Delayed Hydride Cracking in Zircaloy Fuel Cladding - An Iaea Coordinated Research Programme

The first step for delayed hydride cracking in zirconium alloys

“…This observation is consistent with the experimental observation that K IH increased for these data beyond the stress intensity factor for the applied loads [63,64]. Similar high-temperature data have been observed for Zircaloy-4 [65], and likewise predictions made with the steady-state solution do not match well above the high-temperature DHC limit, which happens at approximately 300°C for Zircaloy-4 (c.f. %350°C for Zr-2.5Nb, Fig.…”

Molecular dynamics simulations of liquid crystalline phases of dodecyltrimethylammonium chloride

“…For some cases of HE, hydride formation plays a central role in the detoriation process. A hydride is a brittle non-metallic phase that may cause the embrittlement of metallic materials such as titanium-and zirconium-based alloys and reduce their load bearing capabilities (Coleman and Hardie 1966;Coleman et al 2009;Chen et al 2004;Luo et al 2006). For metal based components exposed to hydrogen-rich environments, such as fuel cladding materials in nuclear power reactors or components in rocket engines, there is an impending risk of hydrides forming, which could lead to the so called delayed hydride cracking (DHC).…”

“…For metal based components exposed to hydrogen-rich environments, such as fuel cladding materials in nuclear power reactors or components in rocket engines, there is an impending risk of hydrides forming, which could lead to the so called delayed hydride cracking (DHC). This is a subcritical crack growth mechanism (Coleman et al 2009;Singh et al 2004;Coleman 2007;Northwood and Kosasih 1983) that can severely reduce the component life-time and jeopardize its integrity.…”

Applications to CANDU Reactors

“…4. Under-cooling temperature below the TSSD temperature during reactor cooldown at which DHC crack growth starts, with the TSSD temperature calculated according to item (2).…”

“…An example is the current effort of an IAEA Coordinated Research Programme on the measurement of DHC growth rate in fuel cladding material [2] that was preceded, as an initial step, by a similar study on pressure tube material [11].…”