MTA-EN-003-R1

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Administrative Items
Date	4/23/21
Functional Area Where Benefits Will Be Realized	Engineering Maintenance
Reference Implementation Guidance	Condition Assessment and Ultrasonic Inspection of Pre-Stressed Concrete Cylinder Pipe (EPRI 3002014443) NEI 2019 TIP Award Submittal 18 (ID: 12300535); Sonic/Ultrasonic Testing of Pre-Stressed Concrete Embedded Cylinder Pipe (PCCP)
Industry SME	EPRI PRR Contact: NuclearPlantMod@epri.com
Previous Implementation	Please contact EPRI for implementation examples and contacts.
Implementation Enablers	N/A
Applicability	All reactor types All geographic regions
Keywords	Pre-stressed concrete embedded cylinder pipe; PCCP; circulating water; service water; sonic; ultrasonic; NDE; UT
Business Case Analysis Cross-Reference	N/A

Description

Nuclear plant cooling water systems (circulating or service water; CW/SW) connect the plant’s condenser to the ultimate heat sink and, depending on plant layout, may consist of miles of piping. The CW/SW piping is typically large‑bore, buried, concrete piping. Inspections of this piping are necessary to assess the CW/SW system condition and prevent forced outages or plant derating due to pipe degradation or failure.

This MTA describes the use of sonic‑ultrasonic (UT) testing for non‑destructive examinations (NDE) of Pre‑Stressed Concrete Embedded Cylinder Pipe (PCCP). The technique has the capability to obtain resonance thickness frequency, compressive wave velocity, and shear wave velocity through an array of four transducers excited by an impact source. Sonic‑ultrasonic testing provides quantitative volumetric data regarding the pipe condition that can be used in finite element analyses to more accurately assess remaining structural margin of degraded pipe spools.

A US nuclear plant evaluated and implemented use of sonic‑ultrasonic testing in lieu of existing NDE methodology. Utilization of sonic‑ultrasonic testing, in combination with standard methods (i.e., visual inspections and bar sounding), provided the plant the ability to properly prioritize and manage implementation as well as reduce overall cost associated with PCCP repairs.

Benefits

Benefits Estimate

Level 3 – Greater than $5 million per year. One example plant saved approximately $131 million in direct pipe repair costs and avoided $90 million in lost generation over a period of five years by prioritizing and managing pipe repairs.

Benefits Description

• Collection of quantitative data regarding concrete conditions that serves as input for finite element analysis and that can be used for monitoring and trending.
• Improved insight into CW/SW system structural health.
• Provides ability to prioritize and manage SW/CW pipe repairs, thereby reducing cost of non‑essential activities.
• Possibility to avoid plant outages or derating due to degraded CW/SW system.

Costs and Schedule

Cost

Level 3 – The costs for PCCP inspections including visual inspections, bar sounding, and sonic‑ultrasonic testing is less than $1 million. Approximate costs are between $200,000 and $300,000, but cost will vary based on scope and extent of inspections.

Schedule

Approximately one year to plan and execute first set of inspections. The need and timing for future inspections is determined based on the specific conditions at the site.

Scope Context

Costs and benefits are based on a two‑unit site with approximately three miles of PCCP piping.

Risks

• Piping needs to be fully drained to perform inspections using sonic‑ultrasonic testing. Draining 100 % of the piping may be difficult. Pipe area covered by water cannot be tested using the sonic‑ultrasonic or traditional inspection methods.
• Depending on pipe surface conditions, cleaning/descaling may be necessary before inspections can be conducted.
• Sonic‑ultrasonic testing has not been applied to inspections of safety‑related piping. However, existing plant procedures for qualification and calibration of NDE equipment and techniques could be used or adapted to ensure sonic‑ultrasonic testing meets applicable quality assurance (QA) requirements.

SWEEP Score

Category	Level	Description
Cost	3	The cost of pipe inspections, including sonic-ultrasonic testing, is less than $1 million.
Savings	3	Savings from managing pipe repair scope exceed $5 million per year.
Payback	3	Based on costs and benefits above, the payback period is less than one year.
Licensing Readiness	3	Use of sonic-ultrasonic methods to inspect CW/SW piping does not affect licensing. Sonic-ultrasonic inspections of safety‑related piping have not been conducted but are not expected to require regulatory changes.
Technology Readiness	3	The technology was successfully used at a US nuclear plant and has been used for inspections of municipal PCCP systems for many years.
Implementation Proficiency	3	The implementation of this technology does not require knowledge of digital technologies.