Regulatory and safety aspects concerning the implementation of modern instrumentation and control systems in German nuclear power plants

Worldwide investigations and first applications have shown technical advantages of using digital Instrumentation and Control (I&C) systems. Currently in the Federal Republic of Germany there are comprehensive research and development programs to introduce digital I&C systems in nuclear power plants for both operational and safety purposes. German nuclear power plants are starting to upgrade their analog I&C systems. Implementation of digital I&C in nuclear power plant safety systems is becoming increasingly important from the regulatory point of view. In the required licensing procedure the developed I&C system must demonstrate fulfillment of the functionality and reliability requirements prescribed by the regulations. For qualification of I&C systems a comprehensive concept is being developed by German expert organizations in cooperation with the manufacturers which takes into account the properties of digital technology. In this context the qualification status as well as a brief description of regulatory aspects of digital I&C implementation are provided. In addition to the technical development, intensive efforts are being made to adapt and extend the regulatory framework to accommodate the safety application of digital I&C systems. Some safety issues regarding the introduction of digital systems to safety I&C and potential approaches towards their solutions are still under discussion.