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Specific Zirconium Alloy Design Program Quarterly Progress Report: Fifth Quarter, April - June, 1963

Description: A program is in progress for the design of a zirconium base alloy for steam service as nuclear fuel cladding. Thirty-one alloys selected for study of corrosion rate, hydriding rate and hydrogen embrittlement are in test. The corrosion testing of 1800 coupons to 3000 hours at at 300, 400, and 500 degrees C in refreshed steam has been completed. Statistical data analysis of the corrosion results are reported and alloys showing better corrosion performance at all test temperatures than that for Zircaloy-1 are discussed. Preliminary data for hydrogen uptake after long exposures at 400 and 500 degrees C are presented; the uptake for alloys showing the best corrosion performance is discussed. Post-corrosion mechanical property measurements are also reported along with the preliminary results of x-ray diffraction and metallographic studies relating to hydrogen embrittlement. A wide variation in resistance to embrittlement at a given hydrogen level was observed and can be tentatively correlated with original ductility, crystallographic texture, and hydride platelet orientation. The testing of a second round of ten alloys is also in progress. Studies concerning the mechanism of corrosion and hydriding in zirconium alloy are also reported. The results of recent neutron activation analyses of stripped corrosion films are presented. Oxygen diffusion through doped non-stoichiometric ZrO2 is now proceeding following earlier difficulties in sample preparation. Work on hydrogen overvoltage and electrochemical potential of inter-metallic phases was previously completed and reported.
Date: July 1, 1963
Creator: Klepfer, H. H.; Jaech, John L.; Blood, R. E. & Douglass, D. L. (David Leslie), 1931-
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Specific Zirconium Alloy Design Program Quarterly Progress Report: Seventh Quarter, October - December, 1963

Description: Summary: All experimental work under the Corrosion Mechanism task has been completed. The remaining topical reports are being prepared by D. L. Douglass, now on assignment at Mol. Experimental work on the first round of 31 alloys and on the second round of 10 alloys has been completed. Steam exposures of at least 3000 hours were finished for all the alloys at all test temperatures, with exposures of some coupons to 6700 hours. Mathematical expression have been derived to describe all first round data for corrosion rates and hydriding rates at 300, 400, and 500 degrees C as a function of Nb, Cr, Fe, and Cu content. Solution of the equations for particular service temperatures yield Zr-Cr alloys at optimum at lower temperatures and Zr-Cu-Fe alloys as optimum at the higher temperatures. The second round test results show that neither Ni nor Be additions to Zr-Cr or Zr-Cu improve the performance over that of the optimum Zr-Cr or Zr-Cu-Fe alloys. For the first round heat treatment used, post-corrosion ductility depends on two factors in addition to alloy composition and hydrogen content: crystallographic texture and intermetallic aging reactions. Alloys with a high original ductility are embrittled less by a given amount of hydrogen than are alloys with low original ductility. From the second round tests, it was found that raising the final alpha annealing temperature from 565 to 788 degrees C gives better over-all corrosion, hydriding performance, and resistance to hydrogen embrittlement for both the Zr-Cr and Zr-Cu alloys tested.
Date: January 1964
Creator: Klepfer, H. H.; Jaech, John L.; Blood, R. E.; Perrine, H. E. & Urata, M. E.
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Specific Zirconium Alloy Design Program Quarterly Progress Report: Sixth Quarter, July - September, 1963

Description: Summary: Fundamental studies in support of the alloy design work are complete except for the experimental determination of the diffusion of oxygen in alloy-doped non-stoichiometric ZrO2. Over 100 oxidation runs have now been made on samples of ZrO2 doped with 1 mole percent of the oxides of Al, Y, Fe, Cr, and Ni. The first round testing of 31 alloys is now essentially complete. Analysis of the steam corrosion rate and hydriding raw data taken at 300, 400, and 500 degrees C indicates that Zr-Cr and Zr-Cu-Fe alloys show the most promise for development for service in steam over the entire temperature range 300-500 degrees C. Maximum resistance to corrosion hydrogen embrittlement requires high initial ductility and thus low, perhaps less than ~2.5 a/o total alloy content. For any composition, susceptibility to hydrogen embrittlement depends on crystallographic texture of the component; under certain circumstances hydrogen embrittlement may be high anisotropic. The second-round testing of 10 selected Zr-Cr and Zr-Cu base alloys is now about 50% complete. Three alternate fabrication schedules were evaluated; and the preliminary results indicate that the Zr-Cu alloy tested is less sensitive to heat treatment than is the Zr-Cr alloy tested. Raising the final alpha annealing temperature from 565 degrees C to 788 degrees C gives better over-all corrosion and hydrating performance for both the Zr-Cr and Zr-Cu alloy tested. Beryllium additions to Zr-Cr or Zr-Cu do not appear to be advantageous. Nickel additions to Zr-Cu do not give an over-all improvement. Nickel additions to Zr-Cu give about the same improvement over Zr-Cu as did iron additions to the Zr-Cu in the first-round test.
Date: October 1, 1963
Creator: Klepfer, H. H.; Jaech, John L.; Douglass, D. L. (David Leslie), 1931-; Blood, R. E. & Perrine, H. E.
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