Session: CS-14-01: Repair, Replacement and Mitigation for Fitness-for-Service Rules

Paper Number: 84425

84425 - Use of HDPE Piping in Buried Nuclear Class 3 Systems Categorized as Low Safety Significant 

10CFR50.69 and ASME Code Case N-752 include provisions for using PRA analysis to categorize systems or portions of piping systems as Low Safety Significant (LSS) which may then be legally exempted from the administrative and technical special treatment requirements imposed by the Regulator and the ASME Nuclear Codes.  Instead, Owners establish alternative treatment requirements, enabling such items to be designed, procured, maintained, repaired, replaced, examined, and tested essentially the same as balance-of-plant items – while maintaining reasonable confidence that each LSS item remains capable of performing its safety-related function(s) under design basis conditions. 

Code Case N-755 and subsequently ASME Section III Appendix XXVI were developed by ASME and approved by the Regulator for providing deterministic rules for new construction of, or replacement of existing, Class 3 buried piping using High Density Polyethylene (HDPE) piping. These rules contain many special treatment requirements that have basically put HDPE out of economic contention with replacement of degraded buried Class 3 pipe using thicker-walled carbon steel piping, low alloy piping, or even AL6XN.  Re-evaluation of buried portions of Class 3 service water and cooling water piping using the risk-informed provisions of 10CFR50.69 and Code Case N-752 should result in recategorization of most buried Class 3 service water piping as Low Safety Significant, enabling relaxation of many of those special treatment requirements.

As a result, the ASME Code Section XI Repair/Replacement committees are developing a Code Case that will apply ASME Section III Appendix XXVI for the replacement of Class 3 buried piping categorized as Low Safety Significant while exempting the design and construction from the special treatment requirements of Section III Appendix XXVI.  This Code Case will provide ASME Code Committee guidance for material procurement, design, fabrication, installation, and testing of technically superior HDPE piping as a cost competitive permanent replacement for degraded buried safety related Class 3 carbon steel piping.  This paper will provide the background, technical bases, practicality, purpose, content, and the benefits for nuclear plant Owners who implement the Code Case for Use of HDPE Piping in Buried Nuclear Class 3 Systems Categorized as Low Safety Significant.

Presenting Author: Jim O'Sullivan Procon 1, LLC

Presenting Author Biography: Jim earned his Bachelor of Science degree in Mechanical Engineering at Santa Clara University, California. He is a Registered Professional Engineer in the State of California and has accumulated more than 40 years of experience in nuclear plant design, construction, operation, maintenance, and repair. This began with 23 years in design, field engineering, and construction management with Bechtel including initial construction of the Limerick Generating Station and throughout the entire construction and startup of the Susquehanna Steam Electric Station. This evolved into 16 additional years in welding &amp; Code engineering, field engineering and planning supervision, Boiling Water Reactor Senior Reactor Certification, plant site design engineering supervision, plant site modification group management, and nuclear modification department management with Pennsylvania Power and Light for their Susquehanna nuclear plant. Jim has spent the subsequent 19 years as a nuclear welding, fusing and Code engineering consultant, nuclear plant welding engineering supplemental outage support, research and development, engineering training, technical program development, and technical writing with his own company Procon1, LLC. <br/>Jim has been closely involved in the development of various industry codes and standards including AWS D3.6 Underwater Welding Code; Boiler and Pressure Vessel Codes ASME Section XI Subsection IWA Repair/ Replacement Activities, Section IX Part QF Plastic Fusing, Section III Appendix XXVI Rules for Construction of Buried Polyethylene Pressure Piping, and various ASME Section III and Section XI Code Cases associated with metallic and non-metallic repair/ replacement of nuclear components. He has authored numerous published technical papers and nuclear industry reports and guidelines. He has been a member of ASME Code Committees for over 30 years and was recipient of the 1989 American Nuclear Society Award for Meritorious Performance in Reactor Operations and the ASME 2019 BPV Section XI Outstanding Service Award.

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