timeslots (1)

Day 1 – June 20
-
Corrosion of metals by molten salts is a long-standing challenge in the nuclear industry for molten salt Generation IV reactor designs. Molten salts strip the oxide layers from metal alloys, exposing a bare metal surface to the salts that contain oxidising species, the unprotected metal surfaces corrode and leach alloying elements into the salts. At Moltex Energy for the SSR-U, corrosion is prevented by stabilisation of the redox potential. The SSR-U is a fluoride salt reactor with separate fuel and coolant salts. The reactor core comprises an array of fuel tubes that are maintained at a low pressure in a graphite matrix, which fills most of the tank. Each tube sits in a separate channel, within which a molten salt primary coolant circulates.

In the low enriched uranium fuel salt, control of the redox potential is achieved by controlling the oxidation states of the uranium salts which act as a redox buffer in a eutectic salt mixture with a sodium fluoride diluent. The redox buffer enables maintenance of redox potential and neutralisation of potentially corrosive fission products generated throughout the reactor’s lifespan. In the primary and secondary coolant salts, the redox potential is controlled by the addition of a proprietary redox control agent that scavenges any oxygen that leaks into the reactor before it can attack the metal.