Development,Verification And Validation Of An FPGA-based CPR1000 PWR Protection Sub-system

The existing nuclear safety instrumentation and control(I&C)systems mainly adopt microprocessor-based technical solutions.Although the field programmable gate array(FPGA)technology has many advantages compared with microprocessor-based solutions,it has not yet been widely used.Some technical standards and guidelines have been issued to guide the development,verification and validation(V&V)of FPGA-based nuclear I&C systems,but currently there is still no universally accepted standards or regulatory guidelines in the nuclear power industry.To achieve high credibility and ensure the reliability of FPGA-based safety I&C,the operational standards,the life cycle process facilitating development,and the V&V systems meeting the licensing requirements are required.In order to research the V&V activities and implementation methods in different development phases of the safety FPGA-based I&C system,the reactor protection system of CPR1000 is chosen as the research object in this paper.Combining with the existing international standards,the development life cycle and V&V procedure of FPGA-based I&C system in NPPs is presented in this paper.According to this methodology,three FPGA-based CPR1000 reactor protection channels(Over-temperature △T protection,Over-power △T protection and primary loop coolant flow low protection)are developed.V&V works are carried out in all phases of the development life cycle.The test technologies with good operability and credibility are utilized to ensure the correctness and integrity of the test results of different V&V activities.In the implementation phase,an UVM-based(Universal Virification Methodology)test platform and third-party simulation tools are applied to ensure 100%code coverage and functional coverage of software components and integration tests.A Lab View-based test platform is developed for system integration in the system integration phase.In the acceptance phase,system acceptance tests are carried out on a CPR1000 NPP operation principle simulator and Lab View-based test-platform.Three conclusions are achieved:firstly,taking into account the hardware and software characteristics of FPGA,the existing software V&V methods can be applied for the V&V activities of FPGA-based NPP I&C systems;secondly,using UVM and third-party simulation tools,the bugs in the RTL model can be found effectively,and the 100%test coverage can be reached finally;thirdly,applying the CPR1000 reactor operation principle simulator in system acceptance test,system design errors and defects can be discovered accurately,intuitively and efficiently,which provide strong and credible evidence for V&V and licensing.The results of this paper could provide a theoretical and technical reference for the development,V&V and licensing of FPGA-based NPP DI&C systems.