Pipeline Repairs at Hope Creek Nuclear Generating Station

The Hope Creek nuclear power plant, located in Lower Alloways Creek Township, New Jersey, is a single unit boiling water reactor with a total generating capacity of 1,216 megawatts net. The plant generates enough electricity to power approximately one million homes each day.

Since the late 1990’s, Hope Creek Nuclear Generating Station has been proactively addressing their buried piping through inspection and targeted repairs. By using this approach, Hope Creek was able to evaluate, prioritize and plan the implementation of repairs to its circulating water pipeline during a refueling outage before leakage or structural issues became a serious problem. Seven segments of 144-inch pre-stressed concrete cylinder pipe (PCCP) were identified as distressed and in need of repair or replacement. The seven segments totaled 57 lineal feet of scope area for structural upgrade. The repair scope was selected through a risk-ranking process designed to identify pipe segments that were most at-risk for failure.

The repair approach involved using a carbon fiber repair system engineered to resist all loading conditions. Carbon fiber-reinforced polymer (CFRP) is a lightweight, high-strength material installed internally within pipelines and is comparable to pipe replacement, except with no excavation — all project steps can typically take place using existing access or man ways.

STRUCTURAL’s understanding of the safety and quality protocol in nuclear facilities combined with its pipe rehabilitation experience and dedicated team approach made the company a natural choice for the project.

The carbon fiber material selected for the project was the V-Wrap™ CFRP system supplied by STRUCTURAL TECHNOLOGIES. As a result, the owner was able to execute upgrade of the pipeline segments utilizing materials, installation, QA/QC and warranty though a single source. STRUCTURAL specialty contracting provided turn-key installation and STRUCTURAL TECHNOLOGIES provided products and engineering support.

Repairs Executed

The scope of work included surface preparation, supply of materials, and installation of the V-Wrap™ carbon fiber system for 57 lineal feet of PCCP along with supply of design, materials and installation of customized scaffolding to facilitate the repairs. The installation phase and full cure of the material had to be achieved within the designated construction timeframe in close coordination with other outage work occurring at the plant. The project presented several unique challenges including removal of muck, construction of access through a cooling tower basin, single point of entry to complete all in-pipe activities, construction of two-tiered access within the 144-inch diameter pipeline, changes in elevation and slope conditions within scope area, and removal of a pre-existing carbon fiber system.

STRUCTURAL was able to work through the challenges and complete installation within the allotted timeframe. Surface preparation was completed using sponge-jet abrasive blasting methods, a surface prep method which minimizes the amount of media needed and contributes to worker and environmental safety by lowering dust levels when compared to traditional grit-blasting techniques.

The installation of the V-Wrap™ system took place using a 24-hour day work schedule with a rigorous quality control program in place. Beyond the installation, the curing of the V-Wrap™ system was also closely monitored and the project was closed out with a final walk-through of the pipe with all participants prior to turnover of the pipeline back to the owner.

The Hope Creek project was completed safely and successfully with high owner satisfaction.