ML13014A249

San Onofre, Unit 2, Response to Request for Additional Information (RAI 15) Regarding Confirmatory Action Letter Response (TAC No. ME9727)

ML13014A249
Person / Time
Site:	San Onofre
Issue date:	01/09/2013
From:	St.Onge R J Southern California Edison Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC ME9727, CAL-4-12-001
Download: ML13014A249 (12)

Text

SOUTHERN CALIFORNIA.EDISONAn EDISON INTERNATIONAL CompanyProprietary InformationWithhold from Public DisclosureRichard 1. St. OngeDirector. Nuclear Regulatory Affairs andEmergency PlanningJanuary 9, 201310 CFR 50.4U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001Subject:Docket No. 50-361Response to Request for Additional Information (RAI 15)Regarding Confirmatory Action Letter Response(TAC No. ME 9727)San Onofre Nuclear Generating Station, Unit 2References:1. Letter from Mr. Elmo E. Collins (USNRC) to Mr. Peter T. Dietrich (SCE), datedMarch 27, 2012, Confirmatory Action Letter 4-12-001, San Onofre NuclearGenerating Station, Units 2 and 3, Commitments to Address Steam GeneratorTube Degradation2. Letter from Mr. Peter T. Dietrich (SCE) to Mr. Elmo E. Collins (USNRC), datedOctober 3, 2012, Confirmatory Action Letter -Actions to Address SteamGenerator Tube Degradation, San Onofre Nuclear Generating Station, Unit 23. Letter from Mr. James R. Hall (USNRC) to Mr. Peter T. Dietrich (SCE), datedDecember 26, 2012, Request for Additional Information Regarding Responseto Confirmatory Action Letter, San Onofre Nuclear Generating Station, Unit 2Dear Sir or Madam,On March 27, 2012, the Nuclear Regulatory Commission (NRC) issued a Confirmatory ActionLetter (CAL) (Reference 1) to Southern California Edison (SCE) describing actions that the NRCand SCE agreed would be completed to address issues identified in the steam generator tubesof San Onofre Nuclear Generating Station (SONGS) Units 2 and 3. In a letter to the NRC datedOctober 3, 2012 (Reference 2), SCE reported completion of the Unit 2 CAL actions andincluded a Return to Service Report (RTSR) that provided details of their completion.By letter dated December 26, 2012 (Reference 3), the NRC issued Requests for AdditionalInformation (RAIs) regarding the CAL response. Enclosure 2 of this letter provides theresponse to RAI 15.Enclosure 2 of this submittal contains proprietary information. SCE requests that thisproprietary enclosure be withheld from public disclosure in accordance with 10 CFR 2.390(a)(4).Enclosure 1 provides a notarized affidavit from Mitsubishi Heavy Industries (MHI), which setsforth the basis on which the information in Enclosure 2 may be withheld from public disclosureProprietary InformationWithhold from Public DisclosureDecontrolled Upon Removal From Enclosure 2P.O. Box 128San Clemente, CA 926721,7 .07 Proprietary InformationWithhold from Public DisclosureDocument Control Desk-2-January 9, 2013by the NRC and addresses with specificity the considerations listed by paragraph (b)(4) of10 CFR 2.390. Proprietary information identified in Enclosure 2 was extracted from the sourcedocument MHI Report L5-04GA561, Retainer Bar Tube Wear Report, which is addressed in theaffidavit. Enclosure 3 provides the non-proprietary version of Enclosure 2.There are no new regulatory commitments contained in this letter. If you have any questions orrequire additional information, please call me at (949) 368-6240.Sincerely,Enclosures:1. Notarized Affidavit2. Response to RAI 15 (Proprietary)3. Response to RAI 15 (Non-proprietary)cc: E. E. Collins, Regional Administrator, NRC Region IVR. Hall, NRC Project Manager, San Onofre Units 2 and 3G. G. Warnick, NRC Senior Resident Inspector, San Onofre Units 2 and 3R. E. Lantz, Branch Chief, Division of Reactor Projects, NRC Region IVProprietary InformationWithhold from Public DisclosureDecontrolled Upon Removal From Enclosure 2 ENCLOSURE 1Notarized Affidavit MITSUBISHI HEAVY INDUSTRIES, LTD.AFFIDAVITI, Jinichi Miyaguchi, state as follows:1. I am Director, Nuclear Plant Component Designing Department, of Mitsubishi HeavyIndustries, Ltd. ("MHI"), and have been delegated the function of reviewing thereferenced MHI technical documentation to determine whether it contains informationthat should be withheld from public disclosure pursuant to 10 C.F.R. § 2.390 (a)(4) astrade secrets and commercial or financial information that is privileged or confidential.2. In accordance with my responsibilities, I have determined that the following MHIdocuments and drawings contain MHI proprietary information that should be withheldfrom public disclosure pursuant to 10 C.F.R. § 2.390 (a)(4). The drawings in their entiretyare proprietary and those pages of the documents containing proprietary informationhave been bracketed with an open and closed bracket as shown here "[ ]" / and shouldbe withheld from public disclosure.MHI documents and drawingsDocument: L5-04GA561, L5-04GA564, L5-04GA571, L5-04GA585, L5-04GA591Drawings: L5-04FU101 thru 1083. The information identified as proprietary in the enclosed document has in the past been,and will continue to be, held in confidence by MHI and its disclosure outside thecompany is limited to regulatory bodies, customers and potential customers, and theiragents, suppliers, and licensees, and others with a legitimate need for the information,and is always subject to suitable measures to protect it from unauthorized use ordisclosure.4. The basis for holding the referenced information confidential is that it describes uniquedesign, manufacturing, experimental and investigative information developed by MHIand not used in the exact form by any of MHI's competitors. This information wasdeveloped at significant cost to MHI, since it is the result of an intensive MHI effort.5. The referenced information was furnished to the Nuclear Regulatory Commission("NRC") in confidence and solely for the purpose of information to the NRC staff.

6. The referenced information is not available in public sources and could not be gatheredreadily from other publicly available information. Other than through the provisions inparagraph 3 above, MHI knows of no way the information could be lawfully acquired byorganizations or individuals outside of MHI.7. Public disclosure of the referenced information would assist competitors of MHI in theirdesign and manufacture of nuclear plant components without incurring the costs or risksassociated with the design and the manufacture of the subject component. Therefore,disclosure of the information contained in the referenced document would have thefollowing negative impacts on the competitive position of MHI in the U.S. and worldnuclear markets:A. Loss of competitive advantage due to the costs associated with development oftechnologies relating to the component design, manufacture and examination.Providing public access to such information permits competitors to duplicate ormimic the methodology without incurring the associated costs.B. Loss of competitive advantage of MHI's ability to supply replacement or newheavy components such as steam generators.

I declare under penalty of perjury that the foregoing affidavit and the matters stated thereinare true and correct to the best of my knowledge, information and belief.Executed on this 2 day of ('I U .2012.Jinichi Miyaguchi, UDirector- Nuclear Plant Component Designing DepartmentMitsubishi Heavy Industries, LTD22 0AUG. -2, 2012J nK , -.) , i a p a rD. i"Sworn to and subscribedBefore me this .dayof A 3U ic 2012Notary PublicMy Commission Expires

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Registered Number 2 2 0Date 2.2 12NOTARIAL CERTIFICATEThis is to certify that JINICHI MIYAGUCHI , Director-Nuclear PlantComponent Designing Department MITSUBISHI HEAVY INDUSTRIES, LTDhas affixed his signature in my very presence to the attacheddocument.MASAHIKO KUBOTANotary44 Akashimachi,.Chuo-Ku,Kobe, JapanKobe District Legal Affairs Bureau ENCLOSURE 3SOUTHERN CALIFORNIA EDISONRESPONSE TO REQUEST FOR ADDITIONAL INFORMATIONREGARDING RESPONSE TO CONFIRMATORY ACTION LETTERDOCKET NO. 50-361TAC NO. ME 9727Response to RAI 15(NON-PROPRIETARY)Page 1 RAI 15In Reference 1, Section 8.3.2, page 48 -How will the continued integrity of the non-stabilized,preventively-plugged tubes adjacent to the retainer bars be ensured? "Integrity" in this contextrefers to the tubes remaining intact and unable to cause damage to adjacent tubes.RESPONSEThe integrity of the non-stabilized, preventively-plugged tubes is ensured by limiting the wearresulting from retainer bar vibration. The limited vibration amplitude of the tubes and retainerbars, combined with stabilizer deployment, prevents developing a displacement/wear geometrythat could sever any of the tubes adjacent to retainer bars, either in the short term or long term.Wear mechanism of tubes adjacent to retainer barsThere are 94 tubes in each steam generator adjacent to retainer bars. Each of these tubes has7 hot leg tube support plate (TSP) support locations, 12 anti-vibration bar (AVB) supportlocations, and 7 cold leg TSP support locations. All 188 of these tubes in the Unit 2 steamgenerators (94 tubes per steam generator) were examined. No evidence of wear was found onany of these tubes at AVB and TSP intersections. Retainer bar wear was found on a total of 6tubes with 7 wear locations (one tube in SG 2E-089, Row 120 Column 132, had retainer barwear at two retainer bar locations, remaining 5 tubes had retainer bar wear at one location).The maximum wear depth of 90% tube wall thickness was found on SG 2E-089, Row 119Column 133, in a location adjacent to a retainer bar.The cause of tube wear at retainer bar locations has been evaluated by MHI. Wear marks atthe AVB intersections would be evidence of out-of-plane displacement of the U-bend. Wearmarks on the TSP intersections, especially the top TSP, would be evidence of in-planedisplacement of the U-bend. The absence of wear at the AVBs and TSPs of all 188 tubesadjacent to the retainer bar is evidence that the tubes adjacent to the retainer bar are notvibrating. MHI concluded that the tube wear adjacent to retainer bars is caused by retainer barvibration rather than tube vibration.During steam generator operation, retainer bars are subject to flow induced vibration. MHI'sanalysis of the dynamic response of retainer bars to operating conditions found that thevibration amplitude is limited and much smaller than the tube diameter of 0.75". Consequently,these retainer bar motions may damage the wall of an adjacent tube but cannot sever thesetubes. The retainer bar natural frequencies and vibration amplitudes for the first five modes areshown in Table 1 and the lowest three mode shapes are shown in Figure 1. The first modemoves in a direction parallel to the tubes. The second and third retainer bar modes areperpendicular to adjacent tubes. The maximum amplitude of the first mode due to steamgenerator operating conditions is between [ ]. Maximum amplitude of the secondmode during steam generator operating conditions is between [ ]. All highermodes have negligible vibration amplitudes.Page 2 Table 1 -Retainer Bar Natural Frequencies and Vibration AmplitudesMode 1Mode 2Mode 3Mode 4Mode 5Frequency, Hz --1AmplitudeFigure 1 -Retainer Bar Vibration Mode ShapesPage 3 Integrity of tubes adjacent to retainer barsThe six tubes with retainer bar wear indications in Unit 2 steam generators have been plugged,regardless of wear depth. To ensure that these tubes remain intact, Y2" diameter braidedstainless steel cable stabilizers have been installed in these six tubes.As a preventive measure to ensure that no in-service tubes are subject to retainer bar wear, alltubes adjacent to retainer bars have been plugged.Additionally, stabilizers have been deployed in six tubes at each retainer bar. Figure 2 shows atypical deployment. Three tubes on each side of the retainer bar have been stabilized: one tubenear the center of the retainer bar and two tubes near both ends of the retainer bar. Thestabilizers will arrest tube wear at the wear surface of the stabilizers. Since the tubes adjacentto retainer bars have no evidence of significant vibration and the retainer bar vibration amplitudeis limited, the stabilizer deployment pattern prevents any possible retainer bar or tubedisplacement/wear geometry that could sever any of the tubes adjacent to the retainer bars.o In-service tubesStabilized, preventively-plugged tubes* Non-stabilized, preventively-plugged tubesNote:Additionally, all tubes with retainerbar wear were stabilized.Figure 2 -Typical Stabilizer Deployment to Arrest Retainer Bar WearThe integrity of the non-stabilized, preventively-plugged tubes is ensured by the limited vibrationamplitude of the tubes and retainer bars, along with the number and arrangement of stabilized,preventively-plugged tubes at each retainer bar.Future inspections of retainer barsThe steam generator retainer bar wear issue has been entered into the SONGS CorrectiveAction Program (CAP). An effectiveness review requires visual inspection of the smallerdiameter retainer bars and welds during the upcoming Unit 2 mid-cycle outage. In addition, allin-service tubes will be inspected by eddy current testing in the upcoming Unit 2 mid-cycleoutage. This inspection will confirm that the non-stabilized, preventively-plugged tubes adjacentto the retainer bars are not damaging adjacent in-service tubes.Page 4