Neptunium distribution in a high acid first cycle Purex Process

Behavior of Neptunium in HNO3-HNO2 System (A Simulation Experiment for Dissolution of Spent Fuel Elements)

“…This situation arises from complicated behavior of neptunium in nitric acid which could exist as Np(IV), Np(V) and Np(VI) of different stability. The essential task for reprocessing is to separate and recover plutonium and uranium, meanwhile it is not easy to find such a salt-free reagent so as to convert neptunium selectively and quantitatively to less extractable Np(V) and stabilize it in HNO3 solution, finally it may direct neptunium into one single stream [1][2][3][4][5][6][7][8][9][10][11][12], Since the eighties, many efforts have been made to improve removal of neptunium in the PUREX process. The reductants, such as n-butyraldehyde, iso-butyraldehyde, organic derivatives of hydrazine and hydroxylamine and photochemical method were tested [13][14][15][16][17][18][19][20][21], but for practical use in the reprocessing plant it still needs exhaustive investigation.…”