Abstract
High concentration of uranium present in high‐level waste is responsible for third phase formation during actinide partitioning either by TRUEX or DIAMEX process. Di(2‐ethylhexyl) pivalamide (D2EHPVA) has been found to be a promising extractant for the selective removal of U over Pu, Np, and Am from simulated PHWR high level waste (SHLW). Role of reducing agents viz. hydroxylamine nitrate (HAN) and hydrazine nitrate (HN) has been evaluated for the adjustment of oxidation states of Pu and Np to inextractable state. Multiple extraction from SHLW containing 0.3 M HAN + 0.8 M HN at 4 M HNO3 using 1 M D2EHPVA in n‐dodecane revealed that ∼98% of U could be extracted in five contacts with <1% cumulative Pu extraction.