System design and description of a molten salt loop

Abstract

Molten salt reactors (MSRs) use molten salts (instead of water or other fluids) to remove nuclear fission power from the reactor core. A molten salt loop system can be used to test materials and components for MSRs. In this thesis, the molten salt loop system design was described and analyzed. For an 8 feet by 3 feet molten salt loop with a 1.25 inch inner diameter pipe operating at 800°C, the required drain tank heater power needed to heat up the 11.6 kilograms of FLiNaK molten salt in 60 minutes was found to be approximately 12 kW. The power of the band heaters needed to maintain the operating temperature as the molten salt flows around the loop was calculated to be approximately 0.79 kW for pipes insulated with a 2 inch thick ceramic fiber insulation sheet. The pump used to circulate the molten salt through the piping was found to have a minimum required horsepower of 0.154 horsepower. The drive shaft needs to be approximately 1 meter long in order to dissipate the heat going from the 800°C molten salt to the ambient temperature pump motor. Commonly available components containing materials such as zinc, plastics, glues, or resins cannot be used in the molten salt loop design due to the extremely high operating temperature of the molten salt loop. Thermal expansion of the molten salt loop has to be taken into account when designing and constructing it. Extremely high operating temperatures and the corrosivity of the molten salt are some of the design challenges that need to be considered when designing molten salt loops in a laboratory.