Core Spray Pipe Repair & Replacement
Core Spray Pipe Repair
BWR plants have reported core spray pipe cracking for over 25 years. That’s why AREVA has invested to deliver proven, comprehensive solutions for emergent flaws in core spray pipe welds. Our repair techniques allow for repair of most weld locations in a timely manner to ensure continued operation for the life of your plant.
AREVA utilizes mechanically-engaged clamps on the core spray pipe to replace the function of the flawed welds by transmitting the piping loads that exist at each joint. These clamps provide a mechanical load path and restrict the pipe joints from opening at each flawed weld – minimizing the leakage of core spray flow while structurally replacing the flawed welds.
Features & Benefits
- Repair meets the BWRVIP-19A design criteria
- All materials meet the BWRVIP-84 guideline
- All welds may be repaired within allowable leakage range
- Less invasive than replacement
- Restores the safety function of the core spray pipe to deliver emergency core-cooling water flow
- Electrical Discharge Machining during installation avoids FME issues
- A simple design replaces the suspect weld
Core Spray Pipe Replacement
AREVA can provide a full core spray pipe replacement utilizing mechanical attachment features between the inlet nozzle and the core shroud. Designed for remote underwater installation, new piping attaches between the nozzle safe-end and core spray sparger. No welding is required for the attachment of the replacement piping.
The proposed core spray piping partial and complete replacement design and installation approaches meet all BWRVIP and nuclear repair/replacement requirements while offering several important features:
- No welding to service-sensitive stainless steel reactor components and no in-vessel welding. The number of shop welds utilized in the replacement design is minimized, and all are fully solution-annealed and IGSCC-resistant. No crevices are permitted at weld locations.
- All IGSCC-susceptible welds in the core spray piping between the core shroud and reactor vessel nozzles are eliminated in the complete replacement. The partial replacement would eliminate susceptible welds from above the field weld coupling to the core spray sparger.
- The mechanical joints in the core spray piping and the attachments to the shroud and core spray nozzle safe end provide adjustability, allowing for a wide range of as-built dimensional variations and provisions that lock them at installation and assure vibration-resistant joints similar to the existing installation.
- The core spray piping hydraulic design will minimize the flow resistance such that core spray delivery will meet current minimum flow requirements.
- In-vessel cutting will utilize proven, qualified tooling and processes.
- The design will be installed remotely from the refuel floor.
Features & Benefits
- No welding to service-sensitive stainless steel reactor components and no in-vessel welding
- Eliminates all IGSCC-susceptible welds in the core spray piping between the core shroud and reactor vessel nozzles
- Adjustable mechanical joints allow a wide range of as-built dimensional variations
- Hydraulic design minimizes flow resistance, enabling core spray delivery to meet current minimum flow requirements
- AREVA can install the design remotely from the refuel floor