The Bulk Shielding Reactor and Tower Shielding Facility were designed to test materials that might be used on a nuclear-powered aircraft. For the U.S. Air Force, improved materials represented a means toward an end: a nuclear-powered engine that could drive long-range bombers to takeoff speeds and propel them around the world. To achieve this goal, the Laboratory designed an experimental 100-kW aircraft reactor as a demonstration.
Mock-up of ORNL's "Fireball" reactor designed for sophisticated experiments.
This small reactor, operating at high temperatures, used molten uranium salts as its fuel, which flowed in serpentine tubes through an 18-inch (46-centimeter) reactor core. A heat exchanger dissipated the reactor's heat into the atmosphere. In 1953, the Laboratory constructed a building to house this experimental reactor.
To contain molten salts at high temperatures within a reactor, the Laboratory used a nickel-molybdenum alloy, INOR-8, designed by Oak Ridge researchers and fabricated at the International Nickel Company. Able to resist corrosion at high temperatures while retaining acceptable welding properties, the alloy was commercialized as Hastelloy-N by private industry (an early example of technology transfer) to supply tubing, sheet, and bar stock for industrial applications. The aircraft reactor also compelled Laboratory personnel to learn how to perform welding with remote manipulators and how to remotely disassemble molten-salt pumps. In addition, Laboratory researchers also devised two salt reprocessing schemes to recover uranium and lithium-7 from spent reactor fuel.
The first test run of the Aircraft Reactor Experiment took place in October 1954. The reactor ran at 1 MW for 100 hours. Don Trauger and other observers of the reactor's operations recall that the reactor core, pumps, valves, and components literally became red hot. Completing the design, fabrication, and operation of such an exotic nuclear reactor in five years was considered a noteworthy event, and dignitaries such as General James Doolittle, Admiral Lewis Strauss, and Captain Hyman Rickover visited Oak Ridge to see the red-hot reactor in action.
