Verification and validation of the Reactor Protection System at the Paks Nuclear Power Plant

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Dr. Vajk István
Department of Automation and Applied Informatics

This master’s thesis presents the verification and validation process of the Reactor Protection System, the main primary circuit safety instrumentation and control system of the Paks Nuclear Power Plant. The thesis also considers the possibilities of extending the existing testing practices. The re-evaluation of the verification and validation process is required because the system software forming the basis of the Reactor Protection System is planned to be updated. Verification is the process of checking whether the result of a task done as part of the upgrade meets the requirements of that particular task. Validation is the process of checking whether the upgraded system meets its specification.

The thesis introduces the current and previous versions of the Reactor Protection System and the design basis considered during its development, especially regarding the fundamental requirements of nuclear safety and their manifestations in the system’s architecture. The hardware and software platform and development environment of Teleperm XS, the nuclear I&C platform that the Reactor Protection System is based on, is also presented. Furthermore, ProfiSim, the environment used as the formal unified specification and simulation system for the system, is demonstrated in the thesis.

To facilitate the better understanding of the verification and validation process, the thesis describes the different testing environments that have varied capabilities and are used for diverse goals. The unified language of test case definitions and the tools provided to convert them automatically to the different testing environments, avoiding the possibility of human error, are shown in detail. In order to evaluate the completeness of the existing testing methods, the thesis examines the possibility of developing unit tests for the software building blocks in the ProfiSim environment. The developed unit tests serve as an example to show the methods that can be successfully used to develop such test. The methods are based on the principles described in previous works related to software testing. These examples further assure the safety of the system, while also pointing out ways to increase the test coverage.


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