United States Nuclear Regulatory Commission - Protecting People and the Environment

Buried Piping Activities

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Background

Nuclear power plants have extensive piping systems. Some of these pipes are buried. Cooling water is the most common material transported in buried pipe. Cooling water is generally taken from a lake or river and, except for a slight increase in temperature, is returned unchanged to the same body of water. Generally, this water contains only naturally occurring, background, levels of radioactive materials. Some buried piping also transports smaller amounts of water that may contain slightly elevated levels of radioactive isotopes, most commonly tritium. A few buried pipes may contain materials other than water. Diesel fuel is the most significant of these materials.

The NRC defines buried piping as piping which is in contact with soil. The NRC recognizes that other structures and components exist in nuclear power plants which are beneath the surface of the earth but do not meet the definition of buried piping and are not included in the NRC's buried piping activities. These other structures and components include piping enclosed in trenches or vaults. The NRC distinguishes between buried piping and other structures and components beneath the surface of the earth because they are exposed to different environments, they corrode by different mechanisms, and they are protected from corrosion differently.

At nuclear power plants, the buried piping systems are comparable to those used in other industries such as public water supply and oil and gas transmission. Preventative measures are taken for piping which may corrode, such as coating piping with corrosion resistant material. While buried piping is normally reliable, damage to the corrosion resistant coatings can lead to small leaks.

As a result of this type of corrosion, several leaks in buried pipes have occurred recently. These leaks have not created safety hazards at the plants because, in spite of the leak, the pipe was still carrying more than enough water to cool the plant. While some of these leaks did introduce slightly elevated levels of radiation into the ground water, they did not result in the exposure of any member of the public or power plant employee to radiation beyond regulatory limits.

While these incidents have not jeopardized public health and safety, the NRC and the nuclear power industry as a whole are reexamining the issue of buried piping to determine whether any changes are required in the current approach to the design, maintenance, and inspection of buried piping. Current NRC activities and some industry activities are described in the linked documents below. The NRC anticipates that, in the short term, the increase in excavation and inspection could increase the frequency of discovery of degraded buried piping.

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Related Documents

Date Description
  Groundwater Protection
02/04/2016 Issuance of Final License Renewal Interim Staff Guidance (LR-ISG), LR-ISG-2015-01, "Changes to Buried and Underground Piping and Tank Recommendations"
05/05/2015 Issuance of Draft License Renewal Interim Staff Guidance (LR-ISG), LR-ISG-2015-01, "Changes to Buried and Underground Piping and Tank Recommendations"
April 2013 NEI 09-14 Rev. 3, Guideline for the Management of Underground Piping and Tank Integrity
05/01/2013 Issuance of Rev. 3 to NEI 09-14, Guideline for the Management of Buried Piping Integrity
04/17/2013 NRR Action Plan, Buried Piping, Revision 3
11/2012 NEI 09-14 Rev. 2, Guideline for the Management of Underground Piping and Tank Integrity
11/21/2012 Issuance of Rev. 2 to NEI 09-14, Guideline for the Management of Buried Piping Integrity
06/13/2012 Staff Requirements Memorandum "Proposed Changes to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Associated with Buried Piping", SRM-SECY-12-0060
04/17/2012 Commission Paper "Proposed Changes to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Associated with Buried Piping", SECY-12-0060
05/24/2012 Staff Requirements Memorandum "Options for Revising the Regulatory Approach to Ground Water Protection" SRM-SECY-12-0046
05/14/2012 Buried Pipe Temporary Instruction Phase 2 Requirements
03/29/2012 Commission Paper "Options for Revising the Regulatory Approach to Ground Water Protection", SECY-12-0046
11/30/2011 NRR Action Plan, Buried Piping, Revision 2
08/18/2011 NEI Acknowledgment of Receipt of Information Related to Buried and Underground Piping
06/2011 GAO - Report to Congressional Requesters – "Oversight of Underground Piping Systems Commensurate with Risk, but Proactive Measures Could Help Address Future Leaks"
05/17/2011

Response to Request for Underground Piping Information

03/23/2011 Committee Letter Report– Status of Groundwater Protection Task Force Efforts
04/2011 Industry Guidance for the Development of Inspection Plans for Buried Piping
03/07/2011 Underground Piping and Tanks Integrity Initiative
01/2011 Underground Piping and Tanks Initiative Semi-Annual Report
12/2010 NEI 09-14 Rev. 1, Guideline for the Management of Underground Piping and Tank Integrity
11/03/2010 NEI 09-14 (Rev 0),Guideline for the Management of Buried Piping Integrity
09/27/2010 Industry Initiative on Underground Piping and Tanks Integrity
09/14/2010 NRR Action Plan, Buried Piping, Revision 1
08/18/2010 NRC Letter to NEI requesting information concerning the Buried Piping Integrity Initiative
12/02/2009 SECY-09-0174 - Staff Progress In Evaluation of Buried Piping At Nuclear Reactor Facilities
11/18/2009

Proposed Buried Piping Integrity Initiative

10/22/2009

November 20, 2009, Letter Forwarding Industry Initiative on Buried Piping Integrity

09/03/2009

Chairman's Tasking to Staff Regarding Evaluation of Buried Piping at Nuclear Reactor Facilities

06/2005 Risk-Informed Assessment of Degradation Buried Piping Systems in Nuclear Power Plants (NUREG/CR-6876)

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Public Meetings

Date Description
09/20/2016

Meeting between the NRC and Industry Representatives to Discuss Buried Piping Issues

01/21/2015

Meeting between the NRC and Industry Representatives to Discuss Buried Piping Issues

06/11/2014

Meeting between the NRC and Industry Representatives to Discuss Buried Piping Issues

10/09/2013

Meeting between the NRC and Industry Representatives to Discuss Buried Piping Issues

04/25/2013

Meeting between the NRC and Industry Representatives to Discuss Buried Piping Issues

12/05/2012

Meeting between the NRC and Industry Representatives to Discuss Buried Piping Issues

04/04/2012

Meeting between the NRC and Industry Representatives to Discuss Buried Piping Issues

10/20/2011

Meeting Between the NRC and Industry Representatives to Discuss the Industry's Buried Piping Integrity Initiative

03/30/2011

Meeting Between the NRC and Industry Representatives To Discuss The Industry's Buried Piping Integrity Initiative

09/21/2010

Meeting Between the NRC and Industry Representatives To Discuss The Industry's Buried Piping Integrity Initiative

02/24/2010

Meeting Between the NRC and Industry Representatives To Discuss The Industry's Buried Piping Integrity Initiative

10/22/2009

Meeting Between the NRC and Industry Representatives to Discuss Buried Piping Issues

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Page Last Reviewed/Updated Monday, October 24, 2016