Direct replacement success story:
Hope Creek Generating Station
Location: Lower Alloways Creek, New Jersey
The ongoing maintenance needs of power generation plants can pose a dilemma for facilities management personnel, and that’s especially true at nuclear plants. In 2002, Hope Creek Generating Station had concerns about its aging low-voltage circuit breakers — which had been in use since the facility opened in 1986.
After carefully evaluating all options, including whether to refurbish the existing breakers, the station opted to replace all existing low-voltage breakers. Hope Creek facilities management selected a Square D Masterpact NW direct replacement breaker designed by Schneider Electric Services and offered by Nuclear Logistics Inc. The project got underway in 2005 with a scope of replacing more than 260 legacy circuit breakers.
Application
Hope Creek’s electrical output is capable of supplying 1.017 million homes and, in fact, produces roughly half of the electricity used in New Jersey.
The facility has two types of circuit breakers:
• Non-safety related: These circuit breakers operate equipment that is not essential to the plant’s operation (lighting, air conditioning, etc.).
• Safety-related: Unique to nuclear plants, these circuit breakers are relied upon to properly operate mission-critical equipment, such as cooling water pumps and the power equipment required to safely shut down the plant if a critical event occurs.
“The ongoing maintenance of the equipment, coupled with the license extension, pointed Hope Creek into the direction of replacement. There were just a lot of long-term benefits with replacing the circuit breakers.” — Dave Davis, Northeast Region Site Manager, Nuclear Logistics
Solution
Nuclear Logistics and Schneider Electric Services collaborated to supply a low-voltage replacement circuit breaker, which included a custom adapter cradle that allowed the new circuit breaker to be installed into the existing cubicle without any modification. All the replacement work was done by in-house electricians who were trained by Schneider Electric Services and Nuclear Logistics.
The entire project required a lot of planning and coordination. Because certain circuit breakers can only come out of service during a refueling period, and the presence of redundant equipment, which can require shutting down sister units, the installation schedule called for having a sound strategy.
Results
Benefits of the replacement circuit breakers have already been evident says Greg Lichty, Plant Component Specialist for Circuit Breakers and Motors. The new breakers are virtually maintenance-free — only routine testing and inspection are required. Plus, the project is putting in place a common circuit breaker throughout the facility, creating time and cost savings for installation and future maintenance, because plant electricians don’t have to be trained on multiple types of circuit breakers, while reducing inventory requirements for spare parts. The adapter cradle installed to ensure the new circuit breakers mate perfectly with existing switchgear has a shutter system that prevents exposure to a live bus, thus increasing safety for plant electricians.
In addition, the new circuit breakers are lubricated with synthetic grease, which reduces the chances of grease hardening. Grease hardening is one of the most common sources of circuit breaker failure in the nuclear industry.
“We have a more reliable breaker,” says Lichty. “Minimal maintenance is required and, in the case of corrective maintenance, you can replace any part on the breaker with a Phillips screwdriver or Allen wrench. Plus, there is a better allocation of human resources. Plant electricians can be doing other things rather than working on circuit breakers.”
The presence of Micrologic™ digital trip units on the AC replacement circuit breakers provide more intelligence to facilities management, everything from monitoring the load coming through a given circuit breaker to chronicling its trip history. They can even be used for power monitoring.
Finally, while completion of a circuit breaker replacement project was not a requirement for the license renewal process, facilities management understood that adding another 20 years to a 40-year license would require eventual action.
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