Power Reactor Spent Fuel Reprocessing PUREX Process Simulation

In order to cope with the energy crisis,China is developing nuclear power on a large scale,however,while the large-scale nuclear power in China brings huge electric energy to the country,the nuclear power operation process also generates a large amount of spent fuel,and since there are elements such as uranium(U)and plutonium(Pu)available in the spent fuel and China upholds a closed-cycle strategy for nuclear fuel,it is necessary to reprocess the spent fuel to extract uranium(U)and plutonium(Pu)(Pu)and other elements.In the long history,there are many processes for reprocessing spent fuel,but most of them have been abandoned due to more or less disadvantages,while the PUREX process is the mainstream reprocessing process at home and abroad because of its high efficiency,low waste liquid volume,economy and reliability.Due to the presence of large amount of radioactive elements in the spent fuel during the experimental verification of PUREX process and industrial production,which will continuously release radiation to the outside and will adversely affect the experimental personnel and industrial production personnel,based on this,it is necessary to conduct numerical simulation in the design,construction and operation of reprocessing plants.In this thesis,we have developed a partition ratio model,a chemical reaction model,and a mass transfer model for the physical,chemical,and hydrodynamic properties of the extracted components in the PUREX process based on a large amount of domestic and international literature on the PUREX process.In the partition ratio model,the partition ratio of the extracted components is related to the temperature,extractant concentration,acidity and other factors;in the chemical reaction model,the chemical reaction model of U,Pu and HNO3 is established,and the data calculated by the model are compared with the experimental data,and there are 6.8% and 9.8% gaps,i.e.,the model data can better match the experimental data,and the model is in line with the reality..In the mass transfer model,the established n-element linear equation system is expanded in the form of a matrix,and the pi and xi in the matrix have interdependent relationships,so the iterative method can be used to find xi;the model is written in Fortran language as a distribution ratio module and a mass transfer module,and the post-processing simulation program is constructed,and the modular program is simple and easy to read.The constructed program was used to simulate four different states of TBP extraction with high concentration of Pu(IV),TBP extraction with low concentration of Pu(IV)-Pu(VI),reduction of Pu(IV)by hydroxylamine nitrate,and TBP extraction with Np(V)-Np(VI),and compared with the experimental data published in the literature,it was found that the difference between the simulated and experimental values was basically less than 10% for TBP extraction and the composition in the washing solution.The simulated values basically obeyed the experimental values better,The mass transfer model is realistic;however,in the simulated chemical reactions,the program does not converge,the simulated results were only approximately the same as the experimental values in terms of increasing or decreasing trends,and there was still a certain gap between the two numerically,which might be related to the deviation of the simulated chemical reaction rate from the actual chemical reaction rate.Later,by setting more suitable chemical reaction rate parameters,the program should not only be consistent with the experimental values in terms of trend,but also in terms of overall values when simulating chemical reactions.