SEDL / STP / STP633-EB / STP35595S

Hydride Reorientation and Fracture in Zirconium Alloys

Simpson, CJ
Engineer, Nuclear Metallurgy, NDE engineer, and acoustic emission engineer, Ontario Hydro, Research Division, Toronto, Ontario,

Kupcis, OA
Engineer, Nuclear Metallurgy, NDE engineer, and acoustic emission engineer, Ontario Hydro, Research Division, Toronto, Ontario,

Leemans, DV
Engineer, Nuclear Metallurgy, NDE engineer, and acoustic emission engineer, Ontario Hydro, Research Division, Toronto, Ontario,

Pages: 13    Published: Jan 1977

Download this paper for $25 PDF (440K)          View License Agreement
Abstract

Under conditions of high tensile stress, the Zr-2.5Nb alloy has been shown to he susceptible to a very slow crack propagation failure mechanism. This failure mechanism, hydride cracking, has been studied extensively since leaks developed in the pressure tubes of Reactor Units 3 and 4 at Ontario Hydro's Pickering Nuclear Generating Station in Aug. 1974. The failures have been attributed to reorientation and preferential redistribution of hydrides under high tensile stresses, followed by progressive fracture of these hydrides. Mechanical tests, acoustic emission data, and metallographic studies relevant to this mechanism will be presented and related to the occurrence of cracks in the Zr-2.5Nb reactor pressure tubes.