b'C H A P T E R 12R EA CT O R S B E G ET R EA CT O R Score of a reactor, it was essential to The AEC authorized Phillips to build a The small reactor, the first of manyknow whether the reactor would create second reactor at the MTR site, the low-power reactors at the Site, comple-more fuel than it consumed and how Reactivity Measurement Facility mented the MTR in that it had a highlong the doubling time would be. If (RMF). Started up in February 1954, sensitivity to subtle changes in reactivi-the process were to take forty years or this was a small, very low-power reac- ty. The RMF functioned as a detectormore, the commercial economics were tor located in the east end of the MTR of neutrons, whereas the large MTRfar less attractive than if the process canal. Water was its moderator, reflec- functioned as a source of neutrons.took, say, fifteen years. Bruggers work tor, and shield. The RMF used the same The two functions could not be maxi-meant that reactor designers could kind of fuel assembly as the MTR, but mized in the same reactor. The RMFselect fuels and other materials with operated only at power levels of one or enabled analysts to assay new and spentsome confidence that the reactor would two hundred watts.be economically viable. Consequently,scientists from all over the world beat apath to the door of the NRTS.Phillips scientists made many othermoves to expand the capabilities of theMTR. Engineers added a hydraulicrabbit, which allowed them to run Right. Technician demonstrates removal of a fuelspecimens into the reactor without shut- element from cask. Crane holds lid while workerting it down. Argonne installed a high- uses special tool to remove element. Cask held sixtemperature, high-pressure circulating to eight elements. Below. The MTR canal containedwater loop in position HB-2 of the reac- the small Reactivity Measurement Facility, a low-tor. This permitted a specimen to be power reactor. The flat plate in front is a boron-exposed to neutron flux along with aluminum control element. Samples to be measuredhigh-temperature circulating water. The went into a water hole, here filled with a plug.complex apparatus included a heat INEEL 55-1989exchanger, pumps for circulating thewater, and the means of regulating tem-perature, pressure, and other parametersin the water. A Hot Cell Building wentinto use in the summer of 1954.Operators, shielded behind thick con-crete walls and special viewing win-dows, could handle, photograph, mill,measure, and weigh radioactive samplesusing remotely operated manipulators. 12INEEL 56-36971 1 1'