Reactor protection system is one of the most important safety systems in nuclear power plant and shall be designed with very high reliability. Digital computer-based Reactor Protection System (RPS) takes great advantages over its conventional counterpart based on analog technique and faces the issues how to effectively demonstrate and confirm the completeness and correctness of the software that performs reactor safety functions in the same time. It is commonly accepted that the essential way to solve safety software issues in a digital RPS is to pass a strict and independent Verification and Validation (V&V) process, in which integrated RPS testing play an important role to form a part of the overall system validation. Integrated RPS testing must be carried out rigorously before the system is delivered to nuclear power plant. The integrated testing are often combined with the factory acceptance test (FAT) to form a single testing activity, during which the RPS is excited by emulated static and dynamic input signals. The integration testing should simulate normal operation, anticipated operational occurrences and accident conditions, as well as anticipated faults on the inputs to the DRPS such as sensors out of range or ambiguous input readings. All safety function requirements of digital RPS should be confirmed by representative testing. The design and development of a test facility to carry out the integrated RPS testing are covered in this paper, which is merged in the research on a digital RPS engineering prototype for a nuclear power plant. The test facility is based on PXI platform and LabVIEW software development environment and its architecture design also takes into account the test functions future extensions such as hardware upgrades and software modules enhancement. The test facility provides the digital RPS with redundant, synchronized and multi-channel emulated signals that are produced to emulate all protection signals from 1E class sensors and transmitters with time varied value within their possible ranges, which would put integrated RPS testing into practice to confirm the digital RPS has fully met its predefined safety functionality requirements. The designed test facility can provide an independent verification and validation process for the research of digital RPS with scientific methods and authentic data to evaluate the RPS performance thoroughly and effectively, such as measuring threshold precision and trip response time, analyzing system statistical reliability and so on.
Dynamic Modeling of Reactor Protection System in Nuclear Power Plant for Reliability Evaluation Based on State Transition Diagram
