ML18142A468

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22 - NRC Cib Overview of Component Integrity Research Activities
ML18142A468
Person / Time
Issue date: 05/23/2018
From:
NRC/RES/DE
To:
Rezai A, NRR-DMLR 415-1328
References
Download: ML18142A468 (14)
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Overview of Component Integrity Research Activities Industry/NRC Materials Programs Technical Information Exchange May 23, 2018 Component Integrity Branch Division of Engineering Office of Nuclear Regulatory Research 1

1

Research Areas

  • Points of Contact

- Raj Iyengar, Branch Chief, Component Integrity Branch

- Robert Tregoning, Senior Level Advisor

  • Research Areas

- Reactor Pressure Vessel Integrity - Mark Kirk

- Piping Integrity Patrick Raynaud/Sara Lyons

- Probabilistic Fracture Mechanics - Patrick Raynaud/Matt Homiack

- Nondestructive Examination - Carol Nove

- Advanced Nonlight Water Reactors (ANLWR) - Raj Iyengar/Matt Gordon/Sara Lyons

- ASME Section XI Coordination & 50.55a Regulatory Guide Rulemaking - Michael Benson/Bruce Lin 2

2

RPV Integrity

  • Overview

- Objective:

  • Confirm the continued operating integrity of the RPV (including the SLR period)
  • Assess the accuracy of formulae that predict future embrittlement states for vessel materials

- Driver: User need from NRR; Assistance request from NRO; RAR from NRR for training; Support of RGGIB in periodic RG reviews (e.g., RG 1.99)

- Collaboration: JAEA, JNRA

  • Ongoing activities

- RPV Embrittlement

  • Assessment of shallow flaw effects on RPV integrity
  • Prediction of fluence beyond the beltline
  • REAP maintenance and addition of new surveillance data

- Codes & Standards: ASME Section XI; ASTM

- Finalization of PTS regulatory guide (RG 1.230) and technical basis document (NUREG 2163) 3 3

Accomplishment Highlight:

Late Blooming Phases

  • Possible Concern: Possible rapid embrittlement in lowcopper steels with high nickel & manganese. Mechanism not accounted for by USNRC predictions.
  • RES Review: Comprehensive literature review & surveillance data assessment demonstrate LBPs are not of concern for US RPVs.

- Level of Ni > 1% postulated for LBP occurrence

- Steel alloys / conditions of possible concern largely absent from USA fleet

- Evidence of delayed accelerated embrittlement is lacking

  • Current Status: Ongoing research (DOE, intl.) to better understand LBPs. New data suggests no sudden late embrittlement and much smaller T values for USA steels.

08/15/2017 RPV Integrity l RES FO Brief 4 4

RPV Integrity Accomplishments and Path Forward

  • Accomplishments

- TLR on RPV fluence evaluation methodology for beyond the active core region

- Independent review of NuScale Power Pressure and Temperature Limits (PTL) Methodology report for NRO

  • Path Forward

- Support NRO for NuScale application review

- Continue codes and standards support (ASTM E10; ASME CC N830 revision) 5 5

Piping Integrity

  • Overview

- Objective: Develop/Enhance analytical methods and tools to assess structural integrity of reactor piping systems

- Driver: NRR User Need Request

- Collaboration: EPRI, NEA/CSNI

  • Ongoing activities

- Development of modeling guidelines for assessment of weld residual stress (WRS) effects in assessment of component integrity

- Assessment of research and industry experience in peening of reactor components

- Participation in ASME Boiler and Pressure Vessel Code,Section XI

- Coordination of ASME BPV Code Case Regulatory Guides to incorporate by reference into 10 CFR 50.55a

- Evaluation of Extended Finite Element Method (xFEM) for applicability in crack growth (PWSCC) analyses 6

Ongoing Activity:

Applying xFEM Techniques to PWSCC Growth

  • Application of Extended Finite Element Method (xFEM) to predict PWSCC crack growth in 3D component geometries.
  • Conventional FEM:

- Uses idealized crack shape and growth model (semielliptical)

- Assumes planar (2D) crack growth

- Uses 2D WRS profile for crack growth which is path dependent and user defined

  • xFEM:

- Meshindependent analysis of flaws

- SIF calculation of multiple cracks shapes without major changes to model

- 3D crack growth without remeshing

  • Participation in international effort on benchmarking of xFEM capabilities.

(OECDCSNI) 7

Piping Integrity Accomplishments and Path Forward

  • Accomplishments

- Draft NUREG on WRS validation

- Section XI Standards Committee and Executive Committee participation

- Issued draft Regulatory Guides for ASME Code Cases, 20092013 and 2015 editions to incorporate by reference into 10 CFR 50.55a

  • Path Forward

- Issue final reports on WRS validation

- Develop and implement research plan for validation xFEMA analysis for PWSCC predictions

- Continue ASME Section XI engagement

- Prepare draft Regulatory Guides for ASME Code Cases for 2017 Edition of the Boiler and Pressure Vessel Code 8

8

Probabilistic Component Integrity

  • Overview

- Objective: Develop probabilistic methods to ensure structural integrity of piping systems

- Driver: NRR User Need Request

- Collaboration: EPRI, JNRA, JAEA, SSM, CNSC

  • Ongoing activities

- Support NRR in the acceptance and application of xLPR v2

- Development of Probabilistic Fracture Mechanics Regulatory Guide

- Continue effort on V&V of FAVOR code, maintenance, applications, development, and modernization 9

9

Probabilistic Component Integrity Accomplishments and Path Forward

  • Accomplishments

- xLPR verification and validation testing

- xLPR code theory and handson training provided to NRC staff

- xLPR PWSCC initiation model parameter development, confirmatory analyses, and validation

- Completed draft report on Increasing Confidence in PFM Analyses

- Initiated work on FAVOR V&V, maintenance, and applications

  • Path Forward

- Support NRR regulatory acceptability review for xLPR

- Complete efforts to ensure public release of xLPR

- Initiate studies on leakbeforebreak applications with xLPR

- Develop PFM Draft Regulatory Guide, with NUREG technical basis document and PFM pilot studies to test guidance

- Bring FAVOR up to modern standards, adapt FAVOR to solve evolving reactor pressure vessel issues 10 10

Non-Destructive Examination

  • Overview

- Objective: Evaluate effectiveness and reliability of NDE techniques

- Driver: NRR User Need Request

- Collaboration: EPRI, DOE, International

  • Ongoing activities

- Completion of comprehensive summary of NDE research on CASS and assessment of stateoftheart in inspecting welds in CASS materials

- Assessment of industrys CASS round robin (rigorous, statistically based)

- Provide technical basis for conducting, interpreting, and applying the results of ultrasonic testing (UT) Modeling

- Assess the effects of incomplete examination coverage

- Assessment of human factors issues in NDE

- Support codes & standards activities (ASME - Section XI)

- Assessment of inspection systems for storage casks 11 11

ANLWR Materials and Component Integrity

  • Overview

- Objective: Assess the performance needs and issues for structural materials to be used in advanced nonLWRs (ANLWRs); Support the development of a regulatory framework for materialsrelated issues for ANLWRs

- Driver: NRC Vision and Strategy on ANLWRs

  • Strategy 2: Acquire/develop sufficient computer codes and tools to perform nonLWR regulatory reviews
  • Strategy 4: Facilitate industry codes and standards needed to support the nonLWR life cycle
  • Ongoing activities

- Identification of regulatory gaps for sodium fast reactors and molten salt reactors, building on the past efforts for hightemperature gas reactors

- Assessment of materials/component integrity issues for molten salt reactors (MSR)

- Operational experience compendia for materials/component integrity issues for sodium fast reactors (SFR) and hightemperature gas reactors (HTGR)

- Participation in ASME Codes and Standards Sections III and XI activities 12 12

ANLWR Materials Accomplishments

  • Technical gap assessment for materials/component integrity for molten salt reactors - ORNL Draft report summary:
  • Limited high-temperature creep data at the highest possible core outlet temperatures
  • Limited data on salt purity effects on coolant compatibility and performance
  • Limited data and mechanistic understanding on irradiation degradation effects
  • Operational experience compendia for sodium fast reactors (SFRs) and high-temperature gas reactors (HTGR) - EWC-Commercial Over 100 OpE sources have been identified and reviewed for SFRs

[Phenix, SuperPhenix, FFTF, EBR-II] and HTGRs [Fort St Vrain, Peach Bottom, AVR and THTR-300]

  • Weld design and quality are critical for SFRs
  • Design flaws seem to dominate HTGRs, resulting in unexpectedly high temperatures, moisture and oxygen ingress, and trapped pebbles Separate bilateral engagements with Office of Nuclear Regulation, UK; IRSN- France; and JAEA and JNRZ - Japan 13 13

ANLWR Materials Accomplishments and Path Forward

  • Support knowledge and data enhancement of environmental effects on reactor components (internals, piping, welds, coatings) at high temperatures. (corrosion, radiation effects)
  • Develop/Enhance computational codes for component integrity applicable to ANLWRs
  • Explore opportunities to obtain information, data, and assessment tools through domestic and international collaboration
  • Conduct research activities to develop technical bases to resolve major materials related issues 14 14
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