Role of laves intermetallics in nuclear waste disposal 1 1 This paper has been created by the University of Chicago as Operator of Argonne National Laboratory (“Argonne”) under Contract No. W-31-109-ENG-38 with the US Department of Energy.

Abstract Laves intermetallics (AB 2 compounds) play an important role in the disposal of metallic waste resulting from the electrometallurgical treatment of spent nuclear fuel. These ZrFe 2 -type intermetallics incorporate and immobilize highly radioactive and long-lived constituents that are present in waste forms based on the stainless steel–zirconium (SS–Zr) alloys. This paper reviews the metallurgy of SS–Zr alloys with emphasis on Laves intermetallic behavior. Microscopy and diffraction studies have shown that all actinide elements and most fission product elements are present only in the ZrFe 2 -type intermetallics of a stainless steel–15 wt.% zirconium (SS–15Zr) waste form, whereas only molybdenum is incorporated in the ZrFe 2 -type intermetallics of a zirconium–8 wt.% stainless steel (Zr–8SS) alloy. Because of the importance of material durability to waste disposal, recent experiments have been aimed at determining the corrosion behavior of these intermetallics. Results from transmission electron microscopy of corrosion layers observed on the ZrFe 2 -type compounds are presented.

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