Maximizing Temperatures of Delivered Heat from the Advanced High-Temperature Reactor

A new high-temperature reactor concept is being developed for hydrogen (H2) and electricity production: the Advanced High-Temperature Reactor (AHTR). The goal is to develop a large economic reactor with passive safety systems that delivers high-temperature heat with the coolant exit temperature as high as 1000EC. The high temperatures enable the production of H 2 using heat and water by efficient thermochemical cycles. The safety is to be equivalent to that of a modular high-temperature gas-cooled reactor (MHTGR). The AHTR fuel is a graphite-matrix coated-particle fuel, the type used in MHTGRs. The coolant is a molten fluoride salt with a boiling point near 1400EC. Because of this low-pressure liquid coolant, the types of passive safety systems proposed for liquid-metal reactors (such as the General Electric S-PRISM) can be used. The use of a low- pressure liquid coolant, rather than high-pressure helium, may reduce the materials and engineering challenges for very high-temperature reactors. Electricity is produced using a multi-reheat helium or nitrogen Brayton cycle. A preliminary preconceptual design of a 2400 MW(t) reactor has been developed with an output of 1300 MW(e) or an equivalent amount of H2.