September-October 2018 NPJ

Nuclear Plant Journal, September-October 2018 NuclearPlantJournal.com 43 Charles Fox Charles Fox, Engineer Sr., has worked at Palo Verde Generating Station for nine years. As a system engineer, he focuses on site Control Systems, Instrumentation and Control (I&C), Control Element Drive Mechanism Control System (CEDMCS), and Failure Analysis. Charlie earned a Bachelor of Science in Electrical & Computer Engineering from the University of Minnesota-Duluth and is a Professional Engineer-Controls. minimum at 392°F. In a 2010 thermal aging test, a Westinghouse coil was placed in an oven at 555°F for 120 days. The physical and electrical characteristics of the coil were not affected by this exposure. In the Westinghouse coil, dual layers of thin fiberglass filaments are wound around the solid copper wire in opposing direction creating a fiberglass insulated wire. This insulated wire is then coiled onto a fiberglass bobbin to form the final coil winding. A silicone impregnating resin is then used to impregnate the windings to hold the wires together and provide better heat transfer. Since the fiberglass filaments provide a very high degree of electrical insulation, the silicone resin only provides a heat transfer function and very little is used. The wire insulation fiberglass material is rated for over 1200°F and remains intact at even much higher temperatures. This essentially eliminates formation of a potential electrical short between coil windings. The Westinghouse HT CEDM Coil successfully passed a new thermal aging test and is now rated for 500°F for 60 years. AWestinghouse brochure provides more information and photographs of the HT CEDM coil. The Westing- house HT CEDM Coil demonstrates innovation by com- bining old and new ideas to offer a dras- tic improvement in the performance of the CEDM coils. The pre-existing Westinghouse coil offered an extensive history of success- ful operating experi- ence. Westinghouse capitalized off of the existing design and incorporated it into a form and function that benefits the fleet of CE System 80 nuclear plants. They managed to improve the design, manufacture process, and testing as well. The HT CEDM coil offers an increase to rated temperature, rated life, a potential to decrease the operating temperature, and all while maintaining the electrical characteristics of the coil necessary for proper operation. These benefits offer an increase to operating margin and equipment reliability – precious commodities to the nuclear industry. Safety The coils under discussion are a fundamental piece of equipment to the Control Element Drive Mechanism Control System (CEDMCS). CEDMCS plays a crucial role in reactivity management, a key safety factor and direct contributor to nuclear safety. The improvement to the coil’s operating margin and ultimately equipment reliability enhances nuclear safety. Use of the Westinghouse HT CEDM Gripper Coil will reduce unplanned outages due to original coil failure and thus reduce man-rem exposure and possible accidents during unplanned coil replacement activities. Cost-Savings Impact The increase in rated temperature and life affords the utility an additional 30 years of rated life. The effective cost when From Left to Right: Westinghouse Principal Engineers Bill Struzenski and Greg Falvo; Senior vice President, Site Operations Palo Verde Jack Cadogan, Palo Verde Engineer Sr. Josh Gates, Pinnacle West Board Member Michael Gallagher, and APS President and CEO Don Brandt at NEI’s Nuclear Energy Assembly in Atlanta, GA in May 2018. (Continued on page 44)