purpose than just generating electricity, however, was its role in proving that a reactor could create more nuclear fuel as a by-product than it consumed during operation. In 1953, tests verified that this was the case. The site of this event is memorialized as a Registered National Historic Landmark, open to the public every day Memorial Day through Labor Day. Experimental Breeder Reactor II (EBR-II) From 1969 to 1994, Argonne National Laboratory's EBR-II produced nearly half of the electricity needed for test site operations. In 1964, Experimental Breeder Reactor II and the nearby Fuel Conditioning Facility proved the concept of fuel recycling and passive safety characteristics. So-called "passive" safety includes systems that rely on natural physics laws such as gravity rather than systems that require mechanical or human intervention. In a landmark test on April 3, 1986, such systems in EBR-II demonstrated that nuclear power plants could be designed to be inherently safe from severe accidents. De-commissioning of EBR-II began in October 1994 with the removal of the 637 fuel assemblies. Loss of Fluid Test (LOFT) facility The world's first Loss-of-Fluid-Test reactor started up at INL on March 12, 1976. It repeatedly simulated loss-of-coolant accidents that could potentially occur in commercial nuclear power plants. Many safety designs for reactors around the world are based on these tests. LOFT experiments helped accident recovery efforts after the Three Mile Island accident in 1979. Test Area North In 1949, an area of the fringe of the NRTS property named "Test Area North", or TAN, was developed by the U.S. Air Force and the Atomic Energy Commission to support the Aircraft Nuclear Propulsion program's attempt to develop a nuclear-powered aircraft. The program's Heat Transfer Reactor Experiments (HTRE) were conducted here in 1955 by contractor General Electric, and were a series of tests to develop a system of transferring reactor-heated air to a modified General Electric J47 jet engine. The planned aircraft, the Convair X-6, was to be test flown at TAN, and a large hangar with radiation shielding was built on the site. The program was cancelled, however, before the accompanying runway could be built. Naval Reactors Facility (NRF) In the early 1950s, the very first full-scale prototype nuclear plant for shipboard use, called S1W Prototype, was constructed to test the feasibility of using nuclear power aboard submarines. It was the predecessor to a similar nuclear plant of S2W design installed in the first