Innovative Method for Installing Pipe Depth Smart Test Stations at Exelon Nuclear Generation Stations to Quantify Corrosion Rates, Evaluate Cathodic Protection Effectiveness, Quantify Corrosion Potentials and Perform Subsurface Soils Analysis to Support Aging Management Plans and Reasonable Assurance Commitments on In-Service Buried and Underground Pipe and Tanks
For several decades ANSI and NACE direct assessment (DA) standards for monitoring cathodic protection and coating quality (SP0502) have been relied upon by pipeline operators and regulators to accurately monitor the impact of corrosion on transmission pipelines. These same standards have been proven far less useful when deployed in nuclear power plant subsurface environments.
In order to meet regulatory and industry commitments the challenge has been to develop a cost effective method to accurately monitor nuclear plants’ buried pipe. The in-scope pipe is comprised of a dense complex of multiple systems in close proximity at depths sometimes exceeding 30-ft. Most nuclear plants have been in service for over 30 years and rely on original buried pipe systems to perform as designed. These systems are manufactured using various metals, which are bonded together to reduce electrical step and touch potential hazards. Each of these factors reduce the confidence factor of DA, but combined they make the procedure even less effective.
Smart Monitoring Test Stations can be installed without excavation at depths of up to forty feet directly into the subject pipeline local environment. This provides access to critical condition and assessment information that was previously unavailable. Smart test stations have been designed with the following components: two Electrical Resistance Probes (ER), two CP coupons and a stationary reference electrode.
This paper will describe the planning and obstacles encountered during the installation, operation and interpretation of data from recent experiences related to the installation of test stations at Exelon Nuclear Generating Stations. We will describe the process from planning to successful completion including:
• Smart Monitoring Test Station features and function
• Value of precise location insertion of probes
• Digitizing plant buried and underground pipe and tanks
• Smart monitoring test station site location selection
• Push probe method to capture soil samples
• Analyzing and interpreting soil samples
• Evaluating potential impacts from groundwater
• Push probe method of installing smart test stations at or near pipe depth
• Monitoring data from test stations
• Application of information to support AMP and NEI commitments