Effects of Radiative Heat Transfer in High-Temperature Liquid-Salts
Recent technological advances and needs for high-temperature heat have increased interest in nuclear power systems that utilize liquid-salts such as Fluoride-salt-cooled High-temperature Reactors (FHR), Molten Salt Reactors (MSR), and high-magnetic-field fusion machines with immersion salt coolant blankets. These systems can be used to provide high-temperature heat to high carbon-emitting industrial processes such as oil refining, hydrogen production, and shale oil recovery. Additionally, improved gas turbine technology has made coupling high-temperature reactors to Nuclear Air-Brayton Combined Cycles possible. This allows for both base-load and peak electricity production that can increase system efficiency and net revenue. New fusion reactor designs with increased power density and smaller sizes can also benefit from liquid salt blankets to produce tritium while providing neutron and gamma shielding to high-field magnets. These applications when combined with enhancements in safety, fuel cycle, and cost make liquid-salt reactors an attractive option for new nuclear power systems. However, despite successful experiments such as the Molten Salt Reactor Experiment, the limited experience with liquid-salt coolants leaves unanswered questions. Understanding of the thermal hydraulic and heat transfer performance of these salts needs to be improved, especially in the area of radiative heat transfer. Liquid salt systems have typical operating temperatures between 600 and 700 deg. C. Because thermal radiation scales approximately as T4, its effects begin to become important in this temperature range. Under higher-temperature off-normal conditions radiative heat transfer can become a major mechanism of heat transfer.