ML060830024

Request for Additional Information on the Proposed C* Amendment for Steam Generator Tube Inspection and Repair in the Tubesheet

ML060830024
Person / Time
Site:	San Onofre
Issue date:	03/23/2006
From:	Kalyanam N Plant Licensing Branch III-2
To:	Rosenblum R Southern California Edison Co
Kalyanam N, NRR/DLPM, 415-1480
References
TAC MC8850, TAC MC8851
Download: ML060830024 (7)

Text

March 23, 2006 Mr. Richard M. Rosenblum Senior Vice President and Chief Nuclear Officer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128

SUBJECT:

SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 -

REQUEST FOR ADDITIONAL INFORMATION ON THE PROPOSED C*

AMENDMENT FOR STEAM GENERATOR TUBE INSPECTION AND REPAIR IN THE TUBESHEET (TAC NOS. MC8850 and MC8851)

Dear Mr. Rosenblum:

By letter dated November 3, 2005 (Agencywide Documents Access and Management System Accession No. ML053110284), Southern California Edison submitted an application to change the San Onofre Nuclear Generating Station, Units 2 and 3, technical specifications related to steam generator tube inspection. The changes would define the depth of the required tube inspections and plugging criteria within the tubesheet.

After reviewing your request, the Nuclear Regulatory Commission staff has determined that additional information is required to complete the review. We discussed this information with your staff by telephone and they agreed to provide the additional information requested in the enclosure by April 30, 2006.

If you have any questions, please contact me at (301) 415-1480.

Sincerely,

/RA/

N. Kalyanam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362

Enclosure:

Request for Additional Information cc w/encl: See next page

March 23, 2006 Mr. Richard M. Rosenblum Senior Vice President and Chief Nuclear Officer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128

SUBJECT:

SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 -

REQUEST FOR ADDITIONAL INFORMATION ON THE PROPOSED C*

AMENDMENT FOR STEAM GENERATOR TUBE INSPECTION AND REPAIR IN THE TUBESHEET (TAC NOS. MC8850 and MC8851)

Dear Mr. Rosenblum:

By letter dated November 3, 2005 (Agencywide Documents Access and Management System Accession No. ML053110284), Southern California Edison submitted an application to change the San Onofre Nuclear Generating Station, Units 2 and 3, technical specifications related to steam generator tube inspection. The changes would define the depth of the required tube inspections and plugging criteria within the tubesheet.

After reviewing your request, the Nuclear Regulatory Commission staff has determined that additional information is required to complete the review. We discussed this information with your staff by telephone and they agreed to provide the additional information requested in the enclosure by April 30, 2006.

If you have any questions, please contact me at (301) 415-1480.

Sincerely,

/RA/

N. Kalyanam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362

Enclosure:

Request for Additional Information cc w/encl: See next page DISTRIBUTION PUBLIC LPLIV r/f RidsNrrDorl (CHaney/CHolden)

RidsNrrDorlLplg (DTerao) RidsNrrPMNKalyanam RidsNrrLALFeizollahi RidsNrrDciCsgb RidsAcrsAcnwMailCenter RidsOgcRp RidsRgn4MailCenter (TPruett) RidsNrrDorlDpr GMakar ACCESSION NO: ML060830024

• No major change from Staff provided RAI OFFICE NRR/LPL4/PM NRR/LPL4/LA NRR/DE/EEEB* NRR/LPL4/BC NAME NKalyanam LFeizollahi AHiser DTerao DATE 3/22/06 3/22/06 3/26/06 3/23/06 OFFICIAL RECORD COPY DOCUMENT NAME: E:\Filenet\ML060830024.wpd

REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST FOR PROPOSED TECHNICAL SPECIFICATION CHANGE REGARDING REPAIR CRITERIA AND INSPECTION DEPTH FOR STEAM GENERATOR TUBES WITHIN THE TUBESHEET REGION SOUTHERN CALIFORNIA EDISON SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362 By letter dated November 3, 2005 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML053110284), Southern California Edison submitted an application to change the San Onofre Nuclear Generating Station (SONGS), Units 2 and 3, technical specifications (TS) related to steam generator tube inspection. The changes would define the depth of the required tube inspections and plugging criteria within the tubesheet, with the depth of inspection defined as C* (C-star). The technical basis for these changes was initially documented for the hot leg in Westinghouse topical report WCAP-16208-P, Revision 0, NDE Inspection Length for CE Steam Generator Tubesheet Region Explosive Expansions, dated October 2004.

In a letter dated December 16, 2004 (ADAMS Accession No. ML043510406), the Nuclear Regulatory Commission (NRC) staff requested additional information from Florida Power and Light (FPL) about their C* amendment application for St. Lucie, Unit 2. FPLs response to this request was issued March 31, 2005 (ADAMS Accession No. ML050960517), and Revision 1 of WCAP-16208-NP was subsequently issued in May 2005 (ADAMS Accession No. ML051520417).

The licensee for SONGS, Units 2 and 3, referenced WCAP-16208, Revision 1, and submitted a Supplement 1, which applies the C* methodology in the cold leg of the SONGS, Units 2 and 3, steam generators.

In order to complete its review of the license amendment for SONGS, Units 2 and 3, the NRC staff needs the additional information requested below.

1. Please confirm that your operating parameters (e.g., temperature, pressure, etc.) will always be conservatively bounded by the conditions for which the hot-leg and cold-leg C* distances were determined in WCAP-16208-P, Revision 1 (including Supplement 1).

If the conditions will not always be bounded, what controls are in place to ensure an adequate depth of inspection in the tubesheet?

For example, please confirm that the hot-leg temperature at SONGS, Unit 2 and 3, is greater than that assumed (600 degrees Fahrenheit) in the tubesheet deflection analyses and in determining the increase in contact pressure as a result of differential thermal expansion between the tube and the tubesheet. If the hot-leg temperature in either unit is lower than 600 degrees, please discuss the effect on the C* distance.

2. The SONGS, Units 2 and 3, currently allow the installation of leak-tight sleeves according to Asea Brown Boveri/Combustion Engineering, Inc. (ABB/CE) Topical Report CEN-630-P, Revision 2. The proposed revision of TS 5.5.2.11.h excludes from inspection the portions of the tube below the C* distance in the tubesheet. Since sleeves could extend into the tubesheet below the C* distance, the proposed TS would no longer require the sleeve or tube to be inspected in this region. Sleeves were not addressed in the testing and analysis used to justify excluding part of the tube from inspection (WCAP-16208-P, Revision 1, including Supplement 1). What plans do you have to ensure the lower ends of sleeves (i.e., those within the tubesheet below the C*

distance) will be inspected, including the pressure-retaining portion of the parent tube in contact with the sleeve, the sleeve-to-tube weld, and the pressure retaining portion of the sleeve? Please discuss your plans to modify your TS to address this issue.

Consider, for example, the following wording:

For a tube with no portion of a sleeve extending below (a) 10.4 inches from the bottom of the hot-leg expansion transition or the top of the tubesheet (whichever is lower) or (b) 10.7 inches from the bottom of the cold-leg expansion transition or the top of the tubesheet (whichever is lower), a tube inspection means an inspection of the steam generator tube from 10.4 inches below the bottom of the hot-leg expansion transition or top of the tubesheet (whichever is lower) completely around the U-bend to 10.7-inches below the bottom of the cold-leg expansion transition or top of the tubesheet (whichever is lower).

For all other tubes, a tube inspection means an inspection from the bottom of the sleeve completely around the U-bend to either (a) 10.4 inches below the bottom of the hot-leg expansion transition or top of the tubesheet (whichever is lower) or (b) 10.7 inches below the bottom of the cold-leg expansion transition or top of the tubesheet (whichever is lower), as appropriate.

3. It is the NRC staffs understanding that load at first slip, rather than maximum load, was reported and plotted in Figure 5-1 of WCAP-16208-P, Revision 1. If the load at first slip was not used in all cases, please discuss the effect on the required inspection distance if the load at first slip was used. In addition, if the load at first slip was not used in Table 6-8 of WCAP-16208-P, Revision 1 (Burst Based Inspection Length), please provide Table 6-8 values to confirm the 10.4 inch (hot leg) and 10.7 inch (cold leg) proposed inspection distances are bounded when the most limiting specimen is evaluated using load at first slip. In addition, please discuss the effect on the leakage-based inspection distance (Tables 6-9 and 6-15). If the leakage-based inspection length increased, discuss your plans to modify your TS accordingly.

4. Please discuss your plans to revise your TS to include the reporting requirements listed below:

(a) Number of total indications, location of each indication, orientation of each indication, size of each indication, and whether the indications are initiated from the inside or outside surface.

(b) The cumulative number of indications detected in the tubesheet region as a function of elevation within the tubesheet.

(c) Projected end-of-cycle (EOC) accident-induced leakage from tubesheet indications. This leakage shall be combined with the postulated EOC accident-induced leakage from all other sources. If the preliminary estimated total projected EOC accident-induced leakage from all sources exceeds the leakage limit, the NRC staff shall be notified prior to unit restart.

5. The proposed revision of TS 5.5.2.11.f.1.f provides exceptions, based on the C*

distance, to applying the tube Repair Limit within the hot-leg tubesheet for tubes that have not been repaired and tubes that have been repaired (sleeved). These exceptions are not included for the cold-leg tubesheet. It is, therefore, the NRC staffs understanding that any tube degradation detected below the bottom of the cold-leg expansion transition or cold-leg top-of-tubesheet, whichever is higher, shall be removed from service or repaired on detection. Please confirm or correct the staffs understanding. Please provide a justification for the difference in plugging/repair requirements for degradation in the hot-leg and cold-leg tubesheet in your proposed TS, or discuss your plans for modifying the proposed TS for consistency between the hot-and cold-leg tubesheet repair requirements.

6. According to Enclosure 3 to your November 3, 2005, submittal, the primary-to-secondary accident-induced leakage limit for SONGS, Units 2 and 3, is 0.5 gpm per steam generator (SG). For Unit 3, this limit is the same as the limiting condition for operation in your TS LCO 3.4.13.d since no sleeves are installed. For Unit 2, LCO 3.4.13.d specifies a maximum operational leakage rate of 0.1 gpm per SG since sleeves are installed. Since the operational leakage limit is equal to the accident-induced leakage limit, please address the following for Unit 3:

a. During a steamline break the differential pressure across the tubes is greater than the differential pressure during normal operation. As a result, the primary-to-secondary leakage may be greater during a steamline break than during normal operation. Since you could be operating with leakage as high as your normal operating leakage limit (0.5 gpm), the amount of leakage during a steamline break (or other postulated accidents) could be greater than that assumed in your accident analyses. If so, please discuss what controls are in place to ensure that you do not exceed your accident-induced leakage limit simply as a result of normal operating leakage.

b. As part of the C* amendment, you will be assuming there is 0.2 gpm accident-induced primary-to-secondary leakage as a result of flaws within the tubesheet region. In addition, you may have accident-induced leakage from other sources such as sleeves or other degradation. This latter amount of leakage will need to be limited to 0.3 gpm to ensure you do not exceed your accident-induced leakage limits in your updated final safety analysis report (UFSAR). Since the source of any normal operating leakage is not known (i.e., it could be from sources other than the tubesheet or sleeves or other defects assumed to leak in

your operational assessment) and it could be as high as your TS limit of 0.5 gpm (or even higher during some postulated accidents due to the increased differential pressure), it is not clear that you will be able to stay within your accident-induced leakage limits unless you change your TS normal operating leakage or your UFSAR accident analysis leakage limit. Please discuss whether you will be able to stay within your accident-induced leakage limits and your proposed C* inspection requirements.

7. Do all of the tubes in your SGs have adequate expansion in the tubesheet to meet the leakage and pullout criteria? That is, are all of the tubes nominally expanded for the full depth of the tubesheet? If any tubes are not nominally expanded for the full depth of the tubesheet, have you verified that the expansion length is adequate to ensure structural and leakage integrity consistent with the C* approach? For those tubes which may not have adequate expansion lengths, discuss how you will ensure structural and leakage integrity for these tubes (e.g., inspection of the tube-to-tubesheet weld). Also, discuss whether any changes are needed to your TSs to address this issue.

8. Please describe the expected condition of the tube-to-tubesheet crevice, such as the amount of corrosion product and sludge at the top of the tubesheet. Discuss the effects of these conditions on tube-to-tubesheet contact pressure and the potential for leakage.

San Onofre Nuclear Generating Station Units 2 and 3 cc:

Mr. Daniel P. Breig Resident Inspector/San Onofre NPS Southern California Edison Company c/o U.S. Nuclear Regulatory Commission San Onofre Nuclear Generating Station Post Office Box 4329 P. O. Box 128 San Clemente, CA 92674 San Clemente, CA 92674-0128 Mayor Mr. Douglas K. Porter, Esquire City of San Clemente Southern California Edison Company 100 Avenida Presidio 2244 Walnut Grove Avenue San Clemente, CA 92672 Rosemead, CA 91770 Mr. James T. Reilly Mr. David Spath, Chief Southern California Edison Company Division of Drinking Water and San Onofre Nuclear Generating Station Environmental Management P.O. Box 128 P. O. Box 942732 San Clemente, CA 92674-0128 Sacramento, CA 94234-7320 Mr. James D. Boyd, Commissioner Chairman, Board of Supervisors California Energy Commission County of San Diego 1516 Ninth Street (MS 31) 1600 Pacific Highway, Room 335 Sacramento, CA 95814 San Diego, CA 92101 Mr. Ray Waldo, Vice President Mark L. Parsons Southern California Edison Company Deputy City Attorney San Onofre Nuclear Generating Station City of Riverside P.O. Box 128 3900 Main Street San Clemente, CA 92764-0128 Riverside, CA 92522 Mr. Brian Katz Mr. Gary L. Nolff Southern California Edison Company Assistant Director - Resources San Onofre Nuclear Generating Station City of Riverside P.O. Box 128 3900 Main Street San Clemente, CA 92764-0128 Riverside, CA 92522 Mr. Steve Hsu Regional Administrator, Region IV Department of Health Services U.S. Nuclear Regulatory Commission Radiologic Health Branch 611 Ryan Plaza Drive, Suite 400 MS 7610, P.O. Box 997414 Arlington, TX 76011-8064 Sacramento, CA 95899 Mr. Michael Olson Mr. A. Edward Scherer San Diego Gas & Electric Company Southern California Edison Company P.O. Box 1831 San Onofre Nuclear Generating Station San Diego, CA 92112-4150 P.O. Box 128 San Clemente, CA 92674-0128 Mr. Ed Bailey, Chief Radiologic Health Branch State Department of Health Services Post Office Box 997414 (MS7610)

Sacramento, CA 95899-7414 February 2006