UPGRADING INSTRUMENTATION CONTROL-SYSTEMS FOR PLANT SAFETY AND OPERATION

Upgrading the electrical systems and instrumentation and control syste ms has become increasingly more important in the past few years for nu clear power plants currently in operation. As the requirements to be m et in terms of plant safety and availability have become more stringen t in the past few years. Western plants built in the sixties and seven ties have been the subject of manifold backfitting and upgrading measu res in the past. In the meantime, however, various nuclear power plant s are facing much more thorough upgrading phases because of the diffic ulties in obtaining spare parts for older equipment systems. As digita l technology has become widespread in many areas because of its advant ages, and as applications are continuously expanding, conventional equ ipment and systems are losing more and more ground as a consequence of decreasing demand. Merely because of the pronounced decline in demand for conventional electronic components it is possible for equipment m anufacturers to guarantee spare parts deliveries for older systems onl y for specific future periods of time. In addition, one-off manufactur e entails high costs in purchases of spare parts. As a consequence of current thinking more and more focusing on availability and economy, u pgrading of electrical systems and instrumentation and control systems is becoming a more and more topical question, for older plants even t o ensure completion of full service life.