PYROPHORICITY OF URANIUM IN REACTOR ENVIRONMENTS

Current information relative to the pyrophoricity of uranium is reviewed and aspects of this troublesome phenomenon which can support further investigation are considered. Information on metallic uranium fuel element fires, up to the present, provide an inadequate base for extrapolation to future operations because of existing uncertainty with respect to causative mechanisms and fire control techniques. Experience at Hanford reactors indicates conditions which tend to reduce the fuel element fire hazard. These include minimizing of the in-core residence time of a fuel element with a cladding defect which permits uranium corrosion, employment of removal and discharge techniques which do not contribute to the deterioration of the fuel element, and minimizing of the time interval between discharge and entry into the retention basin. (J.R.D.