Another nuclear reactor designed and operated by the US Air Force. This was part of an experiment to produce a nuclear powered airplane. The control rods were withdrawn automatically instead of manually. Part of the electronic control system failed and thought the reactor was 'off' instead of powered up, so it continued to withdraw the control rods until the reactor became so hot it melted down, shooting radioactive debris out the back of the engine of the plane. This is why the Air Force doesn't have any more nuclear reactors.