Modeling of Zircaloy cladding primary creep during load drop and reversal

In this paper we derive a simple and easily implementable set of rules for primary creep based on experimental results which contradict the strain hardening rule. The primary creep predicted by these rules is compared with data from published thermal creep experiments and Halden in-pile creep experiment IFA-585. The model thus created is shown to perform well in describing both transient stress scenarios with monotonously increasing stress and scenarios involving load drops and reversals.