Design of a Helium-Cooled Molten-Salt Fusion Breeder

A new conceptual blanket design for a fusion reactor produces fissile material for fission power plants. Fission is suppressed by using beryllium, rather than uranium, to multiply neutrons and also by minimizing the fissile inventory. The molten-salt breeding media (LiF+BeF₂+ThF₄) is circulated through the blanket and on to the online processing system where ²³³U and tritium are continuously removed. Helium cools the blanket including the steel pipes containing the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion rate by molten salt. We estimate the breeder, having 3000 MW of fusion power, produces 6400 kg of ²³³U per year, which is enough to provide make up for 20 GWe of LWR per year (or 14 LWR plants of 4440 MW_t) or twice that many HTGRs or CANDUs. Safety is enhanced because the afterheat is low and the blanket materials do not react with air or water. The fusion breeder based on a pre-MARS tandem mirror is estimated to cost $4.9B or 2.35 times an LWR of the same power. The estimated present value cost of the ²³³U produced is $40/g if utility financed or $16/g if government financed.