Redesigned, robust coils and coil stacks improve plant performance and reliability by surviving higher operating temperatures
The Challenge
A U.S. utility came to Westinghouse due to failures in its Control Element Drive Mechanism (CEDM) upper gripper coils. An examination of the units operating history indicated that the upper gripper coil failure appeared to have been accelerated by excessively high voltage or exposure to temperatures above its design value.
Our Solution
Our team of technical experts re-designed the CEDM upper gripper coil to withstand 500⁰F for 60 years, a significant performance improvement from the original coil design. These heightened performance characteristics provide additional margin to plants and will prevent temperature-related upper gripper coil failures. The high temperature (HT) coil also simplifies the replacement process since it comes installed in a new, drop-in housing.
The Impact
Our redesign reduced the risk of unplanned plant shutdowns and emergent maintenance activities due to gripper failure. Based on new operating experience and continuous improvement activities, we are extending the redesign to upgrade the entire coil stack to ensure long-lasting, problem-free operation.
Key Statistics
- Initial redesign and installation completed in under 12 months
- New coils designed to withstand 500⁰F for 60 years
- HT upper gripper coils have been successfully installed and are operating in 7 units
