Instrument setpoints balancing safety and operating flexibility

The authors summarize analytical strategies used by GE Nuclear Energy in achieving a balance between the primary safety function of a particular instrument setpoint and the need for operating flexibility to avoid undesirable challenges to other plant protection systems. Examples are considered which are typical of the situation with many setpoints and limits commonly contained in reactor technical specifications. Very often, when instrument systems are modified or setpoints reevaluated, a primary objective in the change process is to avoid a need to change the setting specified in the technical specifications. Avoiding technical specification changes is important because it avoids the significant paperwork impact on plant operations and improves operations by minimizing the burden on operators who must be familiar with technical specification requirements. The ability to accommodate major changes in instrumentation and setpoint related information and maintain a high degree of safety without necessitating technical specification changes is very important to flexibility in plant operations