Upgraded Actuators Keep Going (and Going…) at Exelon Nuclear

Exelon Nuclear, which operates the largest nuclear fleet in the U.S. and the third-largest fleet in the world, insists on maintaining the highest levels of safety and performance in its nuclear power plants. With a corresponding concern for safety and performance, CCI offers the very best in severe service valve solutions.

This common interest prompted several technical personnel from Exelon Nuclear’s Quad Cities, Dresden, and LaSalle County generating stations to attend an actuator upgrade training seminar at CCI’s World Headquarters in Rancho Santa Margarita, California. At this seminar, the visitors received hands-on training for actuator assembly/disassembly and maintenance on specially-built CCI actuators.

The Exelon Nuclear representatives also witnessed CCI’s test lab actuator, which CCI assembled for an extended cycling test upon the request of Quad Cities Generating Station. Testing of this actuator garnered remarkable results, demonstrating that the actuator will function for nearly 8 million continuous cycles without interruption or intervention.

Such amazing results stemmed from CCI’s breakthrough actuator design, which is based on STI technology and features a modified piston design and improved stem bushing. Often, actuator parts rub together, which damages the actuator and causes failure; however, after 7,858,000 cycles, CCI’s test actuator revealed no evidence of rubbing, no signs of wear on the o-rings or other actuator parts, and little or no leakage.

Although nuclear power plants are not generally open to experimentation with new technology, in this case those at Exelon Nuclear trusted CCI’s knowledge and experience enough to want to try this revolutionary actuator technology on several valves in their plants. Quad Cities opted to go with nine CCI heater drain valve actuators to replace their old actuators that were experiencing failure due to excessive cycling and wearing of the ring seals.

Quad Cities’ previous actuators had a piston with a single Buna-N O-ring as a combination guide and seal. The totally re-designed actuator from CCI features a piston that incorporates a Viton O-ring plus two Teflon guide bands and a grease channel to provide continuous lubrication to the cylinder wall. CCI also modified the stem bushing, making it much more rugged to provide greater support and guidance for the actuator shaft. Additionally, the bushing includes two Teflon guide bands and its own lubrication system to keep the actuator shaft lubricated at all times.

With testing that proved customers can expect uninterrupted service of nearly 8 million cycles, this CCI actuator will provide Quad Cities with extended, reliable performance that means considerable savings in time and money for the customer as the time interval between maintenance cycles is considerably increased. The CCI solution also reduces the quantity of spare parts the customer must keep in stock.

Such impressive benefits prompted Exelon Nuclear’s LaSalle and Dresden plants to follow Quad Cities’ lead and invest in several new actuators of the same technology; so far, LaSalle has purchased nine upgrades and Dresden has purchased seven. Quad Cities also plans to buy nine additional upgrades in 2005. With such superior technology installed, these three generating stations can look forward to outstanding safety and performance for a long, long time.

Published in SOLUTIONS Fall 20004