Work is reported on corrosion studies of candidate materials of construction for equipment for the dissolution of Zircaloy cladding in NH/sub 4/F- NH/sub 4/NO/sub 3/ solutions, the total dissolution of suainless steel clad fuels in HNO/sub 3/-HF solutions, and the dissolution of stainless steel cladding in dilute H/sub 2/SO/sub 4/. A single material of construction which could be used for a processing complex which would handle all of the low-enrichment fuels concerned was searched for. In the Zirflex Process (NH/sub 4/F-NH/sub 4/NO/sub 3/ ) the 300 series stainless steels, vacuum-melted Hastelloy-F, Carpenter 20, Nio- nel, Haynes 25, and Incoloy 804 have satisfactory corrosion resistance to solutions involved in the dissolution of Zr or Zircaloy claddings. Satisfactory dissolution rates for 304-L stainless steel cladding are obtained in the Niflex Process (1MHNC/sub 3/-2MHF) solutions. The minimum practical fluoride to stainless steel ratio is about five. Among many materials studied, vacuum-melted HastelloyF offers the best corrosion resistance to HNO/sub 3/-HF solutions encountered during decladding. In the Sulfex Process (H/sub 2/SO/sub 4/) dissolution rates for both annealed 304-L and 347 stainless steel in 3 to 3 M H/ sub 2/SO/sub 4/ are from 5 to 10 mils per hour. Vacuum-melted Hastelloy-F and Ni- o-nel …

Reprocessing of the ARE fuel was resumed after extensive leak testing in the pilot plant. This was considered necessary to assure no recurrence of gaseous UF/sub 6/ leaks as experienced in Run E-2. In the four additional runs required to complete the program, about 641 kg of fluoride salt containing 40.64 kg of fully enriched uranium was reprocessed. Recovery as UF/sub 6/ product represented 97.97% of the feed, with 0.01% measured losses. An additional 2.14% was reclaimed from NaF beds. The product was of sufficient purity to meet specifications for material designated for reduction to uranium metal. Decontamination from fission products was essentially complete. Calculations based on the entire ARE program indicated 96.38% product recovery, with 0.06% measured losses. An additional 2.50% was reclaimed from NaF beds and equipment washes. (auth)