Reactivity accidents with the potential for catastrophic fuel damage

A review is presented of light-water-reactor event sequences that have been investigated for their potential to result in reactivity accidents with catastrophic fuel damage, i.e., fuel fragmentation and loss of coolable geometry. This review considers studies in the United States and abroad which were an outgrowth of the concern after the accident at the Chernobyl plant in the Soviet Union. The work in the United States was primarily done for the Nuclear Regulatory Commission to reconfirm or bring into question previous judgments on reactivity events that must be analyzed for licensing and to determine if any events needed more analysis in the context of severe accident research. The review discusses event sequences that have been identified and the corresponding probabilistic and deterministic analyses. Judgments are given as to which events are important and which may require further investigation or action.