A new decladding-dissolution process was developed for zirconium-clad uranium metal and UO2 fuels. The proposed penetrate-leach process consists of penetrating the zirconium cladding with Alniflex solution (2M HF-1M HN0 3-1M A1(N0 3) 3-0.1M K2Cr207) and of leaching the exposed core with 10M HNO3. Undissolved cladding pieces are discarded as solid waste. Periodic HF and HNO3 additions, efficient agitation, and in-line zirconium analyses are required for successful control of ZrFi* and/or AIF3 precipitation during the cladding-penetration step. Preliminary solvent extraction studies indicated complete recovery of uranium with 30 vol % tributyl phosphate (TBP) from both Alniflex solution and blended Alniflex-HN03 leach solutions. With 7.5 vol % 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 UZr3 (epsilon phase of uranium-zirconium system) on the safety of penetrate-leach dissolution was investigated.