MODIFIED ZIRFLEX PROCESS FOR DISSOLUTION OF 1-10% U-Zr ALLOY FUELS IN AQUEOUS NH$sub 4$F-NH$sub 4$NO$sub 3$-H$sub 2$O$sub 2$: LABORATORY DEVELOPMENT

A modified Zirflex process was developed in the laboratory for dissolution of 1 to 10% uranium-zirconium alloy fuels to produce a nitrate solution from which uranium can be recovered by conventional solvent extraction methods. A flowsheet is presented for dissolution of 7% uraniumzirconium alloy in 5.4 M NH/sub 4/F-0.33 NH/sub 4/NO/sub 3/. Enough 1 M A/sub 2/O/sub 2/ is added continually during dissolution to yield 0.13 M H/sub 2/O/sub 2/ in the final solution, neglecting the amount reacting. Dissolution is complete in 1 hr. The solvent extraction feed is prepared by adding aluminum nitrate and nitric acid to the dissolver solution to yield a stable solvent extraction feed solution of 0.0075 M uranium, 0.25 M zirconium, 1 M aluminum, 2 M fluoride, and 1 M HNO/ sub 3/. The off-gas is approximately 98.5% NH/sub 3/, 1% H/sub 2/, 0.3% O/sub 2/ , and 0.1% N/sub 2/. Conventional stainless steel such as 309SNb, Ni-o-nel, or Hastelloy F appears to be a suitable material of construction with corrosion rates varying from 0.1 to 3.0 mils/month. (auth