[en] The results of studies conducted in support of the U.S. Nuclear Regulatory Commission's review of the Preliminary Safety Analysis Report for the Clinh River Breeder Reactor are summarized. In particular, three aspects of the unprotected transient overpower accident are examined. The first aspect is the response of the Clinch River Breeder Reactor to low reactivity insertion rates. Second, the investigation of a new method for computing the time, place and mode of fuel pin failure is studied. Lastly, the question of post-failure fuel freezing and plateout is addressed. Several areas of uncertainty in the analysis of these accidents are also discussed