 These reactors included initial experiments and test reactors that were the progenitors of today's pressurized water reactors (including naval reactors), boiling water reactors, heavy water reactors, graphite-moderated reactors, and liquid-metal cooled fast reactors, one of which was the first reactor in the world to generate electricity.Argonne and a number of other AEC contractors built a total of 52 reactors at the National Reactor Testing Station.Two were never operated; except for the Neutron Radiography Facility, all the other reactors were shut down by 2000.