b'P ROVING THE P RINCIPLEmillion project was the largest con- physics program continued its explo- $1 million worth of new space had beenstruction project in the history of Idaho, ration of neutron interactions with mat- built in 1962, and more was on the way.eclipsing the Mountain Home Air Base, ter. The work most immediately served The sponsors of MTR and ETR reactorwhich had cost over $30 million. With reactor designers, but also moved 20th experiments had to design the experi-a capability of operating at 250 century physics along in its progress ments, but they needed NRTS welders,megawatts, the ATR would be the toward understanding the atomic nucle- pipe fitters, carpenters, mechanics,largest test reactor in the world. If pro- us and ever smaller particles of matter. 12 heavy equipment operators, and otherjections held, it would begin operating specialists to build them. New and larg erev rin 1965. 9 The NRTS had long ago burst the seams craft shops were popping up. When e of its Naval Proving Ground inheritance a project or program vacated a building,The MTR was still working, having at Central Facilities. The growing safety someone else usually was waiting in thesurpassed 11,500 experiments. At the and materials testing programs needed wings, seeking relief from crowded con-Second Geneva Conference on the support labs and office space. Aboutditions elsewhere. 13 Peaceful Uses of Atomic Energy in1958, Phillips announced that the MTRhad run on plutonium-239 fuel at apower level of thirty megawatts forseveral months, adding more luster toits reputation. As the first water-moder-ated reactor to do this, the reactor con-firmed that plutonium could be areliable and controllable fuel for powerreactors. It was another first-in-the-world for the MTR. 10The ETR had been in service since1957. The ETRs on-stream time waslower than the MTRs, mainly becausethe elaborate experiments took moretime to set up. Competition for its ser-vice was heavy, especially with thespace program considering nuclearapplications. 11Other TRA facilities were equally busy.The early zero-power reactors hadgiven way to more advanced models.The Gamma Facility had irradiated itsfirst 100,000 samples and wasapproaching 200,000. The neutronPhoto and schematic of ATR showing basementsbelow operating floor.INEEL 68-4967162'