50 YEARS OF OPERATION It is an honor to be the associate laboratory director for the 50th anniversary of the Advanced Test Reactor’s first day of operation. There have been many research, test and power reactors in the world, but there is only one ATR. We, the men and women who have worked here, both now and in the past, are very proud to operate, support and maintain this amazing, one-of-a-kind nuclear facility. Over the past five decades of operation, ATR has supported irradiation research programs in nuclear power and propulsion, and we expect to continue to operate ATR many decades into the future, so we may sustain these programs that are vital to our country. Our reactor is supporting more nuclear materials research and development now than at any time in its history. There are more experiments, and more complicated experiments, to perform, which keep us busy preparing experimental safety and core design packages for the next operating cycle. At the same time, the other half of ATR is preparing engineering designs and performing maintenance activities to systematically refurbish or replace equipment that will allow ATR to deliver its mission safely and reliably for years to come. –Dr. Sean O’Kelly, ATR Associate Laboratory Director