SIGMA™ Long-life Reactor Coolant Pump Shaft Seal

October 26, 2021 by Westinghouse Electric Company

Continued design enhancements may cut maintenance costs by as much as 50 percent.

Operational instabilities, susceptibility to variables or even extending service life to better align with other reactor coolant pump (RCP) maintenance activities are all factors that negatively impact a plant’s O&M costs and productivity. While legacy RCP seals have been robust, advancements to the technology are needed to drive increased reliability and profitability.

Westinghouse has developed the new SIGMA™ Long-life RCP Shaft Seal to meet the needs of reliability-focused operators in an ever more challenging commercial nuclear market. The SIGMA seal has been created as a drop-in RCP shaft seal replacement for all three seal stages that requires no RCP or plant modifications to adopt and is fully compatible with the Westinghouse SHIELD® passive shutdown seal. With its improved tolerance to environmental and operating environments, the seal is qualified for up to 12 years of operation. The increased life and reduced maintenance frequencies may be expected to cut seal maintenance costs by as much as 50 percent.

The SIGMA number 1 seal has been designed, tested and piloted in an operating plant, where it was then removed during a planned outage to identify additional performance enhancements. As a result of these thorough inspections, SIGMA number 1 seal is now undergoing an enhanced design phase, focusing on increasing the tolerance of the seal to certain plant conditions and improving the seal’s overall stability of operation.

With the extensive testing, real-life pilot program, and design enhancement phase, the SIGMA seal is poised to provide long-term reliability and reduced O&M costs for operators looking for every edge to drive sustainable and profitable long-term operations (LTO). The full set of SIGMA seals will be available for installation beginning in 2022.

Key Benefits

  • Increased service life – qualified for up to 12 years of operation
  • Improved tolerance to environmental factors and plant conditions
    • Improved start-up performance
    • Reduction in sensitivity, driving stable and predictable performance

Learn More About our SIGMA RCP Seals