Study On The Effect Of TBP Degradation Products On The Co-decontamination Cycle Of Purex Process

Although it has a high recovery rate for uranium and plutonium,in the actual process,because TBP can produce radiolysis products due to radiation degradation,these radiolysis products will have a negative impact on the decontamination of some fragmented elements,and these radiolysis products will form Interfacial crude with fission products.In severe cases,it will affect the normal operation of the extractor,resulting in a reduction in the recovery rate of uranium and plutonium,and the extraction process cannot reach the predefined goals.At present,when scholars at home and aboard are studying the influence of TBP degradation products on the co-decontamination process,they mostly focus on the Interfacial crude as the major research direction,the research is mainly based on single fragment elements,and the research methods are mostly carried out by single-stage extraction.In this topic,by combining single-stage extraction and multi-stage extraction,in a multi-element mixed simulation feed liquid,it discusses the effect of TBP degradation products on the co-decontamination process from the aspects of decontamination efficiency and interface impurity.The main research conclusions are as follows:（1）A single-stage experiment was conducted to explore the impact of TBP degradation products on the decontamination effect of zirconium and ruthenium.The results show that in the presence of TBP degradation products it will be conducive to the decontamination of ruthenium by heating,increasing acidity,and increasing uranium concentration,while it will be conducive to the decontamination of zirconium by reducing acidity and increasing uranium concentration.With increase of（HDBP）concentration,it will reduce the decontamination effect of zirconium and ruthenium to a certain extent;（2）Through a single-stage experiment,it uses Ce to simulate mixed solution,such as Pu,U,Pu,Zr,and Ru to simulate the spent fuel solution,and uses HDBP to simulate the degradation products,and it adopts the single-stage extraction method to study the generation of interphase impurity in the spent fuel solution,all of which gets the basic components of the interfphase impurity,and explores the factors affecting the generation of interphase impurity during the extraction process.The results show that the interphase impurity is composed of uranium,zirconium,cerium and other elements;with the increasing of concentration of uranium and zirconium,it promotes the formation of interphase impurity,and the concentration of cerium has little effect on the formation of interphase impurity,while acidity will inhibit the formation of interphase impurity.As the acidity of the system increases,it will decrease the amount of interphase impurity generated.（3）Through bench experiments in mixer-settler,it explores the influence of TBP degradation products on the co-decontamination process.The results show that with the increasing the number of degradation products of TBP in the system,it will decrease the decontamination efficiency of zirconium and ruthenium,and the amount of generated interphase impurity increases with the increase of the concentration of HDBP and H₂MBP,among of which,H₂MBP will promote the formation of interphase impurity,it is wider for the generation scope of interphase impurity in the mixer-settler,and there are more stages.It analyzes the mixed solution in the extraction process,which obtained the distribution of each material in the mixed clarifying tank.Therefore,it is found that there is a material accumulation effect in the extraction process in the mixed clarifying tank.