Advanced Diagnostics for the Control Element Drive Mechanism System in Pressurized Water Reactors

A light water reactor is equipped with control and shutdown rods which are inserted into and withdrawn from the reactor core to control reactivity. The positioning of the control and shutdown rods is performed in Combustion Engineering designed plants with the control element drive mechanism system, which includes a number of subsystems and components critical to safe and reliable plant operation. Aging and obsolescence issues have resulted in failures and plant downtimes that could have been prevented or mitigated by monitoring the condition of system components. The complex design of the control element drive mechanism system inherently creates a need for an on-line diagnostics system that can improve system health monitoring, troubleshooting, and trending capabilities. This proposal offers to benefit the plants through increased system reliability, reduced plant downtime, and improved troubleshooting capabilities. The Phase I project established the feasibility of continuous on-line health monitoring, advanced fault detection, and diagnostic techniques for the control element drive mechanism system. This provides a non-intrusive solution using existing plant signals for detecting component failures and degradation. The Phase I effort resulted in many techniques and applications which will provide significant benefits to this aging system. In Phase II, a research and development effort will prototype a comprehensive health monitoring and diagnostic solution for the control element drive mechanism system. This prototype system will integrate automated data collection with the monitoring, fault detection and diagnostic techniques developed in the Phase I effort. This system will be designed, developed, validated, and demonstrated in the proposing firms laboratory and at participating nuclear power plant facilities. Commercial Applications and Other Benefits: This Phase II effort will result in three commercial product designs including a portable field test system, a permanently installed comprehensive system, and field testing services to evaluate the control element drive mechanism system using the techniques and tools developed under this project. These products are currently applicable to nearly 40 existing and planned future power plants.