Studies of the role of molten materials in interactions with UO/sub 2/ and graphite. [GCFR type reactors]

Graphite, which is being considered as a lower reactor shield in gas-cooled fast reactors, would be contacted by core debris during a core disruptive accident. Information on the interaction of graphite, UO/sub 2/, and stainless steel is needed in assessing the safety of the GCFR. In an ongoing study of the interaction of graphite, UO/sub 2/, and stainless steel, the effects of the steel components have been investigated by electron microprobe scans, x-ray diffraction, and reaction-rate measurements. Experiments to study the role of the reaction product, FeUC/sub 2/, in the interaction suggested that FeUC/sub 2/ promotes the interaction by acting as a carrier to bring graphite to the reaction site. Additional experiments using pyrolytic graphite show that while the reaction rate is decreased at 2400 K, at higher temperatures the rate is similar to that using other grades of graphite.