NEI 09-14 [Rev 2]

GUIDELINE FOR THE 

MANAGEMENT

OF UNDERGROUND

PIPING AND TANK

INTEGRITY

November 2012

Nuclear Energy Institute, 1776 I Street N. W., Suite 400, Washington D.C. (202.739.8000)

NEI 09-14 [Rev 2]

Nuclear Energy Institute

Guideline for the 

Management of 

Underground Piping and 

Tank Integrity

November 2012

iii

ACKNOWLEDGEMENTS

NEI appreciates the efforts of the members of the NEI Buried Piping Integrity Working Group 

and Task Force, EPRI’s Equipment Reliability Action Plan Committee, and the EPRI Balance of 

Plant Corrosion Integration Committee for their support and direct participation in the 

development of this guideline.

NOTICE

Neither NEI, nor any of its employees, members, supporting organizations, contractors, or 

consultants make any warranty, expressed or implied, or assume any legal responsibility for the 

accuracy or completeness of, or assume any liability for damages resulting from any use of, any 

information apparatus, methods, or process disclosed in this report or that such may not 

infringe privately owned rights.
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REVISION SUMMARY

Revision Description of Changes

0 Initial issue

1 Extensive revision. Most significant changes:

• Included text and intent of the Underground Piping and Tank Integrity Initiative

• Included “shall” statements to designate expectations that must be met or 

deviations from them justified

• Added “Definitions” (Section 4)

• Added an expectation that significant inspection findings and new operating 

experience related to underground piping and tanks be communicated to NEI 

(Section 5.1)

• Expanded the explanation of the intent of the Initiative and included 

clarifications of the Initiative scope (Section 6)

• Expanded guidance for justifying deviations from the Initiative (Section 6.2.6)

• Added Appendix B, a summary of the Initiative requirements in NEI 09-14

2 • Incorporated the response to inquiries received on revision 1

• Added appendix C: Guidance for Inspection Planning 

• Made editorial changes as appropriate
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TABLE OF CONTENTS

1 BACKGROUND.............................................................................................................1

2 INTRODUCTION............................................................................................................3

3 INDUSTRY INITIATIVE ON UNDERGROUND PIPING AND TANK INTEGRITY .............5

3.1 SCOPE ..........................................................................................................................5

3.2 INITIATIVE GOAL............................................................................................................5

3.3 INITIATIVE ACTIONS ......................................................................................................6

3.4 EXPECTATIONS ...............................................................................................................8

3.5 REQUIREMENTS ..............................................................................................................9

4 DEFINITIONS..............................................................................................................10

4.1 ACCESSIBLE ..................................................................................................................10

4.2 ADVERSE INSPECTION FINDINGS .................................................................................10

4.3 BELOW GRADE..............................................................................................................10

4.4 BURIED PIPING .............................................................................................................10

4.5 ENVIRONMENTALLY HAZARDOUS MATERIALS ..........................................................10

4.6 FAILURE........................................................................................................................10

4.7 FLUIDS ........................................................................................................................10

4.8 LICENSED MATERIAL....................................................................................................10

4.9 OUTSIDE OF A BUILDING ..............................................................................................11

4.10 PIPING SEGMENT ..........................................................................................................11

4.11 PRIORITIZATION...........................................................................................................11

4.12 RUN TO FAILURE ..........................................................................................................11

4.13 SAFETY RELATED .........................................................................................................11

4.14 SIGNIFICANT LEAKAGE................................................................................................11

4.15 TANK ........................................................................................................................12

4.16 TUNNEL ........................................................................................................................12

4.17 UNDERGROUND TANK ..................................................................................................12

4.18 UNDERGROUND PIPING ................................................................................................12

4.19 VAULT ........................................................................................................................12

5 INDUSTRY ROLES AND RESPONSIBILITIES ............................................................13
vi

5.1 UTILITIES......................................................................................................................13

5.2 EPRI ........................................................................................................................14

5.3 INPO ........................................................................................................................14

5.4 ANI ........................................................................................................................14

5.5 NEI ........................................................................................................................15

6 INTENT OF THE UNDERGROUND PIPING AND TANKS INTEGRITY INITIATIVE .......16

6.1 UNDERGROUND PIPING AND TANKS INTEGRITY INITIATIVE SCOPE...........................16

6.2 UNDERGROUND PIPING AND TANKS INTEGRITY INITIATIVE IMPLEMENTATION .......17

6.2.1 Procedures and Oversight............................................................................19

6.2.2 Risk Ranking.................................................................................................19

6.2.3 Inspection Plan..............................................................................................20

6.2.4 Plan Implementation ....................................................................................21

6.2.5 Asset Management Plan...............................................................................23

6.2.6 Procedure and oversight ..............................................................................25

6.2.7 Prioritization .................................................................................................26

6.2.8 Condition Assessment Plan..........................................................................27

6.2.9 Plan Implementation ....................................................................................27

6.2.10 Asset Management Plan...............................................................................28

7 REFERENCES.............................................................................................................29

APPENDIX A REPORT TO NSIAC .....................................................................................A-1

APPENDIX B NEI 09-14 REQUIREMENTS .......................................................................B-1

APPENDIX C INDUSTRY GUIDANCE FOR INSPECTION AND CONDITION ASSESSMENT 

OF BURIED AND UNDERGROUND PIPING AND TANKS..........................................C-1
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GUIDELINE FOR THE MANAGEMENT

OF UNDERGROUND PIPING AND TANK INTEGRITY

1 BACKGROUND

This Guideline for the Management of Underground Piping and Tank Integrity describes the 

policy and practices that the industry commits to follow in managing underground piping and 

tanks. The Underground Piping and Tanks Integrity Initiative supersedes the Buried Piping 

Integrity Initiative; it incorporates all of its elements and adds additional scope and milestones.

The Buried Piping Integrity Initiative was approved by NSIAC (Nuclear Strategic Issues 

Advisory Committee) in November 2009. When the Buried Piping Integrity Initiative was 

approved, the scope was limited to piping that was in direct contact with the soil due to the 

inability to directly inspect this piping and due to the potential impact on the environment and 

public confidence if leakage occurred. However additional operating experience has shown that 

piping that is below grade and is not in direct contact with the soil and underground tanks can 

also degrade with potential adverse consequences. As a result, the Underground Piping and 

Tanks Integrity Initiative was developed to incorporate and expand upon the Buried Piping 

Integrity Initiative: its scope also includes selected underground piping that is not in direct 

contact with the soil and specified underground tanks. The key milestone implementation dates 

in the Underground Piping and Tanks Integrity Initiative were established to reflect the added 

initiative scope and its effect on the station resources that will be required to add these items into 

existing programs. The Underground Piping and Tanks Integrity Initiative was approved by 

NSIAC in September 2010. 

Utility implementation of the Initiative will be verified as directed by the NSIAC.

This guideline contains the following information:

• The text and scope of the Underground Piping and Tanks Integrity Initiative (the 

“Initiative”).

• The goals that drive the Initiative.

• Key definitions.

• Roles and responsibilities established to ensure implementation of the Initiative.

• Explanation of the intent of the Initiative.

• Insights for effective and consistent implementation within the industry.

• The content of the report to NSIAC on progress of implementing the Initiative.

The approach to addressing underground piping and tank issues embodied in this Initiative

compliments the expectations in place under the Ground Water Protection Initiative, which was 

approved by NSIAC in 2006 and which remains in effect (guidance on implementation of the 
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Ground Water Protection Initiative is provided in NEI 07-07, Industry Ground Water Protection 

Initiative, Final Guidance Document (Reference 3). The Underground Piping and Tanks 

Integrity Initiative focuses on assessing in-scope components in order to provide reasonable 

assurance of their continued structural and leakage integrity with special emphasis on licensed 

materials. The focus of the Ground Water Protection Initiative (GPI) is on improving the 

management of situations involving inadvertent radiological releases that get into ground water 

and the communications with external stakeholders about those events. Integral to the Ground 

Water Protection Initiative is an evaluation of the potential for unintended leaks of licensed 

materials resulting from work activities and components that contain or could contain licensed 

material, including some components that are within the Underground Piping and Tanks 

Integrity Initiative scoping. In addition, under the GPI, early detection measures are established. 

If licensed material is detected by early detection measures, plant personnel are expected to 

appropriately investigate, remediate and communicate with external stakeholders. Utilities 

should establish governance to ensure that the activities under the two Initiatives are 

communicated and coordinated.
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2 INTRODUCTION 

Underground piping and tanks are used in several applications at plants with different governing 

requirements: 

• safety related pipe and tanks

o governed by plant Technical Specifications and ASME Code, 

• non-safety related pipe and tanks containing licensed material in liquids or gases

o governed by NRC regulations and within the scope of NEI’s Ground Water 

Protection Initiative

• other pipes and tanks in non-safety related systems containing water, fuel oils, gases or 

other media 

o may be governed by local, State and EPA regulations. 

The material condition of underground piping and tanks may not be fully characterized, and one 

of the means of protecting buried components, cathodic protection, may not have been properly

maintained at some stations. In recent years, some self revealing leaks have occurred that could 

impact public confidence, regulatory margin, and, in some cases, plant operation. Additional

impacts that could occur if performance is not improved could be:

• safety and operational challenges

• environmental impacts

• increased regulatory requirements for new and existing plants

• EPA violations with stakeholder or media interest

• license renewal delays

• heightened public opposition to new plant construction

As noted in the executive endorsement of the Underground Piping and Tanks Integrity Initiative, 

the leaders in the nuclear industry recognize that additional industry action directed at assessing 

the condition of underground piping and tanks within the nuclear fleet is warranted. 

Implementation of an assessment program is designed to limit the potential for unintended leaks 

or integrity breaches. The industry’s goal is to proactively address the integrity of underground

piping and tanks and where possible, prevent leakage before it occurs using available 

technologies and other control and evaluative processes. To assure consistent and measured 

progress in this area an NSIAC Initiative addressing underground piping and tank integrity was

approved to commit commercial nuclear power plants to specific program elements. The scope 

of the Underground Piping and Tanks Integrity Initiative includes selected piping and tanks on 

the site that are below grade and outside of buildings. 
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The EPRI Document “Recommendations for an Effective Program to Control the Degradation of 

Buried Pipe” (Reference 1) provides important additional considerations for successful 

implementation of the buried piping aspect of the Initiative. 

NSIAC provides oversight of industry implementation of the Underground Piping and Tanks 

Integrity Initiative. Periodic reports will be prepared for NSIAC addressing:

• Progress on implementation of the elements of this initiative and any deviations.

• Industry experience and lessons learned.

• Progress of technology development.

Specific guidance on the periodic report is included in Appendix A.
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3 INDUSTRY INITIATIVE ON UNDERGROUND PIPING AND TANK 

INTEGRITY 

The Buried Piping Integrity Initiative was approved by NSIAC in November 2009. An 

extension of the Buried Piping Integrity Initiative that addresses selected underground piping and 

tanks was approved in September, 2010. The revised Initiative is known as the Underground

Piping and Tanks Integrity Initiative. 

The expected actions and milestone dates relevant to a given component depend upon whether 

the component was in the original scope of the Buried Piping Integrity Initiative or in the scope 

of the revised and renamed Underground Piping and Tanks Integrity Initiative. The scope, goal, 

and text of the two Initiatives is provided in the following sections.

3.1 SCOPE

The scope of the Underground Piping and Tanks Integrity Initiative includes the following.

A. Those within the scope of the original Buried Piping Integrity Initiative:

• All piping that is below grade and 

o Contains any fluid and

o Is in direct contact with the soil

B. And the following additional components:

• Underground piping and tanks that are outside of a building and below grade (whether or 

not they are in direct contact with the soil) if they

o Are safety related 

- Or -

o Contain licensed material or are known to be contaminated with licensed material.

3.2 INITIATIVE GOAL

The goal of the Underground Piping and Tanks Integrity Initiative is to provide reasonable 

assurance of structural and leakage integrity of in-scope underground piping and tanks with 

special emphasis on piping and tanks that contain licensed materials.

The Underground Piping and Tanks Integrity Initiative will:

• Drive proactive assessment and management of the condition of piping and tanks that fall 

within the Initiative scope.

• Ensure sharing of industry experience.

• Drive technology development to improve available techniques for inspecting and

analyzing underground piping and tanks.
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• Improve regulatory and public confidence in the industry’s management of the material 

condition of its underground tanks and piping systems.

3.3 INITIATIVE ACTIONS

In order to meet these goals, every utility shall implement measures or program(s) to satisfy the 

elements and associated key attributes in Sections 3.3.A and B. The language in Sections 3.3.A 

and B below documents the text of the Underground Piping and Tanks Initiative as approved by 

NSIAC.

A. Original Buried Piping Integrity Initiative Elements

The components governed by the original Buried Piping Integrity Initiative are described in Part 

A of Section 3.1 (Scope). The following elements, attributes, and milestones were established by 

the original Buried Piping Integrity Initiative when it was approved in November 2009. The 

EPRI document “Recommendations for an Effective Program to Control the Degradation of 

Buried Pipe” provides additional details on these elements and attributes. 

Some changes are included in the Initiative description below (as compared to the version 

approved in November 2009) to clarify meaning, but their intent is unchanged and they remain in 

effect under the Underground Piping and Tanks Integrity Initiative. 

1. Procedures and Oversight – By June, 30, 2010:

• Ensure clear roles and responsibilities including senior level accountability for the 

Buried Pipe Integrity Program.

• Develop a Buried Pipe Integrity Program document and implementing 

procedures.

2. Risk Ranking – Risk Rank buried piping segments by December 31, 2010. Risk 

Ranking shall incorporate the following attributes:

• Pipe function

• Pipe locations and layout

• Pipe materials and design

• Health of cathodic protection systems, if applicable

• Based on the above data and other information, determine:

o The likelihood of failure of each piping segment

o The consequences of failure of each piping segment

• A means to update the risk ranking as necessary

• A database to track key program data, inspection results, and trends
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3. Inspection Plan – By June 30, 2011, develop an inspection plan to provide reasonable 

assurance of integrity of buried piping. This plan shall include the following key 

attributes:

• Identification of piping segments to be inspected

• Potential inspection techniques

• Inspection schedule for buried piping segments based on risk ranking

• Assessment of cathodic protection, if applicable

4. Plan Implementation – Implementation of the Inspection Plan shall start no later than 

June 30, 2012. The condition assessment of buried piping containing radioactive material 

shall be completed by June 30, 2013.

5. Asset Management Plan – Inspection results shall be used as input to the development 

of an asset management plan for buried piping. This plan shall receive a high level of 

review and approval and will be in place by December 31, 2013.

B. Underground Piping and Tanks Integrity Initiative Elements

The components falling within the scope of the Underground Piping and Tanks Integrity 

Initiative are described in Part B of Section 3.1 (Scope). The elements, attributes, and milestones 

described below are established for the additional scope of the Underground Piping and Tanks 

Integrity Initiative. 

1. Procedures and Oversight – By December 31, 2011

• Identify the plant programs or measures that manage the material condition of 

components within the scope of the Underground Piping and Tanks Integrity 

Initiative.

• Establish the necessary controls and implementing process to coordinate the 

applicable programs and measures and ensure they meet the intent of the Initiative.

• Establish clear roles and responsibilities including senior level accountability for 

implementation of the Underground Piping and Tanks Integrity Initiative. 

2. Prioritization – Prioritize underground piping and tanks by June 30, 2012. Prioritization 

shall consider the following attributes: 

• Function

• Locations and layout

• Materials and design

• Process fluid 

• Health of cathodic protection systems, if applicable
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• Based on the above data and other information, determine:

o The likelihood of failure of each component 

o The consequences of failure of each component

• A means to update the prioritization scheme as necessary

• Process(es) to allow retrieval of key program data

3. Condition Assessment Plan(s) – By December 31, 2012 develop or identify existing 

condition assessment plans that will provide reasonable assurance of integrity of components 

within the additional scope of the Underground Piping and Tanks Integrity Initiative. These 

plans shall include the following key attributes:

• Identification of underground piping and tanks to be assessed

• Potential assessment techniques 

• Assessment schedules that take into account the relative priority of components. This 

schedule should be coordinated with the schedule developed for the original Buried 

Piping Integrity Initiative to ensure that the components with the highest overall 

priority are addressed first.

• Assessment of cathodic protection, if applicable

4. Plan Implementation – Implementation of the Condition Assessment Plan for underground 

piping and tanks shall start no later than June 30, 2013. The condition assessment of 

underground piping and tanks containing radioactive material shall be completed by June 

30, 2014.

5. Asset Management Plan – Inspection results shall be used as input to the development of 

asset management plans for components within the scope of the Underground Piping and 

Tanks Integrity Initiative. These plans shall receive a high level of review and approval and 

will be in place by December 31, 2014.

3.4 EXPECTATIONS

The expected outcome of the Underground Piping and Tanks Integrity Initiative is improved 

regulatory and public confidence in:

• the Industry’s management of the material condition of its underground tanks and piping 

systems.

• the appropriateness of actions taken to establish reasonable assurance of their structural 

and leakage integrity. 

Significant leaks from underground piping and tanks across the industry will be trended as a 

means of determining the Initiative’s affect on the condition of these components.
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In order to meet the goals of the Initiative, every utility should engage in industry 

activities (such as the Buried Piping Integrity Group) that support implementation of the 

Underground Piping and Tanks Integrity Initiative.

Industry organizations (EPRI, ANI, INPO, and NEI) cooperate in the manner described in this 

guideline and provide the information necessary to prepare periodic updates to NSIAC.

3.5 REQUIREMENTS

Every utility shall ensure that activities associated with the Underground Piping and 

Tanks Integrity Initiative and this document are implemented at its nuclear power plants

in accordance with the intent of the Initiative and the implementation dates specified 

therein. Whenever the word “shall” is used in this document it indicates an action that is 

required under the Underground Piping and Tanks Integrity Initiative. If a plant cannot 

or will not implement any part of the Initiative (Sections 3.3.A and B) or a “shall” 

statement in this document, a justification for deviation from the Initiative shall be 

developed and processed in accordance with Sections 6.2.1 and 6.2.6.

Appendix B captures all the required elements of this document. Users should not rely on this 

appendix alone, but should read the document to ensure that the context of the requirements is 

fully understood.
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4 DEFINITIONS

4.1 ACCESSIBLE

Piping and tanks that can be routinely observed without the required support of special tools or 

other assistance. Activities that would indicate inaccessibility include removal of security 

devices or manways, use of lifting rigs, and performance of excavation, or modification of

building structures, armored embedments or encasements.

4.2 ADVERSE INSPECTION FINDINGS

Results from an inspection that has been determined to require an immediate repair or a repair

within one operating cycle.

4.3 BELOW GRADE

Locations below standard ground elevation as defined at the station.

4.4 BURIED PIPING

Piping that is below grade and in direct contact with the soil.

4.5 ENVIRONMENTALLY HAZARDOUS MATERIALS

Materials that are subject to EPA or EPA-authorized State regulations or that are specifically 

addressed in a plant’s environmental program(s). 

4.6 FAILURE

A breach in the structural or leakage integrity of a piping system or a tank. 

4.7 FLUIDS

Fluids include both liquids and gases (including instrument air). 

4.8 LICENSED MATERIAL

Licensed material (from 10 CFR 20.1003) (or licensed radioactive material as used in this 

document) means source material, special nuclear material, or byproduct material received, 

possessed, used, transferred or disposed of under a general or specific license issued by the 

Commission. Components containing licensed material covered under NEI 09-14 should be 
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consistent with those identified in NEI 07-07 (Reference 3). This definition does not associate a 

specific level of radioactivity with licensed material because it is not possible to do so. A 

determination of what is licensed material in any situation must be made by radiation health 

personnel at each utility – see the discussion under scope for additional clarification.

4.9 OUTSIDE OF A BUILDING

A component is outside of a building if it is beyond the outside surface of all exterior walls and 

floors in the building. 

4.10 PIPING SEGMENT

Portions of buried piping systems that are grouped together for risk ranking purposes based on 

similarities such as installation, manufacture, or environmental conditions. Some risk ranking 

methods may use other terms to refer to piping segments, such as zones.

4.11 PRIORITIZATION

The process of assigning relative importance of scoped components as determined by a set of 

parameters that reflect design and in situ conditions. The intent of the word “prioritization” as 

used in this document is to imply a process that is less formal than risk ranking.

4.12 RUN TO FAILURE

A strategy focused on repairing piping or tanks after leakage is discovered as opposed to 

assessing these items over time with the goal of preventing leakage.

4.13 SAFETY RELATED

Structures, systems, and components that are relied upon to remain functional during and 

following design basis events to ensure the integrity of the reactor coolant pressure boundary, the 

capability to shut down the reactor and maintain it in a safe shutdown condition, or the capability 

to prevent or mitigate the consequences of accidents that could result in potential offsite 

exposure comparable to the guidelines in 10CFR50 section 34(a)(1), 67(b)(2) or 10CFR100.11.

4.14 SIGNIFICANT LEAKAGE

Leaks which meet any of the following criteria

• Result in concentrations that could exceed the regulatory concentrations or limits 

established by the NRC or EPA, or 

• Result in voluntary communication under the industry Ground Water Protection 

Initiative, or 
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• Result in the system or component being out of service

4.15 TANK

A fully enclosed stationary vessel used to hold or store fluids for distribution. Tanks are 

constructed primarily of non-earthen materials (e.g., wood, concrete, steel, or plastic) which 

provide structural support. Tanks do not include basins, ponds or reservoirs.

4.16 TUNNEL

A structure that is outside of a building, below grade, designed to accommodate personnel, and 

not routinely accessible. 

4.17 UNDERGROUND TANK

All tanks that are outside of buildings and sufficiently below grade such that there is a reasonable 

possibility that leakage from inaccessible portions of the tank may not be detected. Detection 

can be accomplished by direct observation or by instrumentation that is capable of reliably 

detecting leakage before it becomes significant (see definition of Significant Leakage). The 

tanks may be in direct contact with concrete or located in trenches, underground vaults or 

tunnels. Within the context of this Initiative, underground tanks include abandoned tanks 

connected to active systems. (Note that the word “underground” has a different meaning when 

used within the context of the Underground Piping and Tanks Integrity Initiative as compared to 

its meaning when used within the NRC’s Generic Aging Lessons Learned report (GALL, NUREG 

1801). Chapter IX of GALL defines underground as below grade and not in direct contact with 

the soil. NEI 09-14 defines underground as including both components that are buried (in direct 

contact with the soil) plus those that are not indirect contact with the soil.)

4.18 UNDERGROUND PIPING

All piping that is below grade, not accessible, and outside of buildings. Buried piping (below 

grade and in direct contact with the soil) is considered to be a subset of underground piping. 

(Note that the word “underground” has a different meaning when used within the context of the 

Underground Piping and Tanks Integrity Initiative as compared to its meaning when used within 

the NRC’s Generic Aging Lessons Learned report (GALL, NUREG 1801). Chapter IX of GALL 

defines underground as below grade and not in direct contact with the soil.)

4.19 VAULT

A structure that is outside of a building, below grade, not designed to accommodate personnel 

and not routinely accessible.
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5 INDUSTRY ROLES AND RESPONSIBILITIES 

This guideline will be implemented through the activities outlined below. These activities have 

the following intended purpose:

• Implementing the Underground Piping and Tanks Integrity Initiative

• Supporting the intent of the Initiative 

• Verifying implementation of the Initiative through maintenance and monitoring of a set 

of metrics described in the report to NSIAC (Appendix A)

• Ensuring that operating experience related to underground piping and tank integrity is 

communicated 

• Continuing research to identify and develop new techniques for inspection and 

maintenance/replacement of buried piping and tanks

5.1 UTILITIES

Utilities shall perform the following actions in support of the Initiative:

• Implement the actions required by the Initiative (Section 3.3 and all “shall” statements in 

this document).

• Process a justification for deviation (Section 6.2.6) whenever an action required by the 

Initiative or a “shall” statement in this document cannot be met.

• Report all results from inspections performed in accordance with the Initiative in the 

manner proscribed by the EPRI project manager responsible for the Buried Piping 

Integrity Group.

• Report to NEI the status of meeting the Initiative Implementation dates and any active 

deviations that do not meet the intent of the Initiative as required for the report to NSIAC 

(Appendix A)

• Report to INPO (EPIX/ICES) occurrences of leakage or adverse inspection findings in 

piping, and tanks within the scope of this Initiative as required for the report to NSIAC 

(Appendix A)

In order to meet the intent of the Initiative, utilities should:

• Participate in the industry programs that support the Initiative

• Contribute technical resources and executive leadership to industry efforts

• Communicate questions regarding the intent of the Initiative or the interpretation of this 

guideline to the Buried Piping Integrity Initiative Task Force. If a question relates to the 

text of the Initiative or a “shall” statement in this guideline, task force feedback on the 

questions would typically precede the development of a justification for deviation.
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• Communicate instances of significant leakage or adverse inspection findings of piping 

and tanks within the scope of the Initiative to the NEI and the EPRI Buried Piping 

Integrity Group Project Managers in a timely manner for the purpose of rapid 

dissemination of preliminary operating experience and to request immediate assistance as 

needed.

5.2 EPRI

EPRI performs the following functions in support of the Initiative:

• Support the real time assessment of operating experience as reported by utilities.

• Collect underground piping and tank inspection data obtained from utilities and evaluate 

its implications annually.

• Manage the research necessary to improve inspection technology for underground piping

and tanks

• Support repair/replacement technology as appropriate

• Provide a venue for identifying research and development needs, sharing operating 

experience, and other issues that have the potential for impact on the industry

• Compile and report to NEI the information necessary to make periodic reports to NSIAC

(Appendix A) on progress in the development of inspection technology

5.3 INPO

INPO performs the following functions in support of the Initiative:

• Incorporate within their plant evaluations a review of buried/underground piping and tank 

programs as applicable. The review should include piping and tanks that may not be 

safety related but are important to safety or contain potentially radiologically 

contaminated fluids.

• Communicate operating experience relative to underground piping and tank integrity

issues and other relevant information to the industry.

• Compile and report to NEI the operating experience information necessary to make 

periodic reports to NSIAC (Appendix A).

5.4 ANI

ANI performs the following function in support of the Initiative:

• Report significant recommendations from inspections related to underground piping and 

tank integrity and observations on Initiative implementation to NEI in support of the 

periodic report to NSIAC (Appendix A).
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5.5 NEI

NEI performs the following functions in support of the Initiative:

• Manage the industry’s regulatory interface on underground piping and tank issues of 

generic regulatory significance. 

• Manage the operation of the Buried Piping Integrity Working Group and Task Force. 

Task Force responsibilities include:

o Addressing questions regarding the interpretation of the Initiative 

o Judging whether deviations from Initiative requirements meet the intent of the 

Initiative 

o Evaluating important operating experience

o Evaluating the overall status of Initiative implementation as part of the report to 

NSIAC

• Communicate information relative to the Underground Piping and Tanks Integrity 

Initiative to the industry.

• Compile the information necessary to make periodic reports to NSIAC (Appendix A) on 

implementation of the Initiative.

• Communicate the periodic report to NSIAC on implementation of the Underground 

Piping and Tanks Integrity Initiative, industry operating experience, and inspection 

technology developments (Appendix A).

• Coordinate activities with utilities, EPRI, ANI, and INPO.
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6 INTENT OF THE UNDERGROUND PIPING AND TANKS INTEGRITY 

INITIATIVE

The following sections describe the activities and commitments that implement the Initiative 

actions presented in Section 3.3 of this document. Additional activities may also be necessary as 

industry experience and technology evolves. 

Additional information on the intent of the Initiative is provided by EPRI document, 

“Recommendations for an Effective Program to Control the Degradation of Buried Pipe”

(Reference 1). Although verbatim compliance with the EPRI guideline is not a commitment 

under the Initiative, the EPRI guidance forms the basis for the Initiative and provides additional 

details on the Initiative’s attributes and elements. References to the applicable sections of the 

EPRI document, where applicable, are provided in the descriptions in Section 6.2.

6.1 UNDERGROUND PIPING AND TANKS INTEGRITY INITIATIVE SCOPE

The following are clarifications and explanations of the intent of the scope of the Initiative:

• In general, the piping and tanks that are subject to the Underground Piping and Tanks 

Integrity Initiative are determined by starting with the total population of utility owned 

piping and tanks within the site boundaries and adjusting this population using the scope 

statement in section 3.1 and the clarifications in this section. This will result in some low 

consequence components such as those associated with water and sewage treatment 

facilities and storm drains to be subject to the Initiative, but the components may not need 

to be inspected. Appendix C provides guidance on inspection of in-scope components.

• Abandoned piping and tanks that are drained, not connected to an active system, and that 

are not known to be contaminated with licensed material are not within the scope of the 

Initiative.

• Piping and tanks that are below grade are excluded from the scope of the Initiative if they 

are accessible for direct inspection (see definition of Accessible).

• Portions of piping systems that are contained within building walls or basemats are not 

considered “underground” and are not within the scope of the Initiative. 

• Underground piping includes buried piping, and piping in vaults, trenches, tunnels, 

beneath buildings, or encased in concrete. 

• Piping owned by others that runs inside of the owner controlled area is not within the 

scope of the Initiative.

• If a vault is not accessible from inside a building, piping or tanks within the vault are 

considered outside of the building and within the scope of the Initiative even if the vault 

shares a wall with the building.
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• Owner’s piping located outside of the owner controlled area is not within the scope of the 

Initiative unless it is safety related or contains licensed material.

• Pump casings (the column or pipe that surrounds the actual pump) that penetrate the 

floors of buildings are not within the scope of the Initiative even if the casing is in contact 

with the soil.

• Some tanks that are safety related or contain licensed material sit at grade on a concrete 

donut shaped foundation with a center filled with compacted sand. The key factor that 

determines if such a tank is within the scope of the Initiative is the position of the bottom 

of the tank with respect to grade and the capability of detecting leaks by monitoring the 

tank level. If the tank contains licensed material, it is incumbent on the licensee to ensure 

that the tank is covered by either the Underground Piping and Tanks Integrity Initiative or 

the Ground Water Protection Initiative.

• Licensed material (from 10 CFR 20.1003) means source material, special nuclear 

material, or byproduct material received, possessed, used, transferred or disposed of 

under a general or specific license issued by the Commission.10 CFR 20.1003 . The term 

“licensed material” as used in this document is intended to be consistent with its meaning 

in the Ground Water Protection Initiative (NEI 07-07, Reference 3, Objective 2.2, Source 

Containing Licensed Material). Consistent with Regulatory Issue Summary RIS 2008-03 

“Return/Re-use of Previously Discharged Licensed Material” “licensed material” as 

applied in the Underground Piping and Tank Integrity Initiative does not include the 

concentration(s) of radioactive material previously released as a controlled, planned 

airborne or liquid radioactive effluent when it is returned to the facility in concentrations 

below the exempt concentration limits in 10 CFR 30. See the definition of licensed 

material (section 4.8) for more information.

6.2 UNDERGROUND PIPING AND TANKS INTEGRITY INITIATIVE IMPLEMENTATION

The goal of the Underground Piping and Tanks Integrity Initiative is to provide reasonable 

assurance of structural and leakage integrity of in-scope underground piping and tanks with 

special emphasis on components that contain licensed materials. The concept of reasonable 

assurance within the context of the Initiative means establishing and maintaining confidence in 

underground piping and tank integrity based on engineering judgment supported by facts, 

actions, knowledge, experience, and/or observations. It defines a level of confidence which is 

deemed to be adequate to support a particular position. 

The approach used to establish reasonable assurance should include leakage prevention by means 

of inspection as a key part of its process. It should be systematic and based on defined programs 

and processes that produce consistent results. The approach should be documented and 

supported by engineering evaluation, governing procedures, and risk ranking. It should be 

continuously validated by the results of examinations and fitness-for-service evaluations, and by 

the experience gained from required repairs and applied mitigation methods.

Although the Underground Piping and Tanks Integrity Initiative will provide a high level of 

confidence in the integrity of underground piping and tanks, it is not possible to guarantee that 
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there will be no leakage or no structural degradation in these components. This initiative is 

intended to reduce the probability and consequences of underground piping and tank issues as 

low as reasonably achievable.

Some utilities include tanks in the same program as buried piping and some have separate 

programs for tanks. The objective of the Underground Piping and Tanks Integrity Initiative is 

not to dictate a specific approach; rather it is to ensure that by whatever means utilities manage

these components, the applicable guidance in the programs meet the intent of the Initiative as 

explained in this document. 
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A. Activities within the Buried Piping Integrity Initiative Scope

6.2.1 Procedures and Oversight

The necessary governance and oversight responsibilities shall be in place by June 30, 2010. 

These include the procedures and oversight elements in section 3.3 and the following items.

• Clear lines of responsibility

The Buried Piping Integrity Program shall be established including the identification of a 

responsible executive who will carry out the senior level functions specified in the 

Initiative and this guideline.

• Process for justifying and approving exceptions to the Initiative

When a utility determines that a required element of the Initiative cannot be met, a 

technical justification for deviation shall be developed and retained with the utility’s 

program documentation. The technical justification should provide the basis for 

determining that the proposed deviation meets the same objective, or level of 

conservatism exhibited by the original work product, and should clearly state how long 

the deviation will be in effect. Justifications for deviation shall be reviewed and 

approved in accordance with the applicable plant procedures with concurrence from the 

responsible utility executive. 

Each utility shall report all approved justifications for deviation that are currently active 

at each of its plants to NEI semi-annually as part of the utility’s input to the NSIAC 

report. 

Note that the entire process for justifying deviations is described in Section 6.2.6. 

• Program Documents and Implementing Procedures

A Program Plan and associated procedures shall be developed to implement the 

Underground Piping and Tanks Integrity Initiative. The program documents and 

implementing procedures shall implement, as a minimum, the elements of the 

Underground Piping and Tanks Integrity Initiative (Section 3.3) and requirements in this 

document. Guidance for the specific content of the program document may be obtained 

from Sections 1.4.1 and 1.4.2 in the EPRI document on buried piping, 

“Recommendations for an Effective Program to Control the Degradation of Buried Pipe 

(Reference 1).”

6.2.2 Risk Ranking

A risk ranking process shall be used to understand site vulnerabilities and to help prioritize the 

selection of inspection locations. Risk ranking is performed by determining the likelihood of 

failure of each segment of applicable piping and combining that failure probability with the 

consequences of failure of that item. Components with high likelihood of failure and high 

consequences of failure should receive more attention than low ranked components. A 

description of a risk ranking process for buried piping is provided in Reference 1. 
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The risk ranking process shall incorporate the attributes listed in Section 3.3.A.2 of this 

document as augmented by the “shall” statement below as a minimum.

• The risk ranking shall be periodically reviewed and updated as necessary to reflect 

inspection results, changes in operating conditions, and design modifications. 

The risk ranking process shall also determine the likelihood and consequence of failure for each 

piping segment in order to prioritize inspections or other actions and should consider the 

following:

• Soil analysis data, when available to assess the likelihood of OD corrosion

• The potential for ID (fluid-side) corrosion and fouling 

• The “health” of the cathodic protection system. “Health” should be interpreted in the 

context of whether the system is performing its function as designed. 

• Over the line survey results. These results help assess the likelihood of OD corrosion.

• Whether piping and tanks contain fluids with licensed material. The risk ranking process

should place sufficient priority on these components such that the intent of the Initiative 

is met.

• The results of the Ground Water Protection Initiative risk ranking process. The NEI 

Ground Water Protection Initiative also contains a risk ranking process for systems, 

structures, and components, including underground piping and tanks, containing 

radioactive materials. The results of the Ground Water Protection risk ranking process 

should also be used as an input in inspection plan development.

Risk Ranking may be performed using software tools; several different software tools are 

available for this application. This guideline does not recommend or discourage any software 

system; but, regardless of the tool that is used, utilities should review the risk ranking results to 

ensure they reflect relative system priorities and are appropriate from an engineering judgment 

perspective. 

The initial risk ranking process shall be complete by December 31, 2010. 

6.2.3 Inspection Plan 

The goal of the inspection plan is to support an assessment of the pipe’s structural and leakage 

integrity and provide reasonable assurance that a piping segment will maintain this integrity 

between successive inspections. The results of risk ranking along with plant and industry 

experience, plant licensing commitments, and trending of past inspection data should be 

considered to define inspection locations, inspection methods, and inspection schedules (see 

reference 1). Other considerations such as access may also be considered when the relative risk 

rankings are similar. More guidance on inspection planning is provided in Appendix C.
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The inspection plan shall incorporate the attributes listed in Section 3.3.A.3 of this document as 

augmented by the “shall” statement below. 

• Where buried pipes are protected by a cathodic protection (CP) system, the CP system 

shall be periodically inspected and tested to assess its continued adequacy. 

Development of an inspection plan should consider the following:

• The capabilities of the inspection techniques used

• Industry and internal operating experience

• Piping design characteristics

• The condition of the piping inspected (if inspected previously) 

• The results of risk ranking performed for the Ground Water Protection Initiative

• Contingency plans that include

o Methods and criteria to assess the significance of inspection results considering 

the damage mechanism and licensing commitments.

o Repair and replacement options

• Input from a coating specialist

• Whether a CP system should be added to systems containing materials susceptible to 

degradation.

Sampling techniques and engineering evaluations based on known conditions of piping are an 

acceptable means of achieving reasonable assurance. 

The inspection plan shall be in place by June 30, 2011.

6.2.4 Plan Implementation

Plan implementation should consist of performing a condition assessment based on both 

inspection results and engineering evaluations. The inspections should be conducted at the most 

vulnerable locations determined using methods such as the risk ranking, results of cathodic 

protection and coating surveys, plant experience, etc. The combination of evaluations and 

inspections performed should provide reasonable assurance that the piping segment will maintain 

structural and leakage integrity until the next planned inspection. The inspection results should 

be documented and relevant photographs or video, when taken, should be filed to support 

inspection results. All inspection results (whether degradation exists or not) shall be reported to 

EPRI in the manner prescribed by the Buried Piping Integrity Group project manager.

Buried piping segments whose failures are inconsequential, and would cause no direct or 

collateral damage (such as potable water), may be considered “run to failure” and dispositioned 

accordingly. Safety related lines and those containing licensed materials should never be 

characterized as “run to failure”. Reference 1 provides more guidance on this categorization. 

Consider benchmarking piping segments characterized as “run to failure” against programs at 
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other utilities to check for consistent application. Note that segments categorized as “run to 

failure” are still considered within the scope of the Initiative and leaks and adverse inspection 

findings in these segments shall be reported in accordance with Appendix A. 

Inspections should consider the following:

• Inspecting the coating when a buried pipe is uncovered

• Performing a visual inspection of buried pipe when it is uncovered or entered for any 

reason in order to look for evidence of corrosion or damage.

• In situations where system operability or functionality is in question due to wall or weld 

degradation, examining the piping to determine remaining thickness. 

• Estimating a projection of future damage based on current inspection results and the time 

to the next planned inspection or repair.

• Categorizing the inspection results in support of a remaining life calculation. 

• Using the knowledge gained through the inspection and integrity assessment process to 

review and adjust as necessary the risk-informed ranking and the inspection plan.

The results of condition assessments should be an input to the Asset Management Plan.

Implementation of the inspection plan shall start no later than June 30, 2012 and the condition 

assessment of buried piping containing licensed materials shall be completed by June 30, 2013. 

Notes:

1. This milestone refers to inspection plans; it does not refer to reactor units or stations. 

Therefore, the start of implementation is defined as the completion of at least one direct 

examination of piping included in the inspection plan for a site.

2. The start of inspections applies to all in-scope lines and not just those that contain 

licensed material.

3. Implementation of the inspection plan should include at least one direct examination of 

piping included in the inspection plan. It is not sufficient that the direct examination has 

been planned; it also must also be completed. Previous inspections that meet the intent of 

a direct examination as defined in the industry’s inspection planning document qualify as 

starting even if they were performed prior to the approval of the Initiative or the formal 

development of the inspection plan. 

4. In accordance with Appendix C, the condition assessment does not require an actual 

examination of the component for other than high risk lines, but it should involve an 

engineering evaluation and associated documentation of the condition of the lines.
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6.2.5 Asset Management Plan

An asset management plan or plans addressing buried piping shall be developed and maintained. 

An asset management plan is a long range plan for managing the structural and leakage integrity 

of buried piping. Where the risk of failure is unacceptable, preventive and mitigative options 

should be implemented as part of the long range strategy.

The asset management plan for buried piping may be part of the overall site or fleet asset 

management plan. 

The asset management plan should be a living document that is periodically reviewed and 

updated as more plant data becomes available through physical assessments and other means and 

as industry knowledge and technology evolve. 

The asset management plan shall be reviewed and approved by an appropriate high level 

organization within the utility (such as the plant health committee).

Key elements of an Assessment Management Plan should include:

• Inspection plans

• Planned maintenance activities 

• Plans for repair

• Anticipated replacement 

One method to develop an asset management plan would be to categorize each buried line based 

on its risk rank, contents (licensed material, diesel oil, raw or minimally treated water, hazardous 

chemicals, off gas, etc), importance to power generation, results of cathodic protection testing,

and coating surveys, plant experience, etc. For example, each line would then be placed into 

categories such as:

• Components to be repaired or replaced with a planned schedule within an implementation 

plan.

• Components that need to be periodically inspected or monitored with a planned schedule.

• Components that are acceptable to run to leak and then repaired as needed (e.g., piping 

with low risk or low environmental impact. Plants should also consider public 

confidence concerns in applying this categorization.).

The plan should consider additional actions for a line such as:

• Inspect to determine the need to repair or replace.

• Add or enhance the cathodic protection.

• Add or enhance coating protection.
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• Actions to minimize the degradation of the inner surface of the piping.

• Add protection against heavy surface loads.

The Asset Management Plan for buried piping shall be in place by December 31, 2013. 

B. Activities within the Underground Piping and Tanks Integrity Initiative 

Scope

The expectations described in Section 6.2.A above (regarding procedures and oversight, risk 

ranking, inspection plans, plan implementation, and asset management) are applicable to the

components added by the Underground Piping and Tanks Integrity Initiative unless specifically 

stated otherwise below. The following sections (6.2.6 through 6.2.10) explain the intent of the 

Underground Piping and Tanks Initiative and provide additional guidance where appropriate. 

Note that the activities and milestones in sections 6.2.6 through 6.2.10 apply only to the 

additional components that were added by the Underground Piping and Tank Integrity Initiative 

when it extended the Buried Piping Integrity Initiative.
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6.2.6 Procedure and oversight

Procedure and oversight responsibilities applicable to the Underground Piping and Tanks 

Integrity Initiative, including associated plant programs, shall be revised to include in-scope 

tanks and piping by December 31, 2011. The following steps are one method of approaching 

this process.

• Identify the piping and tanks that fall within the scope added by the Underground Piping 

and Tanks Integrity Initiative.

• Identify the programs or processes in place, or develop new ones if necessary, to manage 

the leakage and structural integrity of these components. 

• Develop or amend existing overarching program or process documents to ensure that all 

the relevant programs are associated with the Underground Piping and Tanks Integrity 

Initiative and coordinated to control changes so that Initiative intent is managed and not 

inadvertently compromised. 

• Identify roles and responsibilities for the new program/process

• Develop a process for justifying any deviations to the Initiative elements documented in 

this guideline. Ensure the process meets the intent of Section A.6.2.1 and this section.

Procedures and oversight shall incorporate the attributes listed in Section 3.3.B.1 plus the “shall” 

statements in the following paragraphs.

• Process for obtaining review of Initiative and NEI 09-14 interpretations

Questions regarding the intent of the Initiative or the guidance in this document should be 

communicated to NEI. The Buried Piping Integrity Task Force will review the question 

and reply in a timely manner. The task force will also communicate interpretations of 

significant generic applicability to the industry as a means of facilitating consistent 

implementation of the Initiative. 

If a utility proceeds with an activity that does not meet the language of the Initiative or a 

“shall” statement in this document, a justification for deviation shall be processed in 

accordance with the remainder of this section. Note that a deviation may still meet the 

intent of the Initiative (see below) even if it does not meet the exact language of the 

Initiative. For example, it may be possible to risk rank buried piping without addressing 

every parameter in Section 3.3.A.2.

• Process for justifying and approving exceptions to the Initiative

When a utility determines that a required element of the Initiative or a “shall” statement 

in this document will not or cannot be met, a justification for deviation shall be developed 

and retained with the utility’s corrective action program. If a utility finds itself outside of 

a required Initiative element and takes immediate action to meet the element, a deviation 

justification is not required, but the condition should be entered into the corrective action 

program and the Buried Piping Integrity Task Force should be notified. Required 
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elements of the Initiative include the entire text of the Initiative (Sections 3.3.A and 

3.3.B) and all “shall” statements in this document (summarized in Appendix B).

The justification shall provide the basis for determining that the proposed deviation meets 

the same objective, or level of conservatism exhibited by the original requirement, and 

should clearly state how long the deviation will be in effect. Justifications for deviation 

shall be approved by the responsible utility executive.

To maintain the integrity of the deviation process and ensure a consistent approach to 

guideline implementation (or inability to implement), it is important for utilities to share 

deviations with the industry in an open and timely manner. Timely notification of 

deviations allows the industry to systematically review the issue for potential generic 

implications and take appropriate actions to facilitate consistent and appropriate 

implementation of guidance. The following guidance applies:

• Approved deviations shall be sent to NEI in a timely manner for review by the 

Buried Piping Integrity Task Force (BPITF). 

o The BPITF review is not an independent review or an approval. Their 

assessment is based on engineering judgment and experience.

• The BPITF will review the justification for deviation for the following items.

o Effect on guidance.

o Whether the deviation meets the intent of the Initiative. 

o Generic applicability.

• Generically applicable information relative to the justifications will be 

communicated to the industry.

• When the BPITF finds that the deviation does not meet the intent of the Initiative, 

the applicable utility and the Buried Piping Integrity Working Group will be 

informed. Semi-annually each utility shall report to NEI all active justifications 

for deviation at each of its plants that are judged to not meet the intent of the 

Initiative. This report is made as part of the utility’s input to the NSIAC report 

(Appendix A). 

• If the BPITF finds that the deviation does meet the intent of the Initiative, the 

utility will be informed but the deviation will not be reported to NSIAC. The 

justification should be retained with utility program documentation.

All requirements described in Section A. 6.2.1 are relevant to this section of the Underground 

Piping and Tanks Integrity Initiative except for implementation schedules.

6.2.7 Prioritization

The risk ranking process for buried piping will have been established as part of the Buried Piping 

Integrity Initiative. This process may not be able to incorporate underground piping or tanks 

because of the different parameters of concern. The process of risk ranking is referred to as 

“prioritization” within the Underground Piping and Tanks Integrity Initiative in recognition of 

this situation and the possibility that a risk ranking tool may not be in place when utilities start 
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the process. Greater use of engineering judgment is expected in the development of 

prioritization results. 

Prioritization shall incorporate the attributes listed in Section 3.3.B.2. Attributes that should also 

be considered when prioritizing components include:

• Age 

• Relevant industry operating experience

• Piping flow rate

• Tank volume

• Contents 

• Soil condition and chemistry

• Plant operating history

• Leakage history

• Internal corrosion consideration (such as flow accelerated corrosion for piping only, and 

microbiologically induced corrosion)

• Coating and lining

• Wet or alternately dry

Prioritization should be adjusted as appropriate to apply engineering judgment to the results. 

All requirements described in Section A. 6.2.2 are relevant to the Underground Piping and Tanks 

Integrity Initiative, except for implementation schedules. Prioritization of components that fall 

within the scope of the Underground Piping and Tanks Integrity Initiative shall be complete by 

June 30, 2012.

6.2.8 Condition Assessment Plan

The results of prioritization along with plant and industry experience, plant licensing 

commitments, and trending of past inspection data should be used to define inspection locations, 

inspection methods, and inspection schedules. Condition assessment plans shall incorporate the 

attributes listed in Section 3.3.B.3. The Condition Assessment Plan shall be in place by 

December 31, 2012. All requirements described in Section A. 6.2.3 are relevant to the 

Underground Piping and Tanks Integrity Initiative, except for implementation schedules. 

Guidance on inspection planning is provided in Appendix C.

6.2.9 Plan Implementation

Implementation of the Condition Assessment plan for components included within the scope 

added by the Underground Piping and Tanks Integrity Initiative shall start no later than June 30, 

2013. The condition assessment of underground piping and tanks containing licensed material 

shall be completed by June 30, 2014. 
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After prioritization is performed, the inspection process should address all piping and tanks 

within the scope of both the initial Buried Piping Integrity Initiative and the Underground Piping 

and Tanks Integrity Initiative in order to ensure the relative importance of the components are 

recognized and the more important components are inspected first when possible.

All requirements described in Section A. 6.2.4 are relevant to the Underground Piping and Tanks 

Integrity Initiative, except for implementation schedules.

6.2.10 Asset Management Plan

The Asset Management Plan for underground piping and tanks shall be in place by December 31, 

2014. All requirements described in Section A. 6.2.5 are relevant to the Underground Piping and 

Tanks Integrity Initiative, except for implementation schedule.
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7 REFERENCES

1. EPRI document, Recommendations for an Effective Program to Control the Degradation 

of Buried Pipe , December 2008

2. NACE (National Association of Corrosion Engineers) documents

a. SP0502-2008 (formerly RP0502), Pipeline External Corrosion Direct Assessment 

Methodology

b. SP0169-2007 (formerly RP0169), Control of External Corrosion on Underground 

or Submerged Metallic Piping Systems

c. RP0102-2002, In-Line Inspection of Pipelines

d. SP0207-2007, Performing Close-Interval Potential Surveys and DC Surface 

Potential Gradient Surveys on Buried or Submerged Metallic Pipelines

e. RP0288, "Standard Recommended Practice: Inspection of Linings on Steel and 

Concrete Tanks"

3. NEI 07-07, Industry Ground Water Protection Initiative – Final Guidance Document, 

August 2007

4. INPO 12-009, ICES Reporting Requirements and Standards

5. NUREG 1801, Volume 2 Section X1.M34, Generic Aging Lessons Learned (GALL) 

Report, Buried Piping and Tanks Inspection

6. ASTM G 158, "Standard Guide for Three Methods of Assessing Buried Steel Tanks"

7. ASTM E 1990, "Standard Guide for Performing Evaluations of Underground Storage 

Tank Systems for Operational Conformance with 40 CFR, Part 280 Regulations"

8. NLPA Standard 631, "Entry, Cleaning, Interior Inspection, Repair, and Lining of 

Underground Storage Tanks"

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APPENDIX A

REPORT TO NSIAC 

REPORT CONTENT

A report to NSIAC will be prepared semi-annually addressing the following four items:

1. Overview – developed by NEI semi-annually on the following topics as appropriate: 

o Notable information:

 Incidents that attract media or industry stakeholder attention 

 INPO feedback from plant evaluations 

 Important ANI feedback from plant evaluations

 Major piping or tank replacements and repairs as determined by NEI 

Buried Piping Integrity Task Force. Examples are major piping 

improvement projects where portions of service water systems were 

replaced with high density polyethylene piping or 6% molybdenum 

stainless steel)

o Assessment of availability of technology to support inspections

o Overall status of Initiative implementation, including the effect of active approved 

deviations to Initiative elements.

2. Progress on Initiative implementation and exceptions – utilities will report to NEI the 

status of implementation of each Initiative element at each of their plants using the 

approach described below. The report will be made semiannually (by January 31 and 

July 31) to NEI. NEI will collect and assemble the information.

o Report implementation status for each Initiative element and for each plant. The 

elements and the expected implementation dates are repeated below:

 Buried piping procedures and oversight in place by 6/30/10

 Buried piping risk ranking complete by 12/31/10

 Buried piping inspection plan in place by 6/30/11

 Underground piping and tanks procedures and oversight in place by 

12/31/11

 Buried piping inspection start by 6/30/12

 Underground piping and tanks prioritization complete by 6/30/12

 Underground piping and tanks condition assessment plan in place by 

12/31/12

 Condition assessment of buried piping containing radioactive materials 

complete by 6/30/13

 Underground piping and tanks inspection start by 6/30/13

 Buried piping asset management plan in place by 12/31/13
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 Condition assessment of underground piping and tanks containing 

radioactive materials complete by 6/30/14

 Underground piping and tanks asset management plan in place by 

12/31/14

o Document the status for each implementation date as follows:

 Will extend the implementation date or have extended

 Implementation by the due date is at risk

 On schedule to meet date

 Complete

o Describe each active deviation that does not meet the intent of the Underground 

Piping and Tanks Integrity Initiative. Note that the existence of an approved 

deviation to an implementation date does not change the fact that the date will not 

be met. If an implementation date is not going to be met, it shall be reported as 

such until the implementation is completed. 

3. Industry experience and learning – Utilities will report the information below to INPO. 

INPO will collect the information and report the results to NEI.

o Utilities will enter operating experience related to the items below into the INPO

EPIX/ICES database when instances occur. Entries should be made in a 

timeframe consistent with EPIX/ICES timing requirements (Reference 4). 

 Every leak from underground piping and tanks within the scope of this 

Initiative

 Significant leaks from underground piping and tanks that are within the 

scope of this Initiative: Significant leaks are defined as those which meet 

either of the following criteria

- Result in concentrations that could exceed the regulatory 

concentrations or limits established by the NRC or EPA., or 

- Result in voluntary communication under the industry Ground 

Water Protection Initiative, or 

- Result in the system or component being out of service

 Adverse inspection findings: defined as indications from inspections that 

require immediate repair or repair within one cycle

o Each instance will be categorized into one of the following five areas depending 

upon the piping segment or tank affected (where more than one area applies, use 

the one that appears highest in the list below).

 Safety related 

 Contains licensed material

 Contains environmentally hazardous fluids (e.g., oils, chemicals, nonradioactive fluids) 

 Components categorized as not “run to failure”

 Components categorized as “run to failure”

4. Progress on inspection technology development – EPRI will assemble the information 

below and report the results to NEI.
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o Identify each technology that is being researched for possible use in inspections

o Describe the development and implementation status of each identified inspection 

technology.

GENERAL

Information on leakage from applicable buried/underground piping and tanks using the above 

criteria will be collected beginning for events that occurred in 2009. Information on Initiative 

implementation and inspection technology will be collected beginning in 2010.

Information will be collected from utilities, INPO, ANI, and EPRI and sent to NEI semiannually. NEI will assemble a report for Buried Piping Integrity Task Force review and 

assessment. The objective is to:

• Prepare an NSIAC presentation.

• Share implementation status and operating experience with the industry as appropriate.

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APPENDIX B

NEI 09-14 REQUIREMENTS

Section Requirement

3.3 In order to meet these goals, every utility shall implement measures or program(s) to 

satisfy the elements and associated key attributes in Sections 3.3.A and B. The 

language in sections 3.3.A and B below documents the text of the Underground

Piping and Tanks Initiative as approved by NSIAC...

Note that the entire text of sections 3.3.A.1 thru 3.3.A.5 and 3.3.B.1 thru 

3.3.B.10 is a requirement under the Underground Piping and Tanks 

Integrity Initiative since these sections constitute the text of the Initiative 

as approved by NSIAC. In the interest of brevity, the text from these 

sections is not captured in this table.

3.5 Every utility shall ensure that activities associated with the Underground Piping and 

Tanks Integrity Initiative and this document are implemented at its nuclear power 

plants in accordance with the intent of the Initiative and the implementation dates 

specified therein.

3.5 If a plant cannot or will not implement any part of the Initiative (Sections 3.3.A and 

B) or a “shall” statement in this document, a justification for deviation from the 

Initiative shall be developed and processed in accordance with Section 6.1.

5.1 Utilities shall perform the following actions in support of the Initiative:

• Implement the actions required by the Initiative (Section 3.3 and all “shall” 

statements in this document).

• Process a justification for deviation (Section 6.1.1) whenever an action 

required by the Initiative or a “shall” statement in this document cannot be 

met.

• Report all results from inspections performed in accordance with the Initiative 

in the manner proscribed by the EPRI project manager responsible for the 

Buried Piping Integrity Group.

• Report to NEI the status of meeting the Initiative Implementation dates and 

any active deviations that do not meet the intent of the Initiative as required 

for the report to NSIAC (Appendix A)

• Report to INPO (EPIX/ICES) occurrences of leakage or adverse inspection 

findings in piping, and tanks within the scope of this Initiative as required for 

the report to NSIAC (Appendix A)

6.2.1 The necessary governance and oversight responsibilities shall be in place by June 30, 

2010.

6.2.1 The Buried Piping Integrity Program shall be established including the identification 

of a responsible executive who will carry out the senior level functions specified in 

the Initiative and this guideline.
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Section Requirement

6.2.1 When a utility determines that a required element of the Initiative cannot be met, a 

technical justification for deviation shall be developed and retained with the utility’s 

program documentation.

6.2.1 Justifications for deviation shall be reviewed and approved in accordance with the 

applicable plant procedures with concurrence from the responsible utility executive.

6.2.1 Each utility shall report all approved justifications for deviation that are currently 

active at each of its plants to NEI semi-annually as part of the utility’s input to the 

NSIAC report.

6.2.1 A Program Plan and associated procedures shall be developed to implement the 

Underground Piping and Tanks Integrity Initiative. 

6.2.1 The program documents and implementing procedures shall implement, as a 

minimum, the elements of the Underground Piping and Tanks Integrity Initiative 

(Section 3.3) and requirements in this document.

6.2.2 A risk ranking process shall be used to understand site vulnerabilities and to help 

prioritize the selection of inspection locations. 

6.2.2 The risk ranking process shall incorporate the attributes listed in Section 3.3.A.2 of 

this document as augmented by the “shall” statement below as a minimum.

• The risk ranking shall be periodically reviewed and updated as necessary to 

reflect inspection results, changes in operating conditions, and design 

modifications. 

6.2.2 The initial risk ranking process shall be complete by December 31, 2010.

6.2.2 The risk ranking process shall determine the likelihood and consequence of failure 

for each piping segment in order to prioritize inspections or other actions

6.2.3 The inspection plan shall incorporate the attributes listed in Section 3.3.A.3 of this 

document as augmented by the “shall” statement below. 

• Where buried pipes are protected by a cathodic protection (CP) system, the 

CP system shall be periodically inspected and tested to assess its continued 

adequacy.

6.2.3 The inspection plan shall be in place by June 30, 2011.

6.2.4 Note that segments categorized as “run to failure” are still considered within the 

scope of the Initiative and leaks and adverse inspection findings in these segments 

shall be reported in accordance with Appendix A.

6.2.4 All inspection results (whether degradation exists or not) shall be reported to EPRI in 

the manner proscribed by the Buried Piping Integrity Group project manager.

6.2.4 Implementation of the inspection plan shall start no later than June 30, 2012 and the 

condition assessment of buried piping containing licensed materials shall be 

completed by June 30, 2013.

6.2.5 An asset management plan or plans addressing buried piping shall be developed and 

maintained. 

6.2.5 The asset management plan shall be reviewed and approved by an appropriate high 

level organization within the utility (such as the plant health committee).

6.2.5 The Asset Management Plan for buried piping shall be in place by December 31, 

2013. 

6.2.6 Procedure and oversight responsibilities applicable to the Underground Piping and 

Tanks Integrity Initiative, including associated plant programs, shall be revised to 
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Section Requirement

include in-scope tanks and piping by December 31, 2011.

6.2.6 Procedures and oversight shall incorporate the attributes listed in Section 3.3.B.1 plus 

the “shall” statements in the following paragraphs.

6.2.6 If a utility proceeds with an activity that does not meet the language of the Initiative 

or a “shall” statement in this document, a justification for deviation shall be 

processed in accordance with the remainder of this section.

6.2.6 When a utility determines that a required element of the Initiative will not or cannot 

be met, a justification for deviation shall be developed and retained with the utility’s 

corrective action program. 

6.2.6 The justification shall provide the basis for determining that the proposed deviation 

meets the same objective, or level of conservatism exhibited by the original 

requirement, and should clearly state how long the deviation will be in effect.

6.2.6 Justifications for deviation shall be approved by the responsible utility executive.

6.2.6 Approved deviations shall be sent to NEI in a timely manner for review by the Buried 

Piping Integrity Task Force (BPITF).

6.2.6 Semi-annually each utility shall report to NEI all active justifications for deviation at 

each of its plants that are judged to not meet the intent of the Initiative. 

6.2.7 Prioritization shall incorporate the attributes listed in Section 3.3.B.2. 

6.2.7 Prioritization of components that fall within the scope of the Underground Piping and 

Tanks Integrity Initiative shall be complete by June 30, 2012.

6.2.8 Condition assessment plans shall incorporate the attributes listed in Section 3.3.B.3. 

6.2.8 The Condition Assessment Plan shall be in place by December 31, 2012.

6.2.9 Implementation of the Condition Assessment plan for components included within 

the scope added by the Underground Piping and Tanks Integrity Initiative shall start 

no later than June 30, 2013. 

6.2.9 The condition assessment of underground piping and tanks containing licensed 

material shall be completed by June 30, 2014. 

6.2.10 The Asset Management Plan for underground piping and tanks shall be in place by 

December 31, 2014. 

App A If an implementation date is not going to be met, it shall be reported as such until the 

implementation is completed.

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APPENDIX C

GUIDANCE FOR INSPECTION AND CONDITION ASSESSMENT OF 

BURIED AND UNDERGROUND PIPING AND TANKS
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TABLE OF CONTENTS

1. PREFACE......................................................................................................................3

2. PURPOSE.....................................................................................................................3

3. BACKGROUND.............................................................................................................3

4. SCOPE..........................................................................................................................4

5. TERMS AND DEFINITIONS ..........................................................................................5

6. BURIED AND UNDERGROUND PIPING INSPECTION/CONDITION ASSESSMENT RA 

FLOW CHART-DESCRIPTION.......................................................................................9

7. TANKS ........................................................................................................................19

8. REFERENCES.............................................................................................................20
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1. Preface

This document provides industry guidance for the determination of reasonable assurance for 

structural and/or leakage integrity for buried and underground piping and tanks. The criteria and 

guidelines presented in this document were developed as a consistent basis for establishment of 

what is necessary to provide “reasonable assurance of integrity”. 

2. Purpose

The purpose of this document is to provide a technically based approach for development of 

inspection and condition assessment plans that establish reasonable assurance of structural and/or 

leakage integrity of buried and underground piping and tanks through the application of the 

results of both indirect inspections and direct examinations. The approach is programmatically 

founded in the precepts established in the “Recommendations for an Effective Program to 

Control the Degradation of Buried and Underground Piping and Tanks (1016456, Revision 1-

EPRI Product ID: 1021175) and utility site specific program documents. This document is 

intended to establish reasonable assurance for scoped buried and underground piping systems 

and tanks; optimizing the inspection scope, while not requiring 100% inspection.

3. Background 

Reasonable assurance is an industry concept used to achieve increased confidence in the 

capability of a structure, system or component (SSC) to perform its intended function. 

Reasonable assurance does not equate to absolute assurance or confidence. Rather, reasonable 

assurance collects appropriate data/insights/information to support the establishment of increased 

confidence. Situations may occur where sufficient data cannot be easily collected; in these cases, 

the available data may be supplemented with additional insights to bolster a technical foundation 

of reasonable assurance. If available information (even with supplemental insights) is 

insufficient to support a conclusion of reasonable assurance, then additional actions must be 

taken to achieve reasonable assurance. Ultimately, the establishment of reasonable assurance is 

the obligation of the owner. This guideline provides insights to achieve consistency among 

industry users to identify what actions are generally necessary to establish reasonable assurance 

for structural and/or leakage integrity for buried and underground piping and tanks.

Reasonable assurance of integrity in buried and underground piping systems and tanks 

containing licensed material or non-licensed material is obtained when activities such as an 

engineering evaluation (including a Fitness-for-Service evaluation), indirect inspections of 

underground components, direct examination and remediation (if necessary), are performed. 

Such a combination of activities will provide a high level of confidence that the structural and 

leak integrity of the buried and underground piping systems and tanks, will be managed and 

effectively maintained.

A reasonable assurance of integrity process is based on defining systems that are in scope, risk 

ranking these systems, and then identifying a sample of locations in these systems for 

inspections. It relies on engineering analyses, expert judgment, operating experience, and 

groundwater protection program data to determine what regions of the buried and underground 

pipes or tanks are most vulnerable to degradation and adequately characterizing the vulnerability 
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so that appropriate preventive, mitigating or corrective actions may be taken. This process is 

based on risk identification and inspection sampling intended to greatly reduce the potential for 

unacceptable leakage or failures in the most susceptible systems. 

Engineering evaluation is an important part of the “reasonable assurance of integrity” process. 

The engineering evaluation will consider but is not limited to items such as high consequence 

and/or likelihood areas, previous inspection results, fabrication practices, material type, backfill, 

coating, soil condition, water levels, water and soil chemistry, cathodic protection, connection to 

the grounding grid, operational history, industry operating experience, site operating experience 

and groundwater protection program data. For underground pipe, exterior environments that 

should be considered in the engineering evaluation include presence and type of insulation, 

potential for water intrusion, humidity, temperature, coating, condition of the tunnel or vault 

(e.g., heavily cracked or spalled concrete, etc), and condition of the pipe supports (corroded 

rollers, loose pipe supports, loose or corroded anchor bolts, etc). This engineering evaluation will 

identify the risk of potential leakage, the most probable locations, and/or areas of likely 

susceptibility. The evaluation will also identify the potential consequences that could result if a 

leak occurred. With this information, an inspection plan can be developed and implemented that 

provides information regarding the condition of the structure, system or component. The 

inspections can be indirect in that they will provide information on the condition of the pipe 

remotely – from ground level or from an exposed section of pipe that is distant or remote from 

the pipe location of interest. Inspections include a direct examination of the pipe wall and a 

visual inspection of the outer surface coating to determine coating integrity. Direct examination 

can also be achieved using an in-line vehicle (or Pipeline Inspection Gauge “PIG”) deployed 

with demonstrated direct examination equipment that is capable of detecting both OD and ID 

degradation at the location of interest that may challenge structural or leakage integrity.

The specific inspections and examinations that are performed will be based on the type of 

degradation observed or expected, the susceptibility of the pipe to leakage or breaks, the 

consequences of a leak or break, and the location of the pipe. The scheduling of re-inspection 

and re-examination is also dependent on the engineering determination of susceptibility, 

consequences, and the results of the initial inspection or examination. 

4. Scope

The scope of this guidance includes all piping and tanks covered by the NSIAC Underground 

Piping and Tanks Integrity Initiative. The Industry Initiative encompasses:

• all piping that is below grade, in direct contact with the soil and contains any fluid

• underground piping and tanks that are outside of buildings and below grade (whether or 

not they are in direct contact with the soil) and safety related or contain licensed material 

or are known to be contaminated with licensed material. 
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5. Terms and Definitions 

5.1. Baseline Inspections - Inspection of new or replaced pipe or components that have 

not previously been involved in plant operations. 

5.2. Corrosion Rate (CR) - The rate of corrosion occurring over a defined period of time.

5.3. Direct Examination - A Nondestructive Evaluation (NDE) examination where the 

NDE sensor(s) is in immediate contact with or in close proximity to the section of the 

component being examined. Results provide some degree of quantitative 

measurement of wall thickness or discontinuity size. Direct examinations can be 

performed from the interior or exterior surface. Detection and characterization 

capabilities vary by NDE method as well as by specific NDE technique. Examples of 

NDE methods include ultrasonics, eddy current, radiography, visual and various 

electromagnetic techniques. Visual examinations should be supplemented with NDE 

or engineering judgment that addresses the condition of the pipe wall. 

 

5.4. Fitness-for-Service (FFS) - A technical evaluation of direct examination data to 

determine acceptable flaw size, degradation rate, remaining life, and the time to the 

next inspection or repair/replacement/mitigation. 

5.5. Highest Susceptible Locations - The highest likelihood and consequence risk ranked 

segments or zones as defined in the buried piping susceptibility analysis and risk 

ranking database. 

5.6. Indirect Inspection – Survey techniques used to assess the likelihood of degradation 

without having direct access to the section of the component being examined. These 

inspections typically measure surrounding conditions that may be indicative of 

corrosion or damage. Results are typically qualitative and less accurate than direct 

examinations. Examples of indirect inspection methods include over-the-line surveys 

and for the purpose of this document, long range guided wave.

5.7. Initial Inspection - The inspection of pipe or components that have been in service 

but have not been previously inspected. 

5.8. Inspection Program - A systematic evaluation of in-scope components using various 

techniques (e.g., ultrasonic testing (UT), radiographic testing (RT), visual testing 

(VT), leak testing (LT), eddy current testing (ET)).

5.9. Lg –The total length of piping associated with a group of lines.

5.10. L indirect –The total length of pipe associated with a group of pipe lines that have 

been indirectly inspected.

5.11. Line Grouping - A process that may be used to optimize inspection scope and 

schedule duration. Lines/segments/zones are grouped based on various attributes, 
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such as but not limited to process fluid, pipe material, coatings, depth, age, 

soil/backfill, etc.

5.12. Next Scheduled Inspection (NSI) - The time duration until another inspection of the 

pipe line group is required. 

5.13. Opportunistic Inspection – An inspection performed when buried or underground 

components are exposed or excavated due to another activity providing an 

opportunity to inspect and document the results for a program component.

5.14. Piping Segment - Portions of buried piping systems that are grouped together for risk 

ranking purposes based on similarities such as installation, manufacture, or 

environmental conditions. Some risk ranking methods may use other terms to refer to 

piping segments, such as zones. 

5.15. Post Assessment - An assessment of all indirect and direct examination results 

including a FFS evaluation that will determine the projected structural and leakage 

integrity of a pipe. 

5.16. Remaining Life (RL) - The time period until the pipe wall thickness is no longer 

acceptable. 

5.17. Visual Inspections - Direct observation by inspectors or by the use of remote visual 

inspection devices. Visual inspections may include the use of pit gauges to assess the 

extent of any degradation noted. 
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Figure 6-1

Buried and Underground Piping Inspection/Condition Assessment Reasonable Assurance 

(RA) Flow Chart
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Figure 6-2

Buried and Underground Piping Inspection/Condition Assessment Reasonable Assurance 

(RA) Flow Chart
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6. Buried and Underground Piping Inspection/Condition Assessment RA Flow 

Chart-Description

6.1. Buried Piping Program Susceptibility Analysis and Risk Ranking

1. Susceptibility Analysis and Risk Ranking are used to determine the overall 

likelihood and consequence of a line, segment or zone failure. 

2. This evaluation is based on detailed site specific information and provides a risk 

assessment of all piping within the program scope. 

3. The following potential exclusions or exceptions from the inspection scope may 

be considered based on the susceptibility and risk ranking process. The basis for 

the exclusion should be documented:

a. Segments or zones constructed of materials of minimal susceptibility to 

the associated ID and OD degradation mechanisms like titanium and super 

austenitic stainless (e.g., AL6XN or 254 SMO).

b. Piping sections that are hydrostatically tested in accordance with 49 CFR 

195 subpart E on an interval not to exceed 5 years.

c. Segments or Zones of Stainless Steel, HDPE, other Polymer, or 

Cementitious or Concrete materials in Controlled Low Strength Materials 

(flowable fill) or Higher Long Term Compressive Strength Materials 

(Concrete).

d. Required Inspections for Segments or Zones of Carbon Steel materials 

may be reduced by 50% if in Controlled Low Strength Materials (flowable 

fill) or Higher Long Term Compressive Strength Materials (Concrete). 

The remaining inspection may be performed by excavating the backfill 

and examining the pipe or by excavating the soil around the backfill and 

examining the backfill materials. The corrosion rate of piping that is fully 

encased in Controlled Low Strength Materials (flowable fill) or Higher 

Long Term Compressive Strength Materials (Concrete) that is not 

degraded is expected to be minimal. 

e. Lines or segments with no consequence of failure. 

6.2. Create Line Groupings

1. The purpose for the grouping of lines is to be able to extrapolate inspection results 

from one or more examinations to the rest of the group, optimizing the number of 

excavations.

2. Separate segments or zones by process fluid (e.g., Tritiated, Service Water, & Oil 

lines would be grouped separately; Corrosive vs. non-corrosive fluid, for instance 

chemical feed would be grouped separately from condensate and separately from 

tritiated circulating water piping)
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3. Further separate or create groups of lines with similar physical attributes based on the 

following :

a. Material (e.g., Carbon Steel, Stainless Steel, Plastic, Fiberglass, and 

Aluminum would be grouped separately) Note: Consideration should be given 

to the corrosion resistance of specific materials like the different grades of 

stainless steels.

b. Coating type/age/condition

i. ID coating, type/age/condition

ii. OD coating, type/age/condition

c. Line depth (the basis for this grouping is the effect of live loads, and 

overburden): 

i. < 10ft below grade -- Can see the effects of live loads 

ii. > 10ft below grade 

d. Pipe Age (e.g., Inspections on newer lines should not be used to justify 

reasonable assurance on older lines).

e. Location in similar soil conditions (e.g., Lines in close proximity to one 

another in the same underground path/fill trench, backfill)

f. Level of Cathodic protection, availability and operating history

g. Operating Conditions

i. Temperature (e.g., lines that undergo cyclic temperature changes 

and/or are >100F would not be grouped with ambient temperature 

lines). 

ii. Operating frequency, and durations (e.g., continuous flow,. 

infrequent/outage only, stagnant or dead leg)

h. Pipe joining methods (e.g., socket vs butt welds or threaded connections & 

could be a consideration for the adequacy of the external coating application)

4. For underground piping additional considerations for line group includes:

a. Presence and type of insulation

b. Potential for ground or rain water intrusion

c. Tunnel or vault temperature and humidity

d. Condition of the tunnel or vault structure

e. Type of deadweight support (e.g., pipe hangers versus continuous)

f. Condition of the pipe supports (rollers, anchor bolts, hangers, etc)

5. It is not required to separate or create new groups for each category listed in 6.2.3 

and/or 6.2.4 above. 

6. Each segment or zone should be included in a Line Group.
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7. Documentation is required to support the basis for each line grouping. 

8. Inspections would be performed on the highest susceptible locations in each group. 

6.3. Indirect Inspection

1. Indirect inspections, when feasible, are an available option for determining the 

number and location of direct examinations that are required.

2. Indirect inspections are not required and the owner can go straight to the maximum 

direct examinations per the respective category of that line group. The number of 

required direct examinations can be determined using figure 6.2 or section 6.5.2 

below. 

3. Indirect Inspection Selection is based on the highest susceptible locations in a line 

group. 

4. Review each of the Indirect Inspection techniques per station or industry examination 

guidelines for determining applicable or optimum methods for each grouping or 

individual segments/zones.

5. Review historical cathodic protection survey data and segment or zone location 

accessibility in order to refine the inspection selection areas. 

6. Review the Groundwater Protection Program data. 

7. Indirect inspection measurements should be referenced to precise geographic 

locations and documented so that inspection results can be used for excavation and 

direct examinations. Indications from inspections should be aligned with other results, 

drawings and structures. 

8. Verification of the indirect inspections indications should be done using the direct 

examination results. At least one direct examination will be performed in each high 

risk line grouping. 

6.4. Classify Indirect Inspection Results

1. Criteria for classifying indirect inspection results should be established. 

2. The criteria for classifying the severity of indications should take into account the 

indirect inspection techniques used and the conditions surrounding the pipe segment. 

The following general classifications may be used: 

a. Severe – indications having the highest likelihood of active corrosion activity

b. Moderate – possible pipeline corrosion activity

c. Minor – the lowest likelihood of active corrosion activity.

3. The capability and accuracy of the inspection method used must be considered as part 

of the engineering evaluation. 
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6.5. Direct Examination Initial Sample Size

1. When indirect inspections (for example a combination of Guided Wave and Above 

Ground Coating Surveys), covered greater than 50% of total (group) length including 

the highest susceptibility locations and where no severe indication (Section 6.4) is 

identified; one direct examination of the highest susceptible location to confirm the 

indirect inspection results would be required for each high risk line grouping, 

irrespective of the total line length. If an acceptable direct examination was achieved 

(i.e., Post Examination Assessment), then reasonable assurance could be 

demonstrated. 

2. When indirect inspections covered less than 50% of total length of a pipe group and 

where no severe indication is identified:

a. For those High Risk Ranked lines that are safety related or contain Licensed 

Material or are known to be contaminated, that have pipe groups with total 

lengths of piping less than approximately 500’ (ft.), then one direct 

examination of the highest susceptible location, with acceptable results, may 

be sufficient to demonstrate reasonable assurance. In selecting the location of 

the direct examination, consideration can be given to the accessibility of 

examination locations. 

b. For those High Risk Ranked lines that are safety related or contain Licensed 

Material or are known to be contaminated, that have pipe groups with total 

lengths of piping greater than approximately 500’ (ft.), but less than 2500’ 

(ft.), two direct examinations of the highest susceptible locations, with 

acceptable results, may be sufficient to demonstrate reasonable assurance. In 

selecting the location of the direct examination, consideration can be given to 

the accessibility of examination locations. 

c. For those High Risk Ranked lines that are safety related or contain Licensed 

Material or are known to be contaminated, that have pipe groups with total 

lengths of piping greater than approximately 2500’ (ft.), three direct 

examinations of the highest susceptible locations, with acceptable results, may 

be sufficient to demonstrate reasonable assurance. In selecting the location of 

the direct examination, consideration can be given to the accessibility of 

examination locations.

d. For those lines that are High Risk Ranked and are not safety related, do not 

contain Licensed Material or are not known to be contaminated that have pipe 

groups with total lengths less than approximately 500’ (ft.), one direct 

examination of the highest susceptible location, with acceptable results, may 

be sufficient to demonstrate reasonable assurance. In selecting the location of 

the direct examination, consideration can be given to the accessibility of 

examination locations. 

e. For those lines that are High Risk Ranked and are not safety related, do not 

contain Licensed Material or are not known to be contaminated that have pipe 

groups with total lengths greater than approximately 500’ (ft.), two direct 

examinations of the highest susceptible locations, with acceptable results, may 
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be sufficient to demonstrate reasonable assurance. In selecting the location of 

the direct examination, consideration can be given to the accessibility of 

examination locations. . 

f. For those lines that are Medium and Low Risk Ranked, a monitoring plan 

should be established and direct examinations performed on an opportunistic 

basis to determine reasonable assurance.

3. For indirect inspections that indicate severe levels of corrosion activity, categorize 

locations for direct examination and proceed to section 6.6. 

4. For indirect inspections that indicate moderate and minor levels of corrosion activity 

the direct examination or examinations in section 6.5.2 would be focused on the 

highest area of indicated degradation.

5. Where indirect inspections that evaluate wall thickness are performed at the most

susceptible locations in a group, and the results of such inspections indicate NO or 

MINOR likelihood of corrosion activity, then confirmation of the indirect inspection 

results may be obtained from a direct examination of another indirect inspection 

location in the same group (where the same inspection technique was used). This can 

be allowed when accessibility issues exist for conducting a direct examination.

Using the figure below to illustrate this concept; a guided wave shot is taken in 

Excavation 1 showing only “minor” indications at “B” and “D”. A direct exam is 

performed that validates these results, and the remaining life is acceptable. A second 

set of guided wave shots is taken through a wall penetration (highest susceptible 

location), showing minor indications at “A” and “C”. The pipe condition and 

indications at “A” and “C” would be considered validated by the direct examination 

completed in Excavation 1 with an acceptable remaining life. A second excavation 

would not be required to validate indications “A” and “C”. To provide additional 

assurance of pipe integrity for all of these indications; one or more of the monitoring 

activities listed in section 6.8-3 should be periodically performed.
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6.6. Direct Examination Selection

The objective of direct examination is to assess the extent of corrosion activity for line 

segments selected for examination based on the risk assessment and indirect inspections, 

when performed. When no significant degradation is found from a direct examination the 

remaining service life and next scheduled inspection should be calculated using the guidance 

in the following sections. 

1. Indirect inspections results should be used in determining the priority of direct 

examinations. Below is an example of criteria used for prioritizing direct 

examinations based on the severity of indications from the indirect inspections:

a. Severe Indications – Initiate Direct Examination Plan with Contingencies for 

Mitigating Action for:

i. Severe indications in close proximity 

ii. Severe indications in a region with multiple moderate indications

iii. Isolated severe indications in a high risk region or area

iv. Moderate indications in a region of high risk, prior leaks or severe 

corrosion

b. Moderate Indications – Scheduled Action Required

i. Isolated severe indication in a low risk region

ii. Groups of moderate indications

iii. Groups of minor indications in a medium risk region

iv. Groups of minor indications in close proximity 

c. Minor Indications – Monitor

i. All remaining indication scenarios 

2. If no Indirect Inspections were performed for a group, then selection of the direct 

examination locations is based on the highest susceptible location of each high risk 

line group considering location accessibility. Review historical cathodic protection 

survey data or other relevant parameters to refine the direct examination area 

determination. 

3. Direct examinations resulting from excavations should include coatings inspections 

by a person trained and experienced in coating condition assessment. 

4. At least one Direct Examination is required for each High Risk Line Group in order 

to establish reasonable assurance for the Group.

5. A Direct Examination at an individual excavation for one pipe/group will assess a 

minimum 10’ (ft.) length of pipe, if feasible. When there is more than 1 pipe/group in 

an excavation, each pipe/group that receives an examination accounts for a separate 

direct examination. If multiple lines of the same pipe grouping are exposed during 

excavation the direct examination length may be broken up between the pipes in that 
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group. For example, a length of 5’ (ft.) is examined on two lines of the same group 

would count for one direct examination for that group.

6.7. Inspection Sample Expansion Considerations

When a pipe segment or zone has degradation detected by direct examination that exceeds 

the acceptance criteria in sections 6.8 and 6.9:

1. Determine the extent of the degradation by mapping the axial and transverse lengths 

and depths of the degraded area.

2. Review the indirect inspection results for the affected segment or zone and determine 

if additional excavation is required to perform direct examination of other areas with 

severe or moderate indications. 

3. Determine any segments or zones that share the same degradation susceptibility 

characteristics and schedule additional direct examinations. The timing of the 

additional examinations should be based on the severity of the degradation identified 

and should be commensurate with the consequence of a leak or loss of function. 

4. Scope expansion must be sufficient to provide confidence that the extent of condition 

reasonably bounds the degradation.

5. Document the findings and actions in the appropriate corrective action program. 

6.8. Post Examination Assessment

The purpose of the post assessment process is to define the inspection interval (time to Next 

Scheduled Inspection or NSI), assess the effectiveness of the program, and then feed the 

results back to the pre-assessment step to revise the risk ranking of buried and underground 

pipe segments or zones and tanks as a continuous improvement process. The cumulative goal 

of the evaluations for a piping group is to complete a post assessment; including a fitness for 

service evaluation, that determines the remaining life and next scheduled inspection interval to 

provide quantitative reasonable assurance for that group.

1. The assessment of the examination results should be made using a Fitness-for-Service 

(FFS) evaluation. Any degradation found during a direct examination should be 

appropriately documented. 

2. The FFS evaluation performed will apply to all lines, segments, or zones in the group.

a. When direct wall thickness measurement meets tmin & tmeas is >87.5% of tnom 

no FFS evaluation is required, unless active degradation is identified. 

b. When direct wall thickness measurement meets tmin & tmeas is <87.5% of tnom:

i. Perform an FFS evaluation

ii. Evaluate cause of degradation (consider all variables-material, backfill, 

coatings, installation, etc.)

iii. Evaluate the extent of degradation (localized verses global) 
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iv. Evaluate the need for scope expansion

v. Enter into the corrective action program

c. When direct wall thickness measurement does NOT meet tmin:

i. Evaluate cause and extent of degradation 

• Inspection scope expansion (See section 6.7)

• Determine the Extent of Condition

• Repair degraded areas

• Evaluate potential mitigation strategies

• Enter into the corrective action program

3. Monitoring activities should be considered as part of the reasonable assurance 

programmatic or compensatory actions. Examples for the justification of the 

scheduling/deferral of reasonable assurance direct examinations are:

• Increased Ground Water Initiative related well monitoring frequency

• Enhanced Cathodic Protection

• Enhanced over the line or Area Potential Earth Current (APEC) Surveys 

• Soil Analysis

• Coating Scans

• Flow/pressure testing

• Guided Wave inspections 

• Boroscope or robotic inspections of the pipe inside diameter

• Corrosion Probes

• Leak Testing (Acoustic monitoring, etc.)

• Vault conditions for underground piping

6.9. Fitness for Service (FFS) Evaluation

The purpose of the FFS evaluation process is to provide guidelines for evaluating wall 

thickness degradation in safety and non-safety related components. Engineering should use 

these guidelines, or other applicable methodologies, when establishing the acceptance criteria 

or refining the acceptance criteria when warranted. The projected life of the component, 

based on these calculations, is to be used to establish the interval between examinations. 

a) Corrosion Rate

It is recognized that for buried piping, most degradation mechanisms are not linear 

with time. Any corrosion rate calculated from one inspection is likely to have a large 

inaccuracy and could be either conservative (for inactive degradation mechanisms) or 

non-conservative (for recently activated mechanisms). Whenever possible, corrosion 
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rates should be determined by directly comparing measured wall thickness changes 

over a known time interval. Therefore, it is recommended to perform at least two 

inspections before a more accurate corrosion rate can be established.

When previous pipe wall thickness measurements or other data are not available, 

default external corrosion or pitting rate may be used to determine re-inspection 

intervals. NACE recommends a default external corrosion/pitting rate of 16 

mils/year. NACE further indicates that the default rate may be reduced by 24% (from 

16 mils/year), provided that the Cathodic Protection (CP) levels of the pipeline 

segments being evaluated have had at least 40 mV of polarization, considering the 

voltage drop, for a significant fraction of the time since installation. If the evaluated 

line can potentially be subjected to an internal corrosion process, such as Flow 

Accelerated Corrosion (FAC), Erosion/Corrosion (E/C) or Microbiologic Influenced 

Corrosion (MIC), effects of internal wall loss should also be simultaneously 

considered. 

For components with multiple examinations the corrosion rate may be more refined, 

as outlined in equation 1 below:

CR = (timemeas1 – timemeas2 ) x SF / time.......................Equation 1

Where:

CR = Corrosion rate, also referred to as Rml in Ref. 14

timemeas1 = tmeas at 1st examination

timemeas2 = tmeas at 2nd or subsequent examination at same 

location

tmeas = The minimum measured value

SF = Safety Factor (recommend at least 10%) = 1.10

time = The length of time between the (timemeas1 and timemeas2) 

examinations (years) 

b) Remaining Life (RL) Calculation

For the examination of a buried and underground pipe component or tank, the 

remaining life (RL) may be calculated as per Equation 2 below:

RL = (tmeas – tmin) / CR...........................................Equation 2

Where:

tmeas = The minimum measured value from the most recent examination

tmin = The minimum acceptable wall thickness for the current inspection 

required to meet Code requirements.

CR = Corrosion Rate (mils/year). Whenever possible external corrosion 

rates should be calculated from direct comparison of changes in wall thickness 

over time. However, for the initial examination the time period of active 

corrosion is unknown. In the absence of a known period of time from the 
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initiation of corrosion, a default corrosion rate (CR) of 16 mils/year may be 

used. 

If the evaluated line can be subjected to FAC, E/C, and/or MIC, then the 

effects of internal wall loss should be considered.

c) Time to Next Scheduled Inspection (NSI)

When tmeas is found to be less than or equal to 50% of tnom, the re-examination 

interval should be taken as one-half the remaining life (RL) calculated in 

Equation 2. The examination interval may be increased if it can be 

determined that the corrosion mechanism is inactive, for example a coating 

repair has been applied. When tmeas is greater than 50% of tnom, the reinspection interval may be taken as 75% of RL, as summarized below:

tmeas </= 0.5 x tnom: NSI = 0.50 x RL ..........................Equation 3

tmeas > 0.5 x tnom: NSI = 0.75 x RL...........................Equation 4

d) Mitigation or Engineering Technical Evaluation

i. A determination should be made to either mitigate directly or to perform 

additional engineering technical evaluation/analysis if the remaining life does 

not support the period of time until the pipe will be available for the next 

examination (e.g., refueling outage).

ii. If more than a single line is in the group, the lines with no examination data 

need to be evaluated based on the examinations performed for determination 

of condition. Additional examination may be required based on this 

evaluation. 

iii. A determination should be made to repair, replace or implement 

compensatory actions.

iv. All engineering evaluations should be performed and documented as required

by station procedures.
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7. Tanks

The number of buried and underground storage tanks (UST) is minimal compared to the volume 

of underground / buried piping. Therefore, a unique risk ranking process for these components 

will not be developed. Buried and underground storage tanks are regulated by several different 

federal, state and local agencies. For example to determine which agency regulates a specific 

tank you must look at its use, size and contents.

• Because of their importance to reactor safety, emergency diesel generator systems, 

including the diesel fuel storage and supply system and associated tanks (including both 

above and underground tanks) and piping are regulated by the NRC. However if these 

same tanks leak, the remedial investigation and clean up are regulated by the USEPA.

• If the UST contains a petroleum fuel, such as diesel or gasoline, and is not directly related 

to reactor safety, these tanks would be regulated by both the USEPA, State environmental 

agencies and the individual State Fire Marshals.

• If the UST contains hazardous wastes, then the tank system is regulated by the USEPA 

and State environmental agencies.

• If the UST contains a hazardous chemical, then the tank is regulated by the USEPA and 

the State environmental agencies along with the State Emergency Management Council 

(SEMA) and Local Emergency Planning Council (LEPC).

Credit should be taken for the inspection requirements required by the different federal, state and 

local regulation and different regulating agencies to determine the material condition 

requirements of the UST.
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8. References

1. “Recommendations for an Effective Program to Control the Degradation of Buried and 

Underground Piping and Tanks 1021175 (EPRI 1016456, Revision 1)

2. Radiological SSC Groundwater Initiative Risk Evaluation Criteria

3. A.P. Moser "Buried Pipe Design”, McGraw Hill, 2nd Edition (Table 2.7 “Live Loads”).

4. Section XI, Div. 1 Class 2 and 3 Metallic Piping Buried in a Back-Filled Trench, Inquiry, 

Draft “What Rules may be used to evaluate Class 2 and Class 3 metallic piping buried in 

a back-filled trench subjected to metal loss on the internal and external surfaces of the 

pipe or fitting”

5. ASME B&PV Code, Section XI

6. ASME B&PC Code, Section III

7. ASME B31.1, “Power Piping”

8. ASME Standard B31.3, “Process Piping”

9. ASME B31-G, “Manual for Determining the Remaining Strength of Corroded Pipelines”

10. American Petroleum Institute (API) Standard 510 Pressure Vessel Inspection Code: 

“Maintenance Inspection, Rating, Repair, and Alteration”

11. API Standard 570 Piping Inspection Code: “In-service Inspection, Rating, Repair, and 

Alteration of Piping Systems”

12. API Standard 653, “Tank Inspection, Repair, and Reconstruction”

13. ASME Code Case N-597-1, “Requirements for Analytical Evaluation of Pipe Wall 

Thinning”, Section XI Div. 1.

14. ASME Code Case N-513, “Evaluation Criteria for temporary Acceptance of Flaws in 

Moderate Energy Class 2 or 3 Piping”, Section XI, Div. 1.

15. API 579-2/ASME FFS-2, “Fitness-For-Service”

16. NACE Standard Practice SP0169-2007, Control of External Corrosion on Underground 

or Submerged Metallic Piping Systems, 2007. 

17. NACE International Standard Recommended Practice, RP0502, Item No. 21097, 

“Pipeline External Corrosion Direct Assessment Methodology”.

18. NUREG -1801, Rev. 2, Generic Aging Lessons Learned