b'P ROVING THE P RINCIPLEwhich meant having space in the reac- entist with no doctorate in physics buttor to run several tests at the same time who nonetheless had a feel for the wayand expose them to a very high flux of neutrons behave, created an elegantneutrons. ETR flux was too low and its design for the reactor core in 1959. Thetest loops were too small. 4 design, named Advanced Test Reactor(ATR), first of all solved the symmetryBesides that, the normal way of operat- problem. DeBoisblanc described theing the MTR and ETR created prob- ATRs new way of controlling thelems. Typically, control rods moved up power level.or down during operation to regulatethe power level of the reactor. But if a I tried to avoid a common problemtest sample several inches long was in encountered in most other test reactors,the reactor parallel to a control rod, the where the control elements move up orneutron exposure to the top and bottom down. In the ATR, the larger range ofhalves of the sample would not be the control is accomplished by rotating six -same for the duration of the test. In the teen beryllium cylinders with hafniumMTR the variation could amount to shells that cover 120 of the outer sur -INEEL Cultural Resources thirty percent; in the ETR, ten percent. face. (Hafnium is a strong neutronDeslonde deBoisblanc The Navy wanted to reduce the per- absorber.) The cylinders are situatedcentage even more. Its planned experi- around the core. When rotated singly orments required perfect symmetryor in groups, the hafnium moves closer orgenerations of the concepts they repre- as close to perfect as possiblealong farther from the core, thereby control -sented. In late 1963, construction crews the entire length of a test sample.ling reactivity without disturbing thewere back in force, the annual payroll vertical power profile.was high and growing, and new initia- In the late 1950s, the AEC and thetives were evident everywhere. Even Navy invited a number of companies to The design also included small neutron-space-age projects had arrived at the make proposals for an advanced test absorbing control rods. Unlike controlNRTS. Nationally, nuclear power plants reactor that would serve not only the rods in earlier reactors, these were notwere about to move into the commer- Navy but the AECs other test needs for moved slowly up or down during reac-cial market, and the demand for safety many years to come. Despite study tor operations to effect their control, buttesting, NRTS-style, was growing. No periods of up to three years, none of either fully inserted or fully removed.matter where he looked around the several responses met the Navysdesert, Ginkel could observe an impres- demanding requirements within a rea- Another ground-breakingand aesthet-sive array of activity. sonable cost or time. It appeared that ically satisfyinginnovation in thethe aluminum-clad/enriched-uranium ATR was how it wrapped the reactorsAt the Test Reactor Area, the Navy was reactor concept might have reached its fuel around the samples in serpentineemerging as Phillips major customer, limit of performance. 5 fashion, more than doubling the neu-and a third big testing reactor was on tron flux (available in the ETR) to thethe way. The Navys nuclear fuels were The Navy asked Phillips to take two sample. As deBoisblanc relates, it wasgetting more complex, and the Navy months to review previous proposals during the long drive home from thewanted a test reactor with more preci- and come up, if possible, with a con- Site that the Aha! moment occurred.sion than the ETR. It wanted to test ceptual design. This challenge handedfull-scale fuel elements, which were NRTS people a chance to prove they As was the custom, I was driving Byrongetting larger and thicker, not just sam- could still produce brilliant ideas. One Leonard, our consultant fromples. Also, it wanted faster results, of them, Deslonde deBoisblanc, a sci- Internuclear Company, to his hotel in16 0'