Analysis of iodine stress corrosion cracking of Zircaloy-4 tubing (LWBR Development Program)

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

OSTI ID:6720058

Kreyns, P H; Spahr, G L; McCauley, J E

A fracture mechanics approach to interpreting iodine-vapor stress-corrosion cracking (SCC) in unirradiated Zircaloy-4 tubing is presented in which crack velocities are related to the fourth power on the stress intensity factor, K/sub I/. The crack growth power law on K /sub I/ is shown to predict well the time-to-failure in internally pressurized Zircaloy-4 tubing at 360 and 400/sup 0/C reported by Busby, Tucker and McCauley. The temperature dependency on iodine stress corrosion cracking in Zircaloy can be described by an Arrhenius-type equation in which the activation energy Q for recrystallized and cold-reduced Zircaloy was determined to be 42.9 kcal/mole and 35.9 kcal/mole, respectively. It is concluded that the geometry of the initial surface flaw, through its attendant elastic stress field, is directly responsible in controlling the SCC time-to-failure, cold working having a relatively small effect on increasing the susceptibility to SCC. Any effects of the fast neutron flux on iodine stress corrosion cracking of Zircaloy-4 tubing either in-reactor or out-of-pile are still unknown. (NSA 33: 26510)

• Research Organization: Bettis Atomic Power Lab., West Mifflin, PA (USA)
• OSTI ID: 6720058
• Report Number(s): WAPD-TM-1203
• Country of Publication: United States
• Language: English

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