Direct dissolution of intact UO2 pellet and in situ extraction by organic solutions of TBP-HNO3 at atmospheric pressure. Role of solvate composition

Recently authors demonstrated direct dissolution of g-level PHWR UO2 fuel pellet fragments and in situ extraction by TBP-HNO3 and TiAP-HNO3 solutions at atmospheric pressures. Extending the work, similar studies were performed on intact unirradiated PHWR UO2 fuel pellets (∼15 g U) with varying compositions of organic solvate of tri-n-butyl phosphate (TBP). It was observed that extent of dissolution was a strong function of organic solution composition TBP x (HNO3)x (H2O)y. Complete dissolution of intact UO2 pellet in a reasonable time was observed only in case of a particular solvate composition. (author)