In-Pile Photographic Studies of EBR-II Mark-I and Fermi Core—A Sample Meltdown

Fast reactor fuel sample meltdown experiments have been performed, in the TREAT reactor, with high speed color photography. EBR-II Mark-I and half-length Enrico Fermi Core-A type elements have been studied. In addition, preliminary experiments have been performed on EBR-II size UO₂ samples. Sample conditions at the times of failures, types of failures, and rates of emission of material from the elements have been obtained. Course of failure following the initial emission of material is obscured, in the EBR-II sample case, by release of “clouds” of sodium originally present inside the element to effect a thermal bond between fuel and cladding. Photographic results were found to be consistent with previous deductions on sample failures obtained from opaque meltdown experiments.