50 YEARS OF OPERATION 3 4 1.  Construction of ATR facilities. Jan. 4, 1962. 2.  Construction of ATR facilities, looking northeast at excavation operations for reactor building foundations. Dragline at left is mucking out rock from heat exchanger pit. Backhoe is stripping overburden in rod access and waste pit area. 3.  Reactor vessel and core internals assembly being transported by truck from Central Facilities Area to ATR Complex after arriving by rail. 4.  ATR predecessor, the Materials Test Reactor (MTR), was the first reactor at the ATR Complex. A view of the MTR core and reflector. 5.  ATR reactor vessel and core internals assembly ready to be lowered into position. 5