CONVERGING FISSION AND FUSION SYSTEMS TOWARD HIGH-TEMPERATURE LIQUID-SALT COOLANTS: IMPLICATIONS FOR RESEARCH AND DEVELOPMENT STRATEGIES

摘要

Recent technology advances are creating growing interests in three nuclear technologies that require high-temperature salt coolants: (1) Fluoride-salt-cooled High-Temperature Reactors (FHRs) with solid fuel and liquid salt coolants, (2) Molten Salt Reactors (MSRs) with fuel dissolved in the salt coolant, and (3) high-magnetic-field fusion machines with immersion salt coolant blankets. The FHR is enabled by improved graphite-matrix coated-particle fuel developed for high-temperature gas-cooled reactors (HTGRs). Multiple technological advances primarily from outside nuclear engineering are improving MSR viability. A new superconductor that enables doubling magnetic fields in fusion machines may reduce fusion machine size by a factor or ten or more that, in turn, improves fusion viability and creates large incentives to use liquid salt immersion blankets for cooling, shielding and tritium production. Salt coolants were originally developed for the Aircraft Nuclear Propulsion Program in the 1950s with the goal of coupling a nuclear reactor to aircraft jet engines. They can transfer heat from the reactor to the power cycle at between 600 and 700°C. Recent advances in utility natural-gas combined-cycle technologies now enable coupling these reactors to a Nuclear Air-Brayton Combined Cycle (NACC) or potentially a Nuclear Helium Combined Cycle (NHCC). NACC can provide base-load electricity with additional variable peak electricity produced by using auxiliary natural gas, biofuels, hydrogen, or stored heat to (1) increase nuclear plant net revenue by 50 to 100% relative to base-load nuclear plants and (2) enable a low-carbon nuclear renewable electricity system. These developments create large incentives for cooperative research and development programs on salt coolants (corrosion, heat transfer, tritium control, etc.) and the associated power systems to advance and commercialize these three technologies.