Nuclear Operating Company

South Tes Pro/ect Electric Generating Station PO Box 289 Wadsworth, Tesas 77483

February 7, 2011NOC-AE-1 1002633File No.: G2510 CFR 50.55a

U. S. Nuclear Regulatory CommissionAttention: Document Control DeskOne White Flint North11555 Rockville PikeRockville, MD 20852-2746

South Texas ProjectUnits 1 and 2

Docket Nos. STN 50-498, STN 50-499Amended Request for Relief from ASME Section XI Code Requirements for

Reactor Pressure Vessel Flange Insert Non-Destructive Examination(TAC No. ME4764/ME4765) (Relief Request RR-ENG-3-02)

Reference: Marco Ruvalcaba, STP Nuclear Operating Company, to NRC Document ControlDesk, "Request for Relief from ASME Section XI Code Requirements for ReactorPressure Vessel Flange Insert Non-Destructive Examination (Relief Request RR-ENG-3-02)," dated September 20, 2010 (NOC-AE-1 0002593) (ML1 02700173)

In accordance with the provisions of 10 CFR 50.55a(a)(3)(i), the STP Nuclear OperatingCompany (STPNOC) requested relief from the ASME Section XI code nondestructiveexamination requirements applicable to the South Texas Project reactor pressure vessel flangeinserts (referenced above). As an alternative to the visual examination, the South Texas Projectproposes to perform a straight beam ultrasonic examination from the top surface of each insert(36 per unit) as described in the attached relief request. This amended request incorporatesadditional information in response to NRC reviewer comments. Revised and new text isindicated in the margin.

There are no commitments in this correspondence.

STPNOC requests NRC review and approval of this relief request by April 1, 2011, to supportimplementation of the Unit 1 and Unit 2 Ten Year Inservice Inspection Plan for the thirdinspection interval. The requested date is flexible.

If there are any questions, please contact either Mr. Philip Walker at 361-972-8392 or me at361-972-7904.

M arco RuvalcabaManager,Test and Programs Engineering

PLWAttachment: Amended Request for Relief from ASME Section Xl Code Requirements for

Reactor Pressure Vessel Flange Insert Non-Destructive Examination (ReliefRequest RR-ENG-3-02)

STI: 32816652

NOC-AE-1 1002633Page 2 of 2

cc: (paper copy) (electronic copy)

Regional Administrator, Region IVU. S. Nuclear Regulatory Commission612 East Lamar Blvd., Suite 4004Arlington, TX 76011-4125

Mohan C. ThadaniSenior Project ManagerU.S. Nuclear Regulatory CommissionOne White Flint North (MS 8 G14)11555 Rockville PikeRockville, MD 20852

Senior Resident InspectorU. S. Nuclear Regulatory CommissionP. 0. Box 289, Mail Code: MN1 16Wadsworth, TX 77483

C. M. CanadyCity of AustinElectric Utility Department721 Barton Springs RoadAustin, TX 78704

A. H. Gutterman, Esq.Morgan, Lewis & Bockius LLP

Mohan C. ThadaniU. S. Nuclear Regulatory Commission

Peter NemethCrain Caton & James, P.C.

C. MeleCity of Austin

E. AlarconK. PolioRichard PenaCity Public Service

John RaganC. Callaway, Esq.J. von SuskilNRG South Texas LP

Richard A. RatliffAlice RogersTexas Department of State Health Services

AttachmentNOC-AE-1 1002633Page 1 of 9

SOUTH TEXAS PROJECTUNITS 1 AND 2

AMENDED REQUEST FOR RELIEF FROM ASME SECTION Xl CODE REQUIREMENTS FORREACTOR PRESSURE VESSEL FLANGE INSERT NON-DESTRUCTIVE EXAMINATION

(RELIEF REQUEST RR-ENG-3-02)

A. Components Affected

(a) Component: Reactor Pressure Vessel

(b) Description: Roto-Lok flange inserts (bushings)

The vessel insert material specification is SA-540, Class 3, Gr. B-24 (as modified byCode Case 1605). There are 36 flange inserts per unit. Figure 1 is a cut-away showingthe dimensions of a typical flange bushing mounted in the reactor pressure vesselflange. Figures 2A and 2B show the flange bushing ultrasonic examination volume.

(c) Class: ASME Code Class 1

B. Applicable Code Requirement

The applicable code is ASME Section Xl, 2004 Edition (no addenda).

IWB-2500, Table IWB-2500-1, Code Category B-G-1, Item Number B6.50 requires that allbushings receive a visual, VT-1 examination each inspection interval. Examination ofbushings and threads in flange base material is required only when the connections aredisassembled. Bushings may be inspected in place.

C. Basis for Relief from Code Requirements

In accordance with the provisions of 10 CFR 50.55a(a)(3)(i), STP Nuclear OperatingCompany (STPNOC) requests relief from the Section Xl code requirement for a visual, VT-1examination of reactor pressure vessel bushings and threads in flange base material. Roto-Lok flange inserts (see attached illustration) consist of conventional threads on the outsidesurface and three rows of lugs on the inside surface. With the Roto-Lok flange inserts inplace in the reactor vessel flange, portions of the lugs are not accessible for Visual, VT-1examination.

D. Alternative Examination:

Pursuant to 10 CFR 50.55a(a)(3)(i), STPNOC proposes to perform a straight beamultrasonic examination of the vessel inserts from the top end of the vessel inserts as analternative to the Code-required Visual, VT-1 examination. The proposed alternativeexamination is to be performed concurrently with that of the vessel flange thread volumetricexamination to inspect for radial-circumferential flaws.

E. Justification for Granting Relief

Performing the examination concurrent with the vessel flange thread ultrasonic examinationwill reduce total radiation exposure. The ultrasonic technique will examine the entire length

AttachmentNOC-AE-i 1002633Page 2 of 9

of the vessel insert and is superior to the VT-1 examination. The straight beam ultrasonicexamination procedure has been demonstrated to ensure examination adequacy.

Volumetric examination in lieu of the Visual, VT-1 examination was successfully performedduring the second inservice inspection interval at STP Units 1 (September 25, 2000 toSeptember 24, 2010) and 2 (October 19, 2000 to October 18, 2010). Figures 2A and 2Bdepict the volume achieved by ultrasonic examination.

The initial demonstration was performed December 7, 1998, in accordance with ultrasonictechnical instructions. Ultrasonic technical instructions are demonstrated at the ElectricPower Research Institute (EPRI) in accordance with the requirements of ASME Section Xl,Appendix VIII, 1995 Edition with Addenda through 1996, as modified by the PerformanceDemonstration Initiative (PDI) Program Description.

A calibration block was prepared in accordance with Table VI-2430-1 of ASME Section Xl,Appendix VI, to examine the entire length of the vessel insert. The calibration block wasfabricated from an actual spare reactor pressure vessel insert. The calibration blockincludes notches at different depths on both the inside and outside surfaces to ensureexamination volume coverage and sensitivity were obtained. The notches arerepresentative of flaws that would be found in-service. The demonstration confirmed that allinside and outside surface indications can be easily observed at scanning speed.

The manual, contact, pulse echo, ultrasonic method utilizes a 1-inch round 0-degreelongitudinal wave transducer. The inserts are examined from the top with the beam passingthrough the length of the insert.

Pictures of the calibration standard are attached:

Figure 3: This displays the inner surface of the calibration block for examining a reactorbushing insert. Machined notches at 8, 14, 20, and 23 inches from the topsurface of the bushing are used to demonstrate the ability to discern crack-like indications at the inner bore surface.

Figure 4: This displays the outer surface of the calibration block for examining a reactorbushing insert. Machined notches at 4, 10, and 16 inches from the topsurface are used to demonstrate the ability to detect indications located in thegrooved area between threads (thread root).

The proposed alternate straight beam ultrasonic examine will ensure continued structuralintegrity of the vessel inserts and provide a comparable or superior level of quality andsafety when compared to the Code-required Visual, VT-1 examination.

F. Implementation Schedule

STPNOC requests relief from ASME Section Xl nondestructive examination requirements forthe reactor pressure vessel flange inserts for the duration of the third ten-year inserviceinspection interval of Units 1 and 2. The third interval began September 25, 2010 (Unit 1)and October 19, 2010 (Unit 2) and ends September 24, 2020 and October 18, 2020,respectively. The Nuclear Regulatory Commission is requested to review and approve this

AttachmentNOC-AE-1 1002633Page 3 of 9

relief request by April 1, 2011, to support implementation of the Unit 1 and Unit 2 Ten Year

Inservice Inspection Plan for the third interval. The requested date is flexible.

G. Precedent

Relief from this examination requirement to apply the proposed alternative at the SouthTexas Project was previously approved by the NRC for the second 10-year inserviceinspection interval for STP Units 1 (September 25, 2000 to September 24, 2010) and 2(October 19, 2000 to October 18, 2010):

Inservice Inspection Program, Relief Request RR-ENG-2-5 (June 17, 1999) (TACNos. MA5462 and MA5463)

AttachmentNOC-AE-1 1002633Page 4 of 9

SOUTH TEXAS PROJECTRELIEF REQUEST RR-ENG-3-02

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION

The Nuclear Regulatory Commission (NRC) staff reviewed the information provided by STPNuclear Operating Company for South Texas Project Units 1 and 2, in its letter datedSeptember 20, 2010, and determined that additional information is necessary to complete thereview of Relief Request RR-ENG-3-02.

1 . Please provide the start and end dates of the third 10-year inservice inspection intervalfor STP Units 1 and 2.

Response:

This information is incorporated into Section F of amended RR-ENG-3-02.

2. Section E of RR-ENG-3-02 states that the "straight beam ultrasonic examinationprocedure has been demonstrated to ensure examination adequacy." Please provide adetailed description of this demonstration, including mockups/samples used, method(s)demonstrated, and results.

Response:

This information is incorporated into Section E of amended RR-ENG-3-02.

3. What flaws are expected in these components? Unless addressed in response toquestion 2 above, please address whether the mockups used in the demonstration ofthe UT technique contained flaws representative of those found inservice.

Response

As addressed in response to question 2, the mockups used in demonstration of the UTtechnique include flaws representative of those found in service. See Figures 3 and 4.

4. The illustration of the Roto-lok flange insert provided in RR-ENG-3-02 is not sufficient forunderstanding the Code-required examination surface as well as what is going to beexamined with UT in lieu of VT. Please provide additional illustrations to clarify the Coderequired VT and proposed UT examination.

Response

Figure 1 shows the dimensions of a flange bushing insert.

Figures 2A and 2B show the flange bushing volume to be examined ultrasonically.

5. How many Roto-Lok flange inserts are on each reactor vessel?

Response

There are 36 Roto-Lok flange inserts on each reactor vessel.

AttachmentNOC-AE-1 1002633Page 5 of 9

FLANGE BUSHING THREADS

16.75"

REACTORPRESSUREVESSELFLANGE

23.875"

9.913"

12.750"

FIGURE 1FLANGE BUSHING DIMENSIONS

EXAMINATION VOLUME(INSIDE SURFACE)

AttachmentNOC-AE-1 1002633Page 6 of 9

N

EXAMINATION VOLUME(OUTSIDE THREADS)

AF

F R

EXAMINATION VOLUME(OUTSIDE THREADS)

zz

FIId[.d[.dLl&d- m

FIGURE 2AFLANGE BUSHING ULTRASONIC EXAMINATION VOLUME

AttachmentNOC-AE-1 1002633Page 7 of 9

EXAMINATION VOLUME(OUTSIDE THREADS)

EXAMINATION VOLUME(INSIDE SURFACE)

FIGURE 2BFLANGE BUSHING ULTRASONIC EXAMINATION VOLUME (TOP VIEW)

AttachmentNOC-AE-1 1002633Page 8 of 9

I

FIGURE 3

REACTOR PRESSURE VESSEL FLANGE BUSHINGCALIBRATION BLOCK (INTERIOR SURFACE)

AttachmentNOC-AE-1 1002633Page 9 of 9

16-inhch