b'C H A P T E R 6N E U T R O N S : F AS T F LU X , H I G H F LU X ,A N D R I C KO V E RS F LU XThe majority of the MTRs experiments Curved plates? Over time would the If they could tuck the sample near thewould be more like Argonnes tar-mak- fuel element shrink or stretch? Bend core of the reactor and subject it to asing investigation. The nuclear commu- inward or outward? Crumble? The many neutrons in a week as it wouldnity needed to learn a great deal more cladding had to protect the fuel and otherwise receive in a year in a regularabout how the fission environment prevent the fission productsthe reac or , physicists could learn quickly if twould affect the materials of which the radioactive krypton and barium and radiation would damage the material,reactor was made, including the urani- other elementsfrom escaping into the and if so how soon and how badly. Ifum fuel. The work of its neutrons was coolant or the environment. they irradiated a sample fuel element,to bombard and irradiate. they would learn exactly how a curvedThen there were endless questions about fuel plate made of a certain alloy wouldUranium could take the form of a solid, coolants and piping. Was there a liquid shrink or expand or bend. Aside from itsgas, or liquid. Which would be the metal more convenient and safer than generous neutron flux, the defining char-best? How long would a fuel element NaK? Advancing the art and science of acteristic of the MTR was the fact that itlast before it lost its reactivity? How nuclear reactors required answering one had about a hundred sample holes. 11would fission-product build-up affect question after another, building a wholethe ability of the fuel to do its work? new body of knowledge. Scientists at the Clinton Laboratory atWhat kind of beta or gamma radiation Oak Ridge had been working on thewould result from the decay of fission The way to start was to bombard candi- high-flux reactor since 1944. It calledproducts? What was the best shape for date materials with neutrons in the for highly enriched uranium fuel and anfuel elements? Rods? Flat plates? MTR, and the more neutrons the better. operating power level of 30 megawatts.Early MTR Site Plan showssubstantial complex of supportbuildings required to operate areactor. For safety, hotfunctions were on one side of interior exclusion fence,while cold functions were onthe other.4 9'