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Summary of NRC HDPE Piping Confirmatory Research Activities

Summary of NRC HDPE Piping Confirmatory Research Activities. NESCC HDPE Piping Road Map Workshop April 18, 2013 Washington, D.C. Eric Focht, Materials Engineer U. S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research Division of Engineering Component Integrity Branch

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Summary of NRC HDPE Piping Confirmatory Research Activities

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  1. Summary of NRC HDPE Piping Confirmatory Research Activities NESCC HDPE Piping Road Map Workshop April 18, 2013 Washington, D.C. Eric Focht, Materials Engineer U. S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research Division of Engineering Component Integrity Branch eric.focht@nrc.gov

  2. RES: What We Do  Develop technical bases to support regulatory decisions • Technical tools, data, and analytical models • Confirmatory research and analyses  Provide in-house technical expertise to regulatory offices and the Regions  Anticipate NRC’s future needs • Develop technical infrastructure for advanced reactor licensing reviews • Support new reactor licensing • Develop Long-Term Research Plan

  3. NRC HDPE Piping Research2005-Present • Objectives: • Confirm the requirements proposed for the use of HDPE piping in safety-related applications (Code Cases N-755 & N-808, Code books) • Support NRC review of relief requests, topical reports, etc.. • Participate in ASME Code activities • Support MOU with EPRI • Confirmatory Research Projects: • Piping Integrity • NDE

  4. Supporting ASME Code Activities • B&PV Code participation • Attend Code Week • Currently, there are 12 groups covering HDPE piping (SC, SG, WG, SWG, TG) • ASME (& EPRI) sponsored workshops & forums: • ASME PE Piping Forums • 2009 and 2010 • ASME-EPRI HDPE Piping Workshop • 2010 and 2011 • Communicated NRC concerns and provided guidance for addressing the concerns.

  5. NRC HDPE Piping ResearchPiping Integrity: Allowable flaw size • Evaluate the slow crack growth resistance (SCG) of both the parent material and the fusion joint in the presence of a sharp flaw. • Data produced in industry sponsored research show that the parent materials may meet the requirements of N-755 but hoop stress does not fully characterize the driving force for SCG in the presence of a sharp flaw. • Evaluate data using fracture mechanics approach to describing the driving force. • Stress intensity factor, KI. • More accurately characterizes the driving force due to the presence of a sharp flaw. • Allowable flaw size for parent and fusion joints.

  6. NRC HDPE Piping ResearchNDE: Volumetric Inspection • Initial task evaluated various volumetric inspection technologies and compared the results (~2009-2011) • NUREG/CR-7136 • Follow-on project initiated in November 2011 at Pacific Northwest National Laboratory (PNNL). • Assess the capabilities, effectiveness, and reliability of nondestructive examination (NDE) methods and associated procedures, equipment, and personnel qualifications with respect to ASME initiatives • Tasks • Evaluate the effectiveness and reliability of current and state-of-the-art NDE methods to examine extruded products, fused joints, and fabricated configurations • Probe testing and modeling • Assess limitations of the methods • Evaluate probability of detection (POD) and uncertainty of characterization of flaws for each examination method • Evaluate Code Case flaw acceptance criteria

  7. Summary • NRC research is confirmatory and is not meant to resolve safety issues for the industry. • NRC research has identified concerns that are being addressed by ASME and EPRI. • NRC research level of effort has been curtailed due to availability of resources.

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  9. NRC HDPE Piping ResearchPiping Integrity: Allowable flaw size Effect of Temperature on Crack Growth Rate is Exponential 9

  10. NRC HDPE Piping ResearchPiping Integrity: Allowable flaw size • Data produced in industry sponsored research show that the resins may meet the requirements of N-755 but hoop stress does not fully characterize the driving force for SCG in the presence of a sharp flaw. Schematic of high temperature data shifted to the service temperature: Pipes with sharp flaws. Range of stresses for various pipe diameters and DR

  11. NRC HDPE Piping ResearchPiping Integrity: Allowable flaw size • Stress intensity, KI, more accurately characterizes the driving force due to the presence of a sharp flaw. The data may not support N-755 requirements for all pipe diameters and DRs. • Allowable flaw size is based on a percentage of the wall thickness. Schematic of high temperature data shifted to the service temperature: Pipes with sharp flaws Service life test data may not bound allowable service life conditions Range of applied KI based on hoop stress and allowable flaw size for various pipe diameters and DR

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