ML14027A326

Response to Request for Additional Information Concerning Relief Request No. RR-III-10

ML14027A326
Person / Time
Site:	Summer
Issue date:	01/22/2014
From:	Gatlin T South Carolina Electric & Gas Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MF1848
Download: ML14027A326 (8)

Text

Thomas D. Gatlin Vice President,Nuclear Operations 803.345.4342 A SCANA COMPANY U.S. Nuclear Regulatory Commission January 22, 2014 Document Control Desk Washington, DC 20555-0001

Subject:

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS), UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION CONCERNING RELIEF REQUEST NO. RR-II-10 (TAC NO. MF1848)

Reference:

1. Thomas D. Gatlin, SCE&G Letter to Document Control Desk, Request Relief from ASME Code Requirements in VCSNS 3r Ten Year Inservice Inspection Interval, dated May 6, 2013 [ML13129A178]

2. Thomas D. Gatlin, SCE&G Letter to Document Control Desk, Response to Request for Additional Information Concerning Relief Request No. RR-III- 10 (TAC No. MF1848), dated October 11, 2013 [ML13289A183]

3. Shawn Williams, NRC Letter to Thomas D. Gatlin, SCE&G, Request for Additional Information ConcerningRelief Request No. RR-111-1O (TAC No.

MF1848), dated December 11, 2013 [ML13340A377]

South Carolina Electric & Gas Company (SCE&G) received an NRC letter dated December 11, 2013 (Reference 3), requesting additional information (RAI) regarding thee Virgil C. Summer Nuclear Station Unit 1 relief request from ASME code requirements in the VCSNS 3 rd Ten Year Inservice Inspection Interval (Reference 1) and supplement dated October 11, 2013 (Reference 2). SCE&G has reviewed the request for additional information and hereby submits the attached response.

If you have any questions or require additional information, please contact Mr. Bruce Thompson at (803) 931-5042.

Very truly yours, TS/TDG/wm Thomas D. Gatlin Enclosure - Response to Follow-up RAI Concerning Relief Request No. RR-III-10 (TAC No. MF1848) [ML13340A377]

Attachment c: K. B. Marsh S. A. Williams S. A. Byrne NRC Resident Inspector J. B. Archie K. M. Sutton N. S. Carns NSRC J. H. Hamilton RTS (CR-12-05348)

J. W. Williams File (810.19-2)

W. M. Cherry V. M. McCree PRSF (RC-14-0006) AO~

Virgil C.Summer Station , Post Office Box 88

• Jenkinsville, SC. 29065 . F (803) 941-9776

Document Control Desk Enclosure CR-12-05348 RC-14-0006 Page 1 of 3 VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 ENCLOSURE VIRGIL C. SUMMER NUCLEAR STATION, UNIT NO. I - RESPONSE TO FOLLOW-UP REQUEST FOR ADDITIONAL INFORMATION CONCERNING RELIEF REQUEST NO. RR-III-10 (TAC NO. MF1848) [ML13340A377]

Document Control Desk Enclosure CR-12-05348 RC-14-0006 Page 2 of 3 REQUEST FOR ADDITIONAL INFORMATION REGARDING VIRGIL C. SUMMER NUCLEAR STATION UNIT 1.

SOUTH CAROLINA ELECTRIC & GAS CO.

RELIEF REQUEST NO. RR-111-10 DOCKET NO. 50-395 (TAC NO. MF1848)

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided by South Carolina Electric & Gas Co. (SCE&G, the licensee) for Virgil C. Summer Nuclear Station, Unit 1 (VCSNS) Relief Request No. RR-111-10 in its letter dated May 6, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13129A178), as supplement dated October 11, 2013 (ADAMS Accession No. ML13289A183) and has determined that additional information is necessary to complete the review of Relief Request No. RR-III-10.

Regulatory Basis:

10 CFR 50.55a(g) requires the use of ASME Code, Section Xl for in-service inspection (ISI) examinations. The relevant requirements of the ASME Code,Section XI for the pressurizer surge nozzle examination are that essentially 100% of the nozzle-to-vessel shell weld be examined. Code Case N-460, which is approved for use by the NRC in Regulatory Guide 1.147, Revision 16, "Inservice Inspection Code Case Acceptability, ASME Section Xl, Division 1,"

clarifies "essentially 100 percent" to be greater than 90 percent coverage of the examination volume, or surface area, as applicable. Since the licensee's examination of the pressurizer surge nozzle-to-vessel shell weld only obtained 51% coverage, the NRC needs to understand clearly how that coverage was achieved in order to satisfy the requirements of 10 CFR 50.55a(a)(3), which states, in part, that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if the applicant demonstrates that: (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii)compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Follow-up RAI 6.c response on October 11, 2013 The licensee's response to RAI6(c) did not provide the specifics necessary for the NRC to fully understand how the value of 51% coverage was determined. Describe how the value of 51% was determined. Provide the calculation and an illustration as necessary for clarity. From the information previously provided, it appears that the coverage from 450 and 600 probes should be different, and coverage may also be different from each scan direction, especially in light of the fact that the vendor appears to be taking credit for capturing additional coverage from performing the examination in the gaps between the heater penetrations on the head side. Specifically, describe how coverage from each

Document Control Desk Enclosure CR-12-05348 RC-14-0006 Page 3 of 3 of the transducers and scan directions were credited in determining the 51% coverage value. Address whether credit may be given for one angle only, or if coverage with both angles is required for credit.

SCE&G Response VCSNS vendor WesDyne International, who performed the ultrasonic examination of nozzle to shell weld # 1-2100A-8 during Refueling Outage 20, has provided additional information regarding the ultrasonic examination of the weld in question. The examination of the pressurizer surge nozzle to the shell weld was limited due to one sided access (nozzle side) and heater tube penetrations (shell side) that prevented unobstructed scanning. No credit for coverage was taken for either angle below the 60 degree metal path plot, and no credit was taken for areas that achieved coverage with just one angle.

The top portion of the weld was the only area where both angles (45 degrees and 60 degrees) achieved complete coverage; therefore, that was the number that was reflected in the previous weld material coverage calculation (i.e., 51 percent in References 1 and 2 listed in the cover letter). With a holistic analysis of the ultrasonic examination for nozzle to shell weld # 1-2100A-8, new results are being provided for the top portion of the weld where both angles achieved complete coverage (provided in attachment). The percentage for the shell side is now 46 percent, instead of 51 percent, while the percentage for the nozzle side is now 58 percent, instead of 51 percent. The combined coverage from both directions for the axial scanning was conservatively recorded as 51 percent originally, and is shown to be 52 percent in the attached calculations. Calculations provided by the vendor were based on total area of the weld scanned versus total area of weld covered with both angles per direction. The enclosed attachment provides full detail of WesDyne International's analysis.

In addition, WesDyne International explained why oscillating the transducers to make an attempt to scan around the penetrations on the shell side to provide a small increase in total coverage was not considered. Assumptions needed for that option would not be easily defendable. This is also discussed in the enclosed attachment.

Document Control Desk Attachment CR-12-05348 RC-14-0006 Page 1 of 4 VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT I DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 ATTACHMENT WESDYNE LETTER TO VCSNS, DATED DECEMBER 6, 2013, REGARDING ULTRASONIC EXAMINATION OF NOZZLE TO SHELL WELD # 1-2100A-8 DURING REFUELING OUTAGE RF20

~WESDynlE A Westinghouse Electric Company December 6, 2013 V.C. Summer Nuclear Power Station

Subject:

Ultrasonic examination of nozzle to shell weld # 1-2100A-8 during RF20 Examination of the pressurizer surge nozzle to shell weld # 1-2100-8 was limited due to one sided access (nozzle side) and heater tube penetrations (shell side) preventing unobstructed scanning.

Scanning to the maximum extent practical was performed in four directions i.e. both directions perpendicular to the weld and both directions parallel to the weld utilizing 450 and 600 shear wave angles. Scanning for indications lying perpendicular to the weld was accomplished by scanning tangential to the weld and oscillating the transducer +/- 15'-20o.

A ring of heater penetrations prevented complete access from the shell side of the weld.

This ring consisted of 20 (-1.5" diameter) penetrations separated by approximately 3.0 inches with one 18.5 inch gap at one quadrant (vessel O°). The gap between the tubes was not enough to pass the search units (1/2" x 1.0") through and still maintain grip and control.

The obstructions (nozzle on one side of the weld and penetrations on the other) prevented the search units from getting back away from the weld far enough to reach the bottom portion of the weld. (see attached sketch Figure 1)

Basically no credit was taken for either angle below the 600 metal path plot in areas on the shell side, in front of the penetrations and on the nozzle side where the transducers were unable to scan back due to the nozzle blended radius. Areas that got coverage with just one angle were conservatively not credited for coverage. Single angle coverage credit was not considered. The top portion of the weld is the only area where both angles get complete coverage and therefore it is that number that is reflected in the calculation.

Calculations are based on total area of weld versus total area of weld covered with both angles in both directions. WesDyne considers the CW and CCW coverage to be complete and therefore 100%. Perpendicular weld coverage with both angles combined was conservatively estimated to be 52%. Calculated as 4 independent scans, the totals are:

Noz Side = 58% Shell Side = 46% CW = 100% CCW = 100%

304 /4 = 76%

"Apowerful part ofyour team"

Fq1WESDynE AWastinghouse Electnc Company Weld coverage based on % of weld material scanned from both dkedions wih both tansducers Mpepdmular and parWal to fe weld (4 d,&ecboks)

Assumes no scannV between penetrations Wed ldl (CtO) - 2.0" Wsjdcvt-yr Wed Ana I Vbkame - 4.0 sq in1314in'

£ -ýD eo Noz Side 58% coverage Shd Side 46% coverage CW Scan = 100%% corage CCW Scan 1NS.coerag Aw TnAi40e -. Wx-?6'12-.W4uoIn TOTAL COVERAGE Thu~e It- 2r *A712 -,100sq hi 30414 -76%

Tft)3s. sq in WGOdDea TrmngeE- 2ra1.0rIZ-.14Ssqki rsedF- r t 2r *OS6qin Tr~ov G.- W x.T12 -.O97aq in lrtk t,1 $a in Noz We. owna - 2S%or SO% ft w efts Stag Side coverage - 23% or 46% ftor "li W& 9Wded -bloat thud 6 dsg uiV Ww is te aem altege tmwe come"g Wa lid aa**W NOT TO SCALE Figure 1 "A powerfulpart of your team"

AWostmnghouseElect&iCompany There is an argument that if we oscillate the transducers and attempt to scan around the penetrations on the shell side, we could get more coverage. This is probably true but several assumptions would have to be made. Because of the difference in circumference between the penetration row diameter and the smaller weld circumference diameter, it could be possible to assume coverage of the weld area without the typical transducer overlap at the penetration ring. Additionally, transducer oscillation +/- 200 and beam spread (not normally credited) could conceivably provide additional coverage between the penetrations. If these considerations are viable then the coverage on the shell side of the weld could increase to approximately 83%. (see Figure 2)

Weld coverage based an %of weld manwial scanned Wonbolth dukecions with both ransducers perpenducidr and Parae So the weld (4 drecions)

Asmes addina coverage by scatewi between Pene~aions Noz Sids 6=%coverage Shlle Sid 74.8% coverage CW Scan = 100%% coverage CCW scan = j00covenage TOTAL. COVERAGE 332.14 - 832%

Adtion ShelSde Qsa C alveatio "9spames 1.S"ea =285S 3A Gap in heater ring @0 deg - ILE mer Weld Ckvcunernce =Tr 47177=61% of100% coverage Ph tus ,e ntanetg 30"had 46%coverage 13.8%

13.8%+61%- 7428%

Weld width (00)= 2.06 Wel wdth (ID)- .e" Weld Cuc - 77" N Side a WeldrAa IVokorm Red D- 76'x 108 = 810sqin 4,08qm1314in3 TrangleE- 27xl.OI2= 145*qin 125-TVP RecdF a -3"x 2r .066 sq in TriangleG- .AS"x.3"I2 =.097sqin C.AR. Totals 1.19sqin 32S TV.p 1.1912.04 = 56%

Tranducer Figure 2 Michael McKaig WesDyne NDE Level III "A powerful part of your team "