DEGRADATION, CLEANUP, AND REUSABILITY OF OCTYLPHENYL-N,N'-DIISOBUTYLCARBAMOYLMETHYL PHOSPHINE OXIDE (CMPO) DURING PARTITIONING OF MINOR ACTINIDES FROM HIGH-LEVEL WASTE (HLW) SOLUTIONS

The radiolytic degradation of the extractant mixture 0.2 M octylphenyl -N,N'-diisobutylcarbamoylmethyl phosphine oxide (CMPO) + 1.2 M tributy l phosphate in n-dodecane [to be utilized for the partitioning of mino r actinides from high level waste (HLW) solutions of PUREX origin] has been investigated in contact with 3 M HNO3 or synthetic pressurized h eavy water reactors (PHWR)-HLW solution under dynamic conditions. The distribution ratios of Am, Zr, Fe, and Ru with the irradiated extracta nt mixture at varying doses have been determined under various aqueous phase conditions and correlated with the formation of degradation pro ducts. Various cycles of loading the extractant mixture with Am from P HWR-HLW, irradiating at a fixed gamma dose, and then primary and secon dary clean-up of the solvent has been carried out to illustrate its re usability during partitioning of minor actinides from actual HLW solut ions. The degradation products of CMPO have been identified by employi ng GC and GC-MS techniques.