Licensing issues associated with the use of computers in the nuclear industry

Computers are increasingly important to ensuring the safety of nuclear power stations. They have been proposed or introduced into operator information systems, operational control systems, as well as into systems for core protection and plant protection. Although the developments in the individual countries are not at the same pace, they do tend to render similar results. Particular licensing problems arise because of the increasing complexity of computer systems and the software involved. In the past licensing has been closely connected with the mental understanding of the systems to be licensed. This understanding is endangered with greater complexity of the systems. Although several ''manual'' methods of licensing exist, the problem of cost effective licensing is still more or less unsolved. For the future it is expected that tools will reduce the licensing efforts leaving the licenser and assessor free to concentrate on the most important issues. Such tools will probably make use of artificial intelligence techniques. They will enable the inclusion of more complex functions into safety systems and thereby increase the number of safety criteria and the number of echelons od defense. Another important use of artificial intelligence techniques will be the area of operator information systems and maintenance, including computer hardware maintenance. They will provide early detection of problems in the plant and thereby largely enhance plant availability and safety. Further studies are being proposed in the fields of software licensing tools, artificial intelligence, fail-safe and fault-tolerant software architectures, test procedures and system specification