Effects of internal surface flaws, iodine concentration and temperature on the stress corrosion cracking behavior of Zircaloy-4 tubing (LWBR Development Program)

Technical Report · Sun Feb 01 04:00:00 EST 1976

OSTI ID:7363742

Tucker, R P; Kreyns, P H; Kearns, J J

Iodine stress corrosion cracking (SCC) in unirradiated stress-relieved Zircaloy-4 tubing specimens internally pressurized with argon gas to produce hoop stresses from 25,000 to 50,000 psi is evaluated experimentally in terms of the effects of internal surface flaws ranging from pits to grooves, of iodine concentrations between 0.05 and 4 mg/dm/sup 2/ Zircaloy surface and of test temperatures of 680/sup 0/, 720/sup 0/ and 750/sup 0/F on the time-to-failure. These data are analyzed in the framework of a fracture mechanics model for iodine vapor SCC. A reasonable correlation is demonstrated between minimum iodine SCC lifetime and surface flaw characteristics. Lifetime is determined to vary inversely with iodine concentration to the 3/4 power. An expression relating the iodine SCC threshold stress in Zircaloy-4 tubing to temperature, iodine concentration and surface flaw characteristics is presented. Test results are given corroborating the prediction expression for threshold stress.

• Research Organization: Bettis Atomic Power Lab., West Mifflin, Pa. (USA)
• OSTI ID: 7363742
• Report Number(s): WAPD-TM-1248
• Country of Publication: United States
• Language: English

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