Title: Penetrate-leach dissolution of zirconium-clad uranium and uranium dioxide fuels
Abstract: A new decladding-dissolution process was developed for zirconium-clad uranium metal and UO/sub 2/ fuels. The proposed penetrate-leach process consists of penetrating the zirconium cladding with Alniflex solution (2M HF--1M HNO/sub 3/--1M Al(NO/sub 3/)/sub 3/--0.1M K/sub 2/Cr/sub 2/O/sub 7/) and of leaching the exposed core with 10M HNO/sub 3/. Undissolved cladding pieces are discarded as solid waste. Periodic HF and HNO/sub 3/ additions, efficient agitation, and in-line zirconium analyses are required for successful control of ZrF/sub 4/ and/or AlF/sub 3/ precipitation during the cladding-penetration step. Preliminary solvent extraction studies indicated complete recovery of uranium with 30 vol. percent tributyl phosphate (TBP) from both Alniflex solution and blended Alniflex-HNO/sub 3/ leach solutions. With 7.5 vol. percent TBP, high extractant/feed flow ratios and low scrub flows are required for satisfactory uranium recovery from Alniflex solution. Modified waste-handling procedures may be required for Alniflex waste, because it cannot be evaporated before neutralization and large quantities of solids are generated on neutralization. The effect of unstable UZr/sub 3/ (epsilon phase of uranium-zirconium system) on the safety of penetrate-leach dissolution was investigated.