ML20248H554
| ML20248H554 | |
| Person / Time | |
|---|---|
| Issue date: | 09/16/2020 |
| From: | Louise Lund NRC/RES/DE |
| To: | Anna Bradford NRC/NRR/DNRL |
| Carol Nove | |
| Shared Package | |
| ML20248H553 | List: |
| References | |
| UNR NRR- 2013-009 | |
| Download: ML20248H554 (3) | |
Text
September
. 16, 2020 MEMORANDUM TO: Anna Bradford, Director Division of New and Renewed Licenses Office of Nuclear Reactor Regulation Bowen, Jeremy signing on behalf FROM: Louise Lund, Director of Lund, Louise on 09/16/20 Division of Engineering Office of Nuclear Regulatory Research
SUBJECT:
IMPENDING PUBLICATION OF TECHNICAL LETTER REPORT ENTITLED EVALUATING FLAW DETECTABILITY UNDER LIMITED-COVERAGE CONDITIONS (PNNL-30238)
(UNR NRR- 2013-009)
The Office of Nuclear Regulatory Research (RES) has completed a technical letter report entitled Evaluating Flaw Detectability under Limited-Coverage Conditions, (ADAMS Accession ML20248H555) under contract with Pacific Northwest National Laboratory (PNNL). This Technical Letter Report (TLR) documents work performed under User Need Requests (UNR)
NRR-2013-009 Evaluating the Reliability of Nondestructive Examinations of Vessels and Piping and NRR-2020-002, Update of the User Need Request for Evaluating the Reliability of Nondestructive Examinations of Vessels and Piping. These UNRs focus on assessing the reliability and effectiveness of nondestructive examination methods used in nuclear power plants. Both UNRs include the task Effects of Missed Volumetric Coverage requesting RES determine the effects of missed coverage on flaw probability of detection (POD).
The work documented in this TLR is part of a two-phase effort at PNNL, under Task 2 of NRR-2020-002 to assess the ability of ultrasonic examination to detect flaws when part of a weld is un-inspectable due to limited-coverage conditions. Limited-coverage conditions are a widespread problem that exist in all nuclear power plants, i.e., there are conditions that limit scanning the entire required examination volume or prevent adequate probe coupling in certain areas. If greater than 90% of the required examination volume cannot be obtained, licensees are required to submit a request for relief. The work leverages modeling and simulation capabilities being developed under Task 1 of NRR-2020-002, experimental measurements, and blind testing (e.g., round-robin testing) to better understand the impact on inspection reliability with varying amounts of the flaws hidden from inspection. Empirical and theoretical assessments are being conducted to develop a technical foundation that can be used to assist the staff in the process of reviewing licensee requests for relief related to limited-coverage conditions.
CONTACT: Carol Nove, RES/DE/CIB (301) 415-2217 The current work, focused on assessing the impacts of weld crowns and surface conditions that
A. Bradford 2 constrain probe movement in either the axial or circumferential scan axes, was targeted at developing an effective data acquisition, analysis and evaluation process. By using materials that were essentially non-attenuative to ultrasonic sound energy and machined reflectors, PNNL was able to assess flaw detectability using more simplistic scenarios under basic limited-coverage conditions. Understanding the impact of specific limiting factors on detection probability for basic piping weld/material configurations lays the groundwork for the next phase of the study that will assess the full complement of more realistic and challenging limited-coverage conditions. The next phase will include thermal fatigue cracks, rather than machined reflectors, and components with dissimilar metal welds and attenuative base materials (such as CASS).
Staff representatives from the Division of New and Renewed Licenses in the Office of Nuclear Reactor Regulation (NRR) reviewed a draft of this TLR. The Staff agreed with the key findings and conclusions of the report, and stated, the TLR is of high quality and is a good interim report on the research. The TLR contains sufficient detail and rigor to be used as a reference in evaluating relief requests under 10 CFR50.55a(g)(5)(iii).
RES has established an online quality survey to collect feedback from user offices on the usefulness of RES products and services. This survey can be found online at the hyperlink: RES Quality Survey. I would appreciate the responsible manager or supervisor completing this short survey within the next 10 working days to present your offices views of the delivered RES product.
If additional information is required, or there are any concerns with the impending public release of this TLR, please contact Carol A. Nove of my staff at 301-415-2217 or can2@nrc.gov.
Enclosure:
As stated
ML20248H553; ML20248H555 OFFICE RES/DE/CIB RES/DE/CIB RES/DE LLund NAME CNove CN RIyengar RI JBowen for JB DATE Sep 9, 2020 Sep 10, 2020 Sep 16, 2020