Model-based Research On Evaluation And Optimization Of Nuclear Power System

In recent years,the research and development of a variety of new nuclear power platforms such as floating nuclear power platforms,deep-sea nuclear submarines,and land-based mobile nuclear power sources has sprung up around the world,spawning the birth of a large number of new nuclear power concepts.There is no previous general experience for the design of the abovementioned nuclear power systems in the new application scenarios.Therefore,there is an urgent need for performance evaluation and optimization of the design to verify whether it could meet the technical requirements and operation demand of the new applications.Traditional evaluation work often takes documents and drawings as input,and most of the subsystems,majors,and designs are carried out independently.The independent design without effective closed-loop feedback and iterative optimization will easily leads to deviations between design and practical requirements.Therefore,it is necessary to evaluate and optimize the new floating nuclear power platform based on advanced systems engineering methods,to realize the scientific,systematic and precise evaluation and optimization.In this thesis,a model-based system engineering(MBSE)method has been proposed to evaluate and optimize the nuclear power system and the evaluation target is floating nuclear power platform.Environmental adaptability and mobility are used as indicators to establish a MBSE nuclear power system evaluation and optimization platform,realizing the partial engineering application of the MBSE concept in the field of nuclear power research and development,thus achieving the integration of nuclear power system demand demonstration and performance analysis.The abovementioned method verifies the rationality and achievability of MBSE,and provides a set of scientific methodologies and application tools for the evaluation and optimization of the environmental adaptability and mobility of the floating nuclear power platform.In order to evaluate the environmental adaptability and mobility of the floating nuclear power platform,in this thesis,IP200 reactor which would be widely used in recent years has been chosen as the research target.According to the demand demonstration process,demand analysis and function decomposition has been conducted.A model-based evaluation index system has been established which provides an evaluation scale for evaluating and optimizing the performance of the floating nuclear power platform.The IP200 integrated reactor physics,thermal hydraulics,control system and other simulation models have been built according to the performance analysis process,and the ocean condition model of inclining,swinging,heaving has been considered.The reactor core thermal-hydraulic and neutronics have been coupled to provide a technical carrier for evaluating and optimizing the performance of the floating nuclear power platform.Relying on the model-based nuclear power system evaluation and optimization platform,this paper realizes the performance analysis and evaluation of the environmental adaptability under rolling,heaving and inclined conditions,and the mobility under forced cycle step load changing condition and forced cycle to natural cycle condition.The realizability of the modelbased nuclear power system evaluation and optimization method is verified through the calculation process,and the technical path of MBSE concept applied to nuclear power system performance evaluation is opened.The evaluation results show that the design of IP200 can meet the environmental adaptability index requirements under rolling,heaving and inclined conditions.Meanwhile,the mobility index requirements of step load condition in forced cycle can also be met.However,the mobility index requirements of transition time under the condition of forced cycle to natural cycle cannot be met,so it is necessary to iteratively optimize the design parameters related to this condition.In this paper,multi population genetic optimization algorithm is used to optimize the combination of operation strategy parameters,to meet the mobility requirements of the transition time from forced cycle to natural cycle.The optimization research verifies the closedloop feedback process of demand demonstration,performance analysis,evaluation and optimization in the model-based nuclear power system evaluation and optimization method.From the implementation effect,the intelligent algorithm has high optimization speed and obvious optimization effect.This paper completes a beneficial attempt to combine the MBSE method with the research and development process of nuclear power system.Based on the methodology proposed in this paper,the requirements demonstration model and performance analysis model suitable for the environmental adaptability and mobility evaluation of nuclear powered offshore floating platform are established.This breaks through the difficult problem of modeling expression of index system and the model coupling of multiple external force fields and multiple physical fields.The calculation process completes the performance evaluation and design optimization of mobility and environmental adaptability of nuclear powered offshore floating platform.This paper realizes the application practice of MBSE method in the field of nuclear power system evaluation and optimization,which can provide reference for broader application expansion in the future.