Abstract: "The corrosion rate in 680 F water of the uranium-50 w/o zirconium binary alloy was found to be -0.20 mg/(cm2)(hr), and that of the uranium-40 w/o zirconium binary alloy was -0.34 mg/(cm2)(hr). Both alloys correlated uniformly, with no evidence of discontinuous failure. Normal variations in interstitial content in either alloy had no significant effect on corrosion behavior. Tantalum additions, in the range of 0.2 to 5 w/o, improved the corrosion rate of the uranium-50 w/o zirconium base, with a minimum rate of -0.06 mg/(cm2)(hr) for the 5 w/o tantalum alloy. The 5 w/o tantalum addition to the uranium-40 w/o zirconium alloy. The 5 w/o tantalum addition to the uranium-40 w/o zirconium alloy decreased the corrosion rate of the base to -0.11 mg/(cm2)(hr) in the [...] condition only. In either conditions, the 5 w/o tantalum alloy failed discontinuously. All other additions to both bases either had no effect or decreased corrosion resistance. These included aluminum, chromium, iron, molybdenum, nickel, platinum, tin, titanium, tungsten, and vanadium additions."

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Dr. Laurence opened the discussion by saying that AECL is concentrating its interest on fuel rods for NRU to be ready at the end of the year; these will be unbonded, based on NRX experience. Chalk River, however, is prepared to go to bonded fuel elements,and how has in extrusion cladding at AlCan an alternate process. AECL is putting its trust in extrusion clad flat plates for the immediate future. General Electric Co. of Canada is now making UO{sub 2} fuel rods; these are UO{sub 2} pellets machined and threaded into a sheath. They are hoped to be useful for higher temperature operation.

Calculations are presented regarding the effect of delayed neutrons in reactors fueled with mixtures of Pu²³⁹ and U²³⁵. Results are plotted to illustrate the change in thermal flux as a function of time for various positive or negative step changes in reactivity.