Determining failure thresholds for coated zircaloy claddings in reactivity initiated accidents

The limiting Reactivity Initiated Accident (RIA) Failure thresholds for Zircaloy claddings are generally those related to pellet cladding mechanical interaction (PCMI) in heavily hydrided claddings. The introduction of coatings on the outer surface of Zircaloy cladding mitigates the hydrogen uptake issue and it is likely that this failure mechanism is not applicable to those cladding designs. As such the motivation for new failure thresholds related to high temperature swelling, rupture, and embrittlement mechanisms is described in this summary. Experiments to evaluate these thresholds in a static water capsule in the TREAT reactor at Idaho National Laboratory is then proposed. The experimental capability is described, and preliminary modeling results presented showing the viability of the system.