Np의 산화제로 1g/L NH₄VO₃ 함유된 10 성분계의 모의방사성 폐액으로부터 Re, Np 및 잔존 U만을 선택적으로 분리하기 위하여 TBP에 의한 이들의 공추출과 역추출 거동 규명 및 이의 조업조건을 고찰하였다. Re, Np, U의 공추출 조건으로는 TBP의 농도를 증가시키는 것보다 O/A 비를 2정도로 증가시키는 것이 효과적이다. 그리고 Re, Np, U 등이 공추출된 유기상으로부터 NBA에 의해 Np만을 선택적으로 환원 역추출할 수 있으며, 조건으로는 Np이 67% 역추출되는 NBA=1.04M, O/A=1이 적당하다. 이때 Re이 70% 정도 Np과 같이 공역추출되므로 Np의 분리에 앞서 Re을 미리 제거시켜야 한다. 한편 Re의 선택적 역추출은 O/A 비 변화를 통한 Np의 공역추출 감소가 요구되고 있으며, Re 및 Np이 각각 80%, 6%로 역추출되는 5M 질산, O/A=4가 적당하다. 반면에 U의 선택적 역추출은 U의 분리에 앞서 Re과 Np을 미리 제거시켜야 하며, 0.01M 질산, O/A=7에서 약 76%의 U이 역추출되었다.

For the selective separation of Re, Np and residual U from the 10 components simulated radwaste solution containing the NH4VO3 of 1 g/L as an oxidant of Np, the behavior of co-extraction by tributyl phosphate/n-dodecane and stripping of Re, Np, U and their operation conditions were evaluated. Co-extraction of Re, Np and U was more effective increase of O/A ratio than with increase of TBP concentration. Co-extraction yields of their elements were 28.6%, 93.8% and 96.2% at O/A=2, respectively. It was found that Np was effectively stripped by reduction with a NBA (normal butyraldehyde) from the loaded organic phase. At 1.04 M NBA and O/A=1, Np and Re was co-stripped about 67% and 70%, respectively. So, Re must be removed before separation of Np. Stripping of Re, however, was needed the decrease of the co-stripping yields of Np with change of O/A ratio. At 5 M HNO3 and O/A=4, Np and Re was co-stripped about 80% and 6%, respectively. On the other hand, Re and Np must be removed before separation of U. U was stripped about 76% at 0.01 M HNO3 and O/A=7.

Rhenium Neptunium Uranium Oxidation/Reduction Tributyl Phosphate

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