ML080090154

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Summary of Conference Call Held with PWR Licensees on the Temporary License Amendment Needed for Steam Generator Tube Inspections in Spring 2008 Refueling Outages
ML080090154
Person / Time
Site: Wolf Creek Wolf Creek Nuclear Operating Corporation icon.png
Issue date: 01/22/2008
From: Donohew J
NRC/NRR/ADRO/DORL/LPLIV
To: Hiltz T
NRC/NRR/ADRO/DORL/LPLIV
Donohew J N, NRR/DORL/LPL4, 415-1307
References
ET 06-0004, TAC MD7762
Download: ML080090154 (7)


Text

January 22, 2008 MEMORANDUM TO: Thomas G. Hiltz, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM: Jack N. Donohew, Senior Project Manager /RA/

Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

WOLF CREEK GENERATING STATION -

SUMMARY

OF CONFERENCE CALL HELD WITH PWR LICENSEES ON THE NEW TEMPORARY LICENSE AMENDMENT NEEDED FOR STEAM GENERATOR TUBE INSPECTIONS IN SPRING 2008 REFUELING OUTAGES (TAC NO. MD7762)

The NRC staff has been reviewing the license amendment request (LAR), for the Wolf Creek Generating Station (WCGS), submitted by letter dated February 21, 2006 (ET 06-0004)

(Agencywide Documents Access and Management System (ADAMS) Accession No. ML060600456). In this review, Wolf Creek Nuclear Operating Corporation, the licensee for Wolf Creek Generating Station, (the licensee) has submitted two supplemental letters providing responses to NRC questions and we have conducted three meetings with the licensee, including the closed meeting held at the Westinghouse office on December 13, 2007.

Following the December 13, 2007, meeting with the licensee, the SG [Steam Generator] Tube Integrity and Chemical Engineering Branch (CSGB), which is reviewing the WCGS application, stated that it was not prepared to approve the Westinghouse methodology that is being used by the licensee to justify its LAR. Therefore, pressurized-water reactor (PWR) licensees, like the licensee, will need to consider submitting LARs to cover SG inspections in the upcoming spring 2008 refueling outages if they want to limit the inspection and repair of steam generator (SG) tubes in the upcoming spring 2008 refueling outages. Without such LARs, the plant Technical Specifications (TSs) require the inspection of the entire tube in the tubesheet and repair by the repair criteria stated in the TSs. Licensees have previously had one-cycle amendments approved that did not require inspections of the portion of the SG tubes more than 17 inches below the top of the tubesheet. These new temporary LARs could not be the same one-cycle LARs that have been approved for PWR licensees in the past few years because they could not rely on the justification that submitted and approved by the NRC staff in these amendments.

A call was held with the licensee on December 21, 2007, since it had submitted the LAR that was under review by the NRC staff. A further call was held on January 3, 2008, that was a followup to the December 21, 2007, call with only the licensee and included other PWR licensees that may be affected by the NRC staff decision to have this temporary LAR for the spring 2008 outages because these licensees may submit new LARs to limit the inspection and repair of the tubes more than 17 inches below the top of the tubesheet.

T. Hiltz This memorandum is to document the January 3, 2008, call, the licensee attendees on the call (Enclosure 1), and the questions addressed in the call (Enclosure 2). In the discussion on the three questions in Enclosure 2, the NRC staff stated the following:

1. If the tubes are not proposed to be removed from service, the licensee must provide a technical basis for the proposed plugging limit on circumferential extent of flaws located 17 inches or more from the top of the tubesheet. This limit must include allowances for flaw growth in the operating cycle and eddy current measurement error in inspecting the tubes.
2. In view of the unresolved issues pertaining to the B* distance down the tubesheet, CSGB is unable to conclude at this time that the ratio of steam line break leakage to normal operating leakage is less than 2 (the Bellwether factor) for flaws at any location within the thickness of the tubesheet. For this reason, the licensees should propose a conservative estimate of this leak rate ratio, including its technical basis, for flaws which may be located 17 inches or more below the top of the tubesheet. (Note, this ratio should be reflected in the special technical specification reporting requirement in lieu of the current value of 2.)
3. A key premise of the new interim technical position is that the welds are capable of transmitting the axial load in the tubes to the tubesheet. For this reason, the licensees should provide a discussion of their inspection and repair strategy with respect to the tube-to-tubesheet welds that will be implemented for the next SG tube inspection. (Note, the staff is interested only in whether the welds will be addressed in a consistent manner with the lower 4-inches of tubing (below 17 inches in the tubesheet) rather than the specific sampling strategy or inspection methods to be employed.)
4. Extensive documentation is not expected to be required to be submitted; however, three items are needed. These are the following: (1) justification for proposed alternate repair criteria, eddy current error, and crack growth through the operating cycle; (2) quantified rationale for bellwether ratio considered appropriate; and (3) discussion on how welds in the tubesheet are inspected and repaired. If this documentation is in previous submittals to the NRC, the licensee may reference those submittals in its application.

The NRC staff stated that axial cracks in the bottom 4 inches of the tube in the tubesheet should be acceptable. The licensees asked what time would be needed by NRC to address the LARs submitted for the spring 2008 outages. The NRC staff did not have an answer, but stated that PWR licensees should come up with a plan on how they submit these LARs and inform the staff. This ended the discussion on the three questions. It may be necessary for further discussion and future calls between the staff and the licensees.

Docket No. 50-482

Enclosures:

1. List of Attendees
2. List of Questions addressed

ML080090154 NRC-001 OFFICE NRR/LPL4/PM NRR/LPL4/LA NRR/CSGB/BC NRR/LPL4/BC NAME JDonohew JBurkhardt AHiser THiltz DATE 1/22/08 1/9/08 1/16/08 1/22/08 LIST OF ATTENDEES PARTICIPATING IN CONFERENCE CALL OF JANUARY 3, 2008 WITH WOLF CREEK NUCLEAR OPERATING CORPORATION AND OTHER PRESSURIZED WATER REACTOR (PWR) LICENSEES NAME AFFILIATION NRC: J. Donohew NRC/NRR/DORL E. Murphy NRC/NRR/DCI S. Lingam NRC/NRR/DORL A. Johnson NRC/NRR/DCI M. Thorpe-Kavanaugh NRC/NRR/DORL Licensees: S. Wideman WCNOC P. Wagner WCNOC L. Ratzlaff WCNOC G. Boyers FPL E. Korkowski FPL D. Gerber Dominion J. Smith Exelon M. Sears Exelon D. Chrzanowski Exelon S. Leshnoff Exelon R. Hall Exelon R. Gesior Exelon A. Shahkarami Exelon G. Smith Exelon W. Moore Southern Co R. Mullins Southern Co R. Kidwell Luminant B. Mays Luminant P. Fabian Salem D. Mayes Duke Energy J. Kendrickson Robinson J. Stringfellow Southern Nuclear R. Grahm Southern Nuclear P. Conley Southern Nuclear L. Hill Southern Nuclear S. LeBlanc Southern Nuclear Public: H. Lagally Westinghouse G. Whiteman Westinghouse C. Cassino Westinghouse J. Kendra Westinghouse M. Melton NEI H. Cothron EPRI Where: DCI = Division of Component Integrity DORL = Division of Operating Reactor Licensing EPRI = Electric Power Research Institute FPL = Florida Power and Light NEI = Nuclear Energy Institute NRC = Nuclear Regulatory Commission NRR = Office of Nuclear Reactor Regulation WCNOC = Wolf Creek Nuclear Operating Corporation ENCLOSURE 1

THE THREE QUESTIONS ADDRESSED IN THE CONFERENCE CALL OF JANUARY 3, 2008 The three questions/issues that E. Murphy was going to follow up on following the call on December 21, 2007, with WCNOC:

1. Is the weld excluded from inspection and can significant circumferential cracks in the weld be ignored?
2. How much of the Bellwether approach can be used to evaluate Steam Line Break leakage?
3. Level of documentation required to support interim Alternate Repair Criteria for the steam generator tubes inspected?

ENCLOSURE 2