The PWR Protection System - Present and Future

In a nuclear power generating station, the system used to protect the reactor and its containment is the plant protection sytem. The pressurized-water-reactor (PWR) protection systems encompass all electrical and mechanical devices and circuitry (from sensors to actuated device input terminals) involved in generating those signals associated with the protective function. These signals include actuation signals for the Reactor Protection System (RPS) and Engineered Safety Features System (ESFS) such as Safety Injection Actuation System, Containment Spray Actuation System, Main Steam Isolation System, Auxiliary Feedwater Actuation System, and Recirculation Actuation System. This paper deals with the present status and future development of the Plant Protection Systems utilized by Combustion Engineering, Inc. (C-E) and Kraftwerk Union (KWU) for their Pressurized Water Reactors. The latest techniques of signal processing, logic design, reactor trip and engineered safety features actuation circuitry, automatic testing, isolation and interfacing, are discussed. Current system design criteria, which as a result of the dynamic national and international licensing atmospheres influence system design philosophies, are highlighted.