b'I reached over across the front seat of the car andwith\x07my\x07finger\x07drew\x07four\x07circles\x07for\x07test\x07loops,\x07and\x07then a snakelike fuel line partially around each loopThe more we looked at that strange arrangement, 1967 the better it looked.Deslonde deBoisblanc, on the inspiration\x07for\x07ATRs\x07core\x07configuration\x07striking\x07him\x07while driving home from the SiteAdvanced Test ReactorWhen the AEC and the Navy requested a new test reactor with less neutron flux variation, the result was ATR. It first reached criticality on July 2, 1967, and reached its full 250-megawatt power level in August 1969, becoming the largest test reactor in the world.The reactors distinctive cloverleaf design offers a wide range of power levels to nine maintest spaces or loops, each with its own distinct environment apart from that of the main reactor core. While its main customer was the U.S. Navy, ATR became the linchpin of a National Scientific User Facility in 2007, making it available to researchers across theU.S. and around the world. It completed its sixth core internals changeout in 2022 and remains in operation today.43'