Examination of an instrumented fuel element after dryout tests in Winfrith SGHWR

Examination of a fuel element that had been subjected to dryout tests in the Winfrith steam generating heavy water reactor proved it to be in good condition. There was clear evidence of cladding softening attributable to dryout overheating on several pins, and the boundaries of the softened zones were determined by hardness measurement. There was, however, no suggestion that softening of the cladding had adversely affected integrity of the fuel element. Annealing tests on cladding from selected regions of the pins led to estimated values for dryout temperatures that were consistent with those measured in-reactor. (author)