U.S. Nuclear Energy Industry Innovations That Focus on Aging Management or Long-Term Plant Reliability
A new series of Associated Press reports raising questions about nuclear power plant safety fails to acknowledge actions that the industry takes proactively to improve performance and address aging management and plant reliability issues.
Over just the past four years, more than 20 of the Top Industry Practice awards presented to industry employees during the Nuclear Energy Institute’s annual conference in May have been for innovations that focus on aging management or long-term plant reliability. They are highlighted below.
Tennessee Valley Authority (TVA)
Employees at the Browns Ferry nuclear energy facility in Alabama have been honored with the 2011 B. Ralph Sylvia “Best of the Best” Award for developing a state-of-the-art method to prevent reactor fuel rod defects. Using real-time stress monitoring of the sealed tubes that hold the uranium fuel pellets, a new methodology called XEDOR has proven highly effective.
Five years ago, the industry established a goal to eliminate by the end of 2010 fuel rod defects that could release radionuclides from fuel pellets. Some damage is caused by the interaction between fuel pellets and the metal tube material called cladding. The phenomenon can result in additional costs to utilities, affect plant operation and subject personnel performing repairs to additional radiation exposure.
Working with AREVA, the winning TVA team implemented a new methodology that performs real-time, online stress calculations for every six-inch fuel rod segment in all parts of the reactor core. It is the first method that can calculate how close fuel rods are to cladding damage, thus ensuring fuel integrity performance.
Omaha Public Power District
Team members at Fort Calhoun Station in Nebraska garnered the 2011 Westinghouse Combustion Engineering Design Vendor Award by looking back 10 years to determine the future of critical metal components at their plant.
The Omaha Public Power District team devised a method to accurately track the development of microscopic “stress corrosion” cracking in nozzle welds for large pipes attached to the reactor vessel.
To achieve this technical advance, the team monitored surface changes of the metal over a 10-year period. By comparing the material condition and trending data, the team was able to determine the current status of the material, predict when granular cracking would take place and plan when to replace the components.
The team enhanced nuclear safety by monitoring the assurance of material condition of plant components and detecting flaws, thus lowering the probability of leaks and reducing worker radiation doses thanks to less frequent examinations. To date, their program has reduced expense for unnecessary nozzle replacements by more than $2 million.
Exelon Nuclear at LaSalle County
Employees at the LaSalle County power station in northern Illinois were awarded the 2011 GE Hitachi Nuclear Energy Vendor Award for collaborating with GE Hitachi on the design, construction, testing and installation of a digital Rod Control Management System that more precisely positions control rods and monitors their placement in the reactor.
The new integrated system displays a detailed map of the control rods with a digital touch screen. It has faster scan capabilities and retains information about control rods’ previous position.
The entire system was installed in just five days during a refueling outage at the LaSalle plant and has performed all control-rod manipulations. The system’s enhanced capabilities—including the ability to isolate rods for troubleshooting without affecting other rods—save maintenance resources and increase plant safety and efficiency.
Southern Nuclear Operating Company
The 2011 Westinghouse Design Vendor Award was won by Southern Nuclear Operating Co. employees at the Farley nuclear plant in Alabama for their innovative reactor coolant pump shutdown seals that greatly reduce seal leakage and enhance safety at the plant.
Reactor coolant pump seals are necessary for safe operation of a pressurized water reactor to help prevent reactor coolant loss in severe events.
To combat the possibility of a loss of coolant accident, the winning team developed a first-of-a-kind shutdown seal called the Shield. The Shield is activated by heat and provides a leak-tight seal if cooling for the reactor coolant pump seals is lost. The design causes the seal components to constrict and reduce flow. The shield can be installed easily and does not require additional modifications to the reactor coolant pump.
Exelon Nuclear at Byron
Employees at Byron power station in Illinois won the 2011 Equipment Reliability Process Award for their development of chemical injection during power operation that reduces iron buildup in heat exchanger tubes and helps maintain plant efficiency.
Iron can build up in the heat exchange tubes of the steam generators, reducing the efficiency of the transfer of heat and lowering power output by the plant. Injection of an iron dispersant into the water that goes through the heat exchange tubes slowed iron accumulation in the steam generators. The reduced need for tube cleanings lowers the radiation dose to workers who clean sludge deposits from the component.
Employees at the Oconee power plant in South Carolina earned one of two 2011 Maintenance Process Awards for improving automatic oilers for a large amount of rotating mechanical equipment.
Duke Energy developed a laser-guided handheld tool that is small, easy-to-use and inexpensive. The laser-guided tool ensures accuracy by generating a bright red line, which is projected onto the bearing housing to serve as a visual reference. Its ease of use means that the time required to check oil levels has dropped to about 30 seconds from five to 10 minutes.
Setting or checking oil levels with the new tool improves the reliability of rotating equipment. With millions of automatic oilers around the world in all industries, this new method is widely adaptable at nuclear energy facilities and other industries.
American Electric Power
Employees of American Electric Power at the Donald C. Cook Nuclear Plant in Michigan won the 2011 Plant Support Process Award for its comprehensive groundwater protection modeling software to maintain safety and enhance public confidence.
To enhance communications when there is leakage of tritium or other materials at plant sites, the winning team pioneered the use of comprehensive groundwater protection monitoring software. The software can display 3D modeling of the site’s systems, structures and components in relation to tritium leakage. The highly interactive software allows for vast amounts of information to be efficiently managed and easily interpreted. Most significant are its predictive and investigative abilities, which can identify the potential sources of a leak and the potential impacts it may have—information that can result in better public and environmental protection.
Employees at the Palisades nuclear power station in western Michigan have been honored with the 2010 B. Ralph Sylvia Best of the Best Award for developing an innovative device that improves the quality of reactor vessel head inspections.
The device, called a gimbaled head, uses ultrasonic transducers to identify irregularities within the welded steel reactor vessel head nozzles used for control rod drive mechanisms and nuclear instrumentation. A vessel head is a massive, multi-ton component that helps house the uranium fuel assemblies that are the energy source for 20 percent of U.S. electricity supplies, as well as various instruments used to operate the reactor.
Previously, engineers at the Palisades plant needed four different kinds of testing devices to complete the inspection. The gimbaled head device performs the entire inspection, conducting an even more thorough, accurate and effective examination in less time. Additional improvements have enabled the ultrasonic transducers to produce higher quality and more consistent inspection information.
Employees at Virginia’s Surry power station collaborated with AREVA to win the 2010 AREVA Vendor Award for developing the Deposit Minimization Treatment process to decrease the buildup of sludge on the plant’s steam generator tubes.
Sludge buildup on the steam-producing side of the steam generator tubes had reduced steam pressure and could have affected power generation. The previous solution for cleaning such material from the tubes required harsh chemicals.
Dominion Engineering and Chemistry personnel developed a cost-effective and environmentally sound solution to eliminate the buildup and restore consistent power generation. The Deposit Minimization Treatment is a safer, simplified system that reduced deposits by 700 to 800 pounds and saved the company approximately $32 million. It does not require harsh chemicals, and waste from the process can be treated with filtration to decompose the active ingredient.
While the old system required that cumbersome equipment be connected to the steam generator in several places, the new system has smaller and fewer pieces and requires only a single connection. The equipment now can be placed in a remote location, eliminating the need for work within the reactor building and enhancing radiation safety and security. The process has application potential for other pressurized water reactors.
FirstEnergy Nuclear Operating Company
Employees at Beta Laboratory landed the 2010 Materials and Services Process Award for their success in upgrading integrated control system circuit cards to increase plant reliabilty. By developing an in-house solution based on manufacturing processes, the team enhanced the design and produced a more reliable circuit card while saving time and money.
Because integrated control system circuit card malfunctions can cause power reductions and other plant challenges, improved equipment reliability was also among the team’s top goals. The new circuit cards featured improved relay design and higher performance specifications, which enhances plant reliability and reduces the preventive maintenance needs of the plant.
All steps of the process were completed in-house including design enhancement, prototyping, manufacturing and assembly. The final step was a rigorous testing process conducted by a comprehensive automated program also developed in-house. The in-house solution upgraded a circuit card for eight percent of the cost of off-site manufacturing. This innovation saved more than $1 million and contributed to greater supply chain efficiency.