Multi-objective Optimization Of Parameters For The Components And System In Nuclear Power Plant

Searching higher thermodynamic efficiency of nuclear power plants is a continuous quest in the field of nuclear engineering.Both increasing the thermodynamic efficiency,and decreasing the weight,the volume of nuclear power plants can not only improve the economy,but also reduce the difficulty of manufacture,transport and arrangement of large components.It has been considered important to study the multi-objective optimization design of nuclear power plants,aimed at optimizing the thermodynamic efficiency,the weight and the volume of the nuclear power plant.In the present work,a combined evaluation-optimization model was developed and the multi-objective optimization design of nuclear power plants was studied.An optimizer module has been coupled with a mathematical model for the overall nuclear power system,including both a thermodynamic efficiency calculation model and a weight,volume evaluation model,written in C#.The main contents and results are as follows:1.The research on a novel optimization algorithm.For the multi-objective optimization problem,the performance of the algorithm should be excellent.A novel hybrid artificial bee colony algorithm(NHABC)with better performance was developed by introducing the calculative strategies of the modified compound algorithm and the modified genetic algorithm into the artificial bee colony algorithm.The NHABC algorithm is made up of an artificial bee colony algorithm(ABC),a modified genetic algorithm(MGA)aimed to improve the diversity of ABC algorithm,and a modified compound algorithm(MCA)for performing quickly local search within promising areas(for intensification within promising areas).The NHABC algorithm was tested with 5 unconstrained test functions and 8 constrained test functions.The test results indicate that the NHABC algorithm outperforms other methods for the unconstrained test functions,and the NHABC algorithm is one of the best algorithms for the constrained test functions.Therefore,the NHABC algorithm is helpful to deal with the multi-objective optimization problem of nuclear power plants.2.The research on the component models of a feedwater heater and a moisture separator reheater respectively,and the analyses of the multi-objective optimization results.The feedwater heater and the moisture separator reheater are the main components for thermodynamic efficiency of nuclear power plants.Those weights and volume are also large.Thus,it is necessary to develop the multi-objective optimization design of a feedwater heater and a moisture separator reheater respectively,for carrying out the multi-objective optimization design of nuclear power plants.The reliable physical and mathematical models of a feedwater heater and a moisture separator reheater were set up respectively,written in C#.Combined with the optimizer module,the structural parameters of the feedwater heater have been optimized for minimizing the weights and volume of the feedwater heater and the moisture separator reheater respectively,while satisfying the performance constraints.The multi-objective optimization design were performed.The results show that there is a great deal of potential in decreasing the net weights and the volume of the feedwater reheater and the moisture separator reheater respectively,while satisfying the structural and performance constraints.In parametric analyses of the feedwater reheater and the moisture separator reheater,a detailed explanation for optimized decision parameters of the feedwater heater were given,and the available data permitted to validate both the component models used during the optimization process,and the optimized results.3.The research on the component models of the reactor coolant pump with shaft seal and with canned motor respectively,and the analyses of the multi-objective optimization results.The reactor coolant pump is one of the main and large components.Although,a few of research on the optimization design of the nuclear power system have been developed,the reactor coolant pump is never concerned.It is also necessary to develop the multi-objective optimization design of the reactor coolant pump,for carrying out the multi-objective optimization design of nuclear power plants.The estimation of the size of the reactor coolant pump with shaft seal was formulated as an optimization problem and the optimal decision parameters are found by minimizing the weight and the volume of the reactor coolant pump with shaft seal which is based on the estimation formulations.Then,the reactor coolant pump with canned motor was also optimized,with considering it is generally used in nuclear power plants.The reductions of the weights and volume of the reactor coolant pump with shaft seal and with canned motor respectively are significant.4.The research on the multi-objective optimization design of nuclear power plants.Combined the thermodynamic efficiency calculation model and the size estimation model of the overall plant,the overall nuclear power plant has been optimized by using the NHABC algorithm,aimed to improve the thermodynamic efficiency and decrease the weight and volume of the overall plant.According to equivalent heat drop theory,a matrix method of calculating the mass flow of each extraction steam was given.Then,the thermodynamic efficiency of the nuclear power plant can be computed.The size estimation model includes the mathematical models of the units developed in the present work,i.e.,feedwater heaters,moisture separator reheater,reactor coolant pump.Other mathematical models of major units which have been developed are also included,i.e.,reactor core,steam generator,pressurizer,reactor coolant pipeline,reactor pressure vessel,condenser and turbine.The coupling relationship between the units was considered.In the multi-objective optimized results,the thermodynamic efficiency increases almost 1.8%,the weight and volume decrease 2.3% and 6.0%,respectively.