ML18331A094
| ML18331A094 | |
| Person / Time | |
|---|---|
| Issue date: | 11/28/2018 |
| From: | Bernard Thomas NRC/RES/DE |
| To: | George Wilson Division of Materials and License Renewal |
| Carol Nove | |
| Shared Package | |
| ML18331A093 | List: |
| References | |
| Download: ML18331A094 (3) | |
Text
November 28, 2018 MEMORANDUM TO: George A. Wilson, Director Division of Materials and License Renewal Office of Nuclear Reactor Regulation FROM: Brian E. Thomas, Director /RA Ronaldo Jenkins Acting for/
Division of Engineering Office of Nuclear Regulatory Research
SUBJECT:
IMPENDING PUBLICATION OF TECHNICAL LETTER REPORT, PNNL-27712, ENTITLED INTERIM ANALYSIS OF THE EPRI CASS ROUND ROBIN STUDY The Office of Nuclear Regulatory Research (RES) has completed Pacific Northwest National Laboratory (PNNL) - 27712, Technical Letter Report (TLR) entitled Interim Analysis of the Electric Power Research Institute (EPRI) Cast Austenitic Stainless Steel (CASS) Round Robin Study, (ADAMS Accession ML18219B319). This report documents work performed under Task 5, Detection and Characterization of Flaws in User Need Request (UNR) NRR-2013-009, Evaluating the Reliability of Nondestructive Examinations of Vessels and Piping. This UNR focuses on assessing the reliability and effectiveness of nondestructive examination (NDE) methods used in nuclear power plants. Specifically, Task 5 assesses the ability of NDE techniques to detect and characterize flaws located at various through-wall depths in configurations and weldments common to the nuclear industry.
The attached TLR documents Pacific Northwest National Laboratory (PNNLs) independent assessment of the CASS Round Robin Study (RRS) conducted by the EPRI to evaluate the detection performance of state-of-the-art ultrasonic methods applied to CASS weldments. The RRS provides important insights that will be used in the development of performance demonstration requirements in American Society of Mechanical Engineers Code,Section XI, Appendix VIII, Supplement 9, Qualification Requirements for Cast Austenitic Piping Welds (Supplement 9). This TLR is the first of two TLRs on the PNNL analysis of the RRS. As of this date, EPRI continues to maintain the security of the mockups used for the RRS so that further blind studies may be conducted. As such, this first interim TLR is intended to provide NRR with a summary of PNNLs analysis results until such time as it is possible to divulge detailed information on the mockups and examination methods applied.
PNNLs analysis methods differed from EPRIs in that each organization applied their unique perspective to the data analysis. PNNL relied on their extensive experience in analyzing results from previous NDE round robin studies, and EPRI approached the analysis from a performance demonstration initiative perspective. In doing so, PNNLs focus was on detectability of flaw signals in the difficult to examine, course-grained CASS, and EPRI focused on flaw characterization (length- and depth-sizing).
CONTACT: Carol A. Nove, RES/DE/CIB (301) 415-2217
G. Wilson The key conclusion of PNNLs analysis was that flaw detection in CASS materials is possible with a high degree of confidence and a low probability of false calls when the most appropriate, currently available techniques are used. In particular, this means using low-frequency, phased-array probes for examining thick walled CASS piping welds.
Supplement 9 has been in the course of preparation since Appendix VIII was initially established. While significant progress has been made in developing methods to inspect CASS weldments, the qualification requirements have not yet been established. However, in the final Edition/Addenda rulemaking published on 7/18/17 (82 FR32934), the NRC added paragraph
§ 50.55a(g)(6)(ii)(F)(11) to address examination requirements through cast stainless steel materials by requiring the use of Appendix VIII qualifications to meet the inspection requirements of Paragraph -2500(a) of ASME BPV Code Case N-770-2 by January 1, 2022.
Thus, the staff will use the results of PNNLs analysis of the CASS RRS to inform their assessment of industrys development of all the facets of Supplement 9 requirements and the associated performance demonstration initiative qualification program.
Staff representatives from the Division of Materials and License Renewal in NRR reviewed a draft of this TLR, and the enclosed final TLR reflects the resolution of their comments.
Nonetheless, please feel free to notify the responsible RES contact if you have any questions concerning the impending public release of this TLR.
If additional information is required, please contact Carol A. Nove of my staff at 301-415-2217 or can2@nrc.gov.
Enclosure:
As stated
G. Wilson
SUBJECT:
IMPENDING PUBLICATION OF TECHNICAL LETTER REPORT, PNNL-27712, ENTITLED INTERIM ANALYSIS OF THE EPRI CASS ROUND ROBIN STUDY DISTRIBUTION:
S. Ruffin, NRR S. Cumblidge, NRR D. Rudland, NRR B. Lin, RES L. Smith, RES J. Honcharik, NRO E. Reichelt, NRO ADAMS Package Accession No.: ML18331A093 OFFICE RES/DE/CIB RES/DE/CIB D:RES/DE NAME C. Nove R. Iyengar JK for B. Thomas DATE 11/27/2018 11/28/2018 11/28/2018 OFFICIAL RECORD COPY