Design And Application Of Nuclear Safety DCS Qualification Scheme

Nuclear-grade Distributed Control System(DCS)is an important computer-based security system,which plays a vital role in the safe and stable operation of the Nuclear Power Plant.According to the requirements of relevant nuclear safety standardsand regulations,nuclear-grade DCS system needs to perform equipment qualification before engineering application.The purpose of equipment qualification is to verify that safety-grade DCS system meets the design requirements,ensure that it can carry out its predetermined functions and performance under the specified operating conditionsand environmental conditions,and meets the relevant requirements of nuclear safety regulations and standards for nuclear safety-grade product qualification.Methods of equipment qualification includes type test method,operation experience method,analysis method or a combination of these methods.At present,the domestic equipment qualification system is not complete and still in the exploratory stage.Domestic design institute and DCS vendors only have some experience in type test methods,other methods lack specific guidance in the relevant standards,and there is no demostic application case.Due to the lack of understanding of the qualification mechanism of nuclear-grade equipment,all tests need to be carried out strictly according to the highest requirements in the standard,which results in high cost and long time of appraisal,and greatly reduces the economy of domestic nuclear-grade equipment.With the development and industrialization of domestic nuclear DCS system,Our country urgently need to study and master the technical mechanism of nuclear-gradeequipment qualification.The qualification requirements are identified in the requirement stage of nuclear grade DCS system and realized in the design stage of computer system.On the basis of meeting the requirements of relevant standards and regulations,the combination of equipment qualification methods is applied in the system validation stage to improve the identification efficiency and save the identification cost.In this thesis,the key points of qualification technology are extracted through studying the relevant qualification standards and periodical documents of nuclear power plant from both demestic and abroad and combining the requirements and the existing design and manufacturing experience of nuclear safety grade products,and the combined qualification method of analysis method and supplementary type test method propose for the first time for domestic nuclear-grade DCS system.The qualification strategy is put forward and analyzed from six aspects: quality assurance process,qualificationstandards,function and performance,test conditions,product type and hardware configuration,and a set of nuclear grade DCS system identification automatic analysis software is designed to automatically generate analysis conclusions.If the analysis is not sufficient to prove that the equipment meets the qualification requirements,type tests shall be carried out in the following order :benchmark tests,environmental tests,EMC tests,seismic tests and isolation tests.The effective application of the combination method will improve the qualification efficiency,save the test cost,and provide a application case for the subsequent domestic nuclear safety grade equipment qualification.In addition,this thesis takes the nuclear DCS system of Fangchenggang Unit3-4 as an application example to apply the combined qualification scheme of analysis method and supplementary type test method.It has been proved by practice that the scheme quickly and effectively verifies that the nuclear DCS system meets the design requirements,obtains good application effect,and successfully passes the strict examination of the national nuclear safety supervision organization and the nuclear power plant owner,thus providing a new idea for the equipment qualification of nuclear DCS system.This scheme can be applied and popularized in the subsequent nuclear grade DCS system supply projects of HRP1000,M310,AP1000,EPR1000,CAP1400 and other reactor types.