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Friday, June 14

Fluoride-Salt-Cooled High-Temperature Reactors:
Enabling a Low-Carbon Nuclear-Renewable Electricity Grid

Charles W. Forsberg, Massachusetts Institute of Technology, Cambridge
Reactor and Nuclear Systems Division Seminar
10:00 AM — 11:00 AM, Building 4500-N, Weinberg Auditorium
Contact: Graydon L. Yoder, Jr. (, 865.574.5282


The Fluoride-Salt-Cooled High-Temperature Reactor (FHR) is a new reactor concept being developed to (1) enable a low-carbon nuclear renewable electricity grid and (2) increase plant revenues by 50% relative to base-load nuclear power plants. The FHR uses graphite-matrix coated-particle fuel developed originally for gas-cooled reactors and a clean liquid fluoride salt coolant originally developed for molten salt reactors. This combination allows delivery of heat between 600°C and 700°C to a Nuclear Air-Brayton Combined Cycle (NACC) power system with power peaking capabilities using auxiliary natural gas, biofuels, or hydrogen.

In an NACC power cycle, air is compressed and heated with nuclear heat, goes through a power turbine, and is exhausted to a heat-recovery steam generator, where the steam produces added electricity. Only a salt-cooled reactor can couple to NACC because modern jet engine compressors heat air to between 450°C and 550°C—requiring that the reactor deliver all heat above these temperatures. NACC can produce peak power by injecting natural gas after nuclear heating and further raising the peak gas turbine temperature. Because the peaking power is added to an existing base-load power plant, the response time to changes in grid demand is very fast. The efficiency of natural gas to electricity is greater than stand-alone natural gas plants. These characteristics increase plant revenue while matching the needs of a low-carbon nuclear-renewable electricity grid.