In the presence of tri-n-octyl-phosphine (TOPO) oxide, 3-phenyl-4-benz
oyl-5-isoxazolone (PBI) has been found to be a promising chelate extra
ctant for the partitioning of actinides from acidic nuclear waste solu
tions. Quantitative extraction of Pu and U is possible in the nitric a
cid concentration range 1-6 M, whereas Am can be extracted only from s
olutions with an acidity < 2 M. Extraction studies of Am and U under v
arying loading conditions are also carried out and conditions for quan
titative stripping are arrived at.