Secondary Side Condition Monitoring and Operational Assessment (SS-CMOA)

The Westinghouse Solution

Designed as a diagnostic planning tool, Westinghouse’s Secondary Side Condition Monitoring and Operational Assessment (SS-CMOA) is a living document that evaluates the secondary side of the steam generator (SG) and interfacing systems. Various secondary side inputs are evaluated in the SS-CMOA over the life of the SG, including, but not limited to:

  • SG design and materials of construction
  • SG chemistry, SG deposit history
  • Thermal performance
  • SG maintenance parameters

This tool assists in developing long-term strategies that align SG operation and performance with utility-specific goals.


The SS-CMOA provides technical justification for SG services in accordance with a utility’s SG asset management program. It is recommended to perform the SS-CMOA following completion of SG maintenance activities in a refueling outage. The SS-CMOA performs the following functions:

  • Supports decisions made by the SG management team
  • Evaluates multiple maintenance and operating scenarios for optimized long-term planning
  • Plans for strategic chemical cleanings applying EPRI methodology
  • Highlights strengths in secondary side programs and identifies areas for improvement
  • Satisfies Chapter 10 of the Electric Power Research Institute (EPRI) Steam Generator Integrity Guidelines, which specifies the requirement to include measures to maintain the SG secondary side integrity in a utility’s SG program
  • Provides diagnostic feedback for evaluating abnormal operating conditions and changes in maintenance scope
  • Provides a comprehensive history of secondary side chemistry and SG performance

Customer Benefits

The SS-CMOA can provide the following benefits to utilities:

  • Supports cost savings initiatives by technically justifying, where appropriate, reduction or elimination of SG inspections, advanced SG cleaning, and other SG maintenance services
  • Provides technical data for utility personnel to share with management to support operational and maintenance decisions
  • Serves as a convenient reference in Degradation Assessments as well as tube integrity Condition Monitoring and Operational Assessments
  • Evaluates impacts of secondary side water chemistry, SG maintenance and other operational changes
  • Acts as a supporting document during Institute of Nuclear Power Operations (INPO) audits and internal self-assessments


The SS-CMOA is provided as a report to the utility which contains:

  • An evaluation of the secondary side operating parameters through the current cycle
  • Performance expectations through subsequent cycles
  • Ten cycles of SG maintenance recommendations (see table example below)


Over a dozen plants have utilized the SS-CMOA to support their long-term SG operations. Several customers perform the SS-CMOA every time SG outage maintenance scope is completed.


Rachel DeVito, PE