ML13282A382

10/2/2013 Summary of Pre-Application Meeting with Pacific Gas and Electric Company to Discuss Upcoming Structural Weld Overlay Relief Request to Use an Alternative to Disposition Detected Laminar Indications at Diablo Canyon, Unit 2

ML13282A382
Person / Time
Site:	Diablo Canyon
Issue date:	11/07/2013
From:	Jennivine Rankin Plant Licensing Branch IV
To:	Pacific Gas & Electric Co
Rankin J
References
TAC MF2675
Download: ML13282A382 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 7, 2013 LICENSEE: Pacific Gas and Electric Company FACILITY: Diablo Canyon Power Plant, Unit No. 2

SUMMARY

OF OCTOBER 2, 2013, PRE-SUBMITTAL MEETING WITH PACIFIC GAS AND ELECTRIC COMPANY TO DISCUSS A REQUEST TO USE AN ALTERNATIVE TO DISPOSITION DETECTED LAMINAR INDICATIONS ON PRESSURIZER SAFETY NOZZLES (TAC NO .. MF2675)

On October 2, 2013, a Category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Pacific Gas and Electric Company (PG&E, the licensee) at NRC Headquarters, One White Flint North, 11555 Rockville Pike, Rockville, Maryland. The purpose of the meeting was to discuss PG&E's plans to submit a request to use an alternative to disposition detected laminar indications on overlaid dissimilar metal welds (structural weld overlays (SWOL)) at pressurizer nozzles at Diablo Canyon Power Plant, Unit No.2 (DCPP). The meeting notice and agenda are publicly available in the Agencywide Documents Access and Management System (ADAMS) at Accession No. ML13260A005. The licensee's meeting slide presentation is available at ADAMS Accession No. ML13274A514. A list of attendees is provided in the Enclosure.

PG&E indicated that the proposed relief request would be similar to Relief Request REP-1 U2, dated March 5, 2013 (ADAMS Accession No. ML130780374). By letter dated August 28, 2013, the NRC staff authorized the use of Relief Request REP-1 U2, Revision 2, at DCPP, for the fuel cycle following the 2013 refueling outage, 2R17 (ADAMS Accession No. ML13232A308). In the safety evaluation dated August 28, 2013, the NRC staff had two concerns regarding authorization of continued relief. First, the NRC staff had concerns associated with the reasons the qualified conventional ultrasonic test (UT) conducted did not detect the laminar indications and assurances that the phased array (PA) technique found all unacceptable flaws. Secondly, the NRC staff had concerns on the impact of the laminar indications on the structural integrity of the overlaid welds.

PG&E described its root cause evaluation process, findings, conclusions, and corrective actions with respect to its ultrasonic examinations of the overlaid dissimilar metal welds at the pressurizer nozzles performed in spring 2013. The licensee concluded that while there was no statistical advantage between manual conventional UT and manual PA methods during qualification and that the manual conventional UT was able to detect the flaws in Safety Nozzles A and B, human factors related to scanning speed and probe design were identified as issues in the failed examinations. PG&E will thus employ the PA technique for subsequent examinations of the overlaid dissimilar metal welds at the pressurizer nozzles. In addition, PG&E described its flaw evaluations, including key elements of the flaw analysis modeling and analytical approach to address the NRC concerns of structural integrity of the welds. PG&E indicated it would be submitting the relief request in March 2014 and requesting approval by July 2014. This is to support the upcoming Unit 2 refueling outage commencing October 2014.

During the meeting on October 2, 2013, the NRC suggested that PG&E consider the following during preparation of the relief request:

• Include the PA procedure number that will be used for subsequent examinations of the overlaid dissimilar metal welds at pressurizer nozzles.

• Include a description of the corrective actions taken by PG&E as a result of the root cause investigation to ensure adequacy and reliability of subsequent examinations.

• Include the root cause analysis in the relief request or adequate portions of the root cause analysis to support the conclusions that UT and PA methods can detect unacceptable flaws, including the use of the human error investigation tool.

• Describe and/or define acceptance criteria for indications and/or crack growth from repeatability of inspections.

• Include a description of the inspection history and chronology of the dissimilar metal welds and associated SWOLs at the pressurizer nozzles.

• Identify the particular sections and subarticles of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) from which relief is requested.

• Ensure that the relief request is clear that subsequent inspections will re-examine the previously detected flaws even though they are outside the inservice inspection examination area.

• It is preferred that the relief request is based on paragraph 50.55a(a)(3)(ii) of Title 10 of the Code of Federal Regulations on the basis that the complying with the specified ASME Code requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

• State clearly the duration of the proposed alternative.

No Public Meeting Feedback Forms were received for this meeting.

Please direct any inquiries to me at 301-415-1530 or at Jennivine. Rankin@nrc.gov.

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Jennie K. Rankin, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-323

Enclosure:

List of Attendees cc w/encl: Distribution via Listserv

LIST OF ATTENDEES OCTOBER 2. 2013. MEETING WITH PACIFIC GAS AND ELECTRIC COMPANY REGARDING DIABLO CANYON POWER PLANT. UNIT NO.2 ALTERNATIVE TO DISPOSITION DETECTED LAMINAR INDICATIONS DOCKET NO. 50-323 NAME ORGANIZATION Philippe Soenen Pacific Gas and Electric Jeff Summy Pacific Gas and Electric Rama Thatipamala Pacific Gas and Electric Michael Leger Pacific Gas and Electric David Gonzalez Pacific Gas and Electric Russ Cipolla

• Pacific Gas and Electric Suresh Khatri

• Pacific Gas and Electric William Farrell** AREVA Tim Wiger *** AREVA Astok Nana *** AREVA Jeff Fleck *** AREVA Stephen Cumblidge U.S. Nuclear Regulatory Commission John Tsao U.S. Nuclear Regulatory Commission Jay Collins U.S. Nuclear Regulatory Commission John Honcharik U.S. Nuclear Regulatory Commission Jennie Rankin U.S. Nuclear Regulatory Commission Kyle Hanley U.S. Nuclear Regulatory Commission Steve Vitto U.S. Nuclear Regulatory Commission Carol Nove U.S. Nuclear Regulatory Commission Tim Lupoid U.S. Nuclear Regulatory Commission Ned Finney* Structural Integrity Associates, Inc.

John Hayden

• Structural Integrity Associates, Inc.

Mike Turnbow

• Public

• participated via telephone

• • participated via telephone and represented PG&E

• • • represented PG&E Enclosure

Meeting Notice ML13260A005; Meeting Summary ML13282A382; Slides ML13274A514 *via email OFFICE NRR/DORULPL4/PM NRR/DORU/LPL4/LA NRR/DE/EPNB* NRR/DE/EPNB*

NAME JRankin JBurkhardt JTsao SCumblidge DATE 10/30/13 10/30/13 10/8/13 10/8/13 OFFICE NRR/DORULPL4/BC NRR/DORULPL4/PM NAME MMarkley JRankin DATE 11/7113 11/7113