Instrumentation at Connecticut Yankee and Maine Yankee Atomic Power Stations

This paper summarizes the changes made to the instrumentation and control equipment at Connecticut Yankee since plant startup. There have been additional changes made in the design of Maine Yankee´s control system beyond those already made in Connecticut. These fall into two categories: the first is changes to the nuclear steam supplier´s package as a result of what we have learned from experience with our operating plants; the other category includes the additions made to the basic instrumentation for operator ease and improved performance. These changes between Connecticut and Maine Yankee designs are described. Much of the change seen between these two plants can be ascribed to the requirements of the AEC criteria and to the increased size, complexity and cost of the plant. Other changes result from the differing approaches taken by different NSSS vendors. The owner´s viewpoint and experience is important in reviewing proposed instrumentation as well as any other plant feature. The paper shows the variety of features we have felt important to improve upon, based upon our experience.