Development Testing of Liquid Metal and Molten Salt Heat Exchangers

In order to investigate the design and fabrication problems inherent in compact, high-performance heat exchangers for aircraft nuclear propulsion applications, extensive development testing was done by the ANP Division of the Oak Ridge National Laboratory on bifluid (molten salt-NaK) heat exchangers and on liquid metal (NaK-air) radiators. These test units were prototypes of the heat transfer equipment which was to be used in the Aircraft Reactor Test at ORNL. Five bifluid test loops and one liquid metal test loop were used for performance and endurance testing of these components at simulated reactor operating conditions. The molten salt used was a sodium-zirconium-uranium fluoride mixture of composition NaF—50 mole %, ZrF₄—46 mole %, UF₄—4 mole %. The NaK used was 56 wt % sodium and 44 wt % potassium. A total of 47,000 hr of operation at 1200–1700°F was accumulated on 18 heat exchangers and 20 radiators. The program demonstrated that the compact heat exchanger geometries tested possessed the performance capabilities and mechanical integrity to meet ART design requirements.