NOC-AE-12002933, Clarification to Requests for Additional Information for the South Texas Project License Renewal Application Aging Management Program, Set 13 (Supplemental) (TAC Nos. ME4936 and ME4937)

Clarification to Requests for Additional Information for the South Texas Project License Renewal Application Aging Management Program, Set 13 (Supplemental) (TAC Nos. ME4936 and ME4937)

ML12361A024
Person / Time
Site:	South Texas
Issue date:	12/11/2012
From:	Rencurrel D South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-12002933, TAC ME4936, TAC ME4937
Download: ML12361A024 (11)

Text

Nuclear Operating Company South Tewas ProjectElectric Gencratin* Station PO. Box 289 Wadsworth. Texas 77483 __A_--

December 11, 2012 NOC-AE-12002933 10 CFR 54 STI: 33629992 File: G25 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Clarification to Requests for Additional Information for the South Texas Project License Renewal Application Aging Management Program, Set 13 (Supplemental) (TAC Nos. ME4936 and ME4937)

References:

1. STPNOC letter dated October 25, 2010, from G. T. Powell to NRC Document Control Desk, "License Renewal Application" (NOC-AE-1 0002607)

(ML103010257)

2. STPNOC letter dated April 17, 2012 from D. W. Rencurrel to NRC Document Control Desk, "Response to Requests for Additional Information for the South Texas Project License Renewal Application Aging Management Program, Set 13 (Supplemental) and Set 15 (TAC Nos. ME4936 and ME4937)"

(NOC-AE-12002830) (ML12114A231)

By Reference 1, STP Nuclear Operating Company (STPNOC) submitted a License Renewal Application (LRA) for South Texas Project (STP) Units 1 and 2. By Reference 2, STPNOC provided responses to requests for additional information by the Nuclear Regulatory Commission regarding the STP application. Clarification to the response to request for additional information (RAI) Set 13 (Supplemental) RAI 4.2.2-1 that was provided in Reference 2 is described in Enclosure 1 to this letter. Changes to LRA pages described in Enclosure 1 are depicted as line-in/line-out pages in Enclosure 2.

There are no regulatory commitments in this letter.

Should you have any questions regarding this letter, please contact either Arden Aldridge, STP License Renewal Project Lead, at (361) 972-8243 or Ken Taplett, STP License Renewal Project regulatory point-of-contact, at (361) 972-8416.

NOC-AE-12002933 Page 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on /2 /*to/ _

Date Senior Vice President KJT

Enclosures:

1. STPNOC Clarification to Response to Request for Additional Information RAI 4.2.2-1

2. STPNOC LRA Changes with Line-in/Line-out Annotations

NOC-AE-12002933 Page 3 cc:

(paper copy) (electronic copy)

Regional Administrator, Region IV A. H. Gutterman, Esquire U. S. Nuclear Regulatory Commission Kathryn M. Sutton, Esquire 1600 East Lamar Boulevard Morgan, Lewis & Bockius, LLP Arlington, Texas 76011-4511 Balwant K. Singal John Ragan Senior Project Manager Chris O'Hara U.S. Nuclear Regulatory Commission Jim von Suskil One White Flint North (MS 8B1) NRG South Texas LP 11555 Rockville Pike Rockville, MD 20852 Senior Resident Inspector Kevin Polio U. S. Nuclear Regulatory Commission Richard Pena P. O. Box 289, Mail Code: MN116 City Public Service Wadsworth, TX 77483 C. M. Canady Peter Nemeth City of Austin Crain Caton & James, P.C.

Electric Utility Department 721 Barton Springs Road C. Mele Austin, TX 78704 City of Austin John W. Daily Richard A. Ratliff License Renewal Project Manager (Safety) Alice Rogers U.S. Nuclear Regulatory Commission Texas Department of State Health Services One White Flint North (MS 011-Fl)

Washington, DC 20555-0001 Tam Tran Balwant K. Singal License Renewal Project Manager John W. Daily (Environmental) Tam Tran U. S. Nuclear Regulatory Commission U. S. Nuclear Regulatory Commission One White Flint North (MS O11F01)

Washington, DC 20555-0001

Enclosure 1 NOC-AE-1 2002933 Enclosure 1 STPNOC Clarification to Response to Request for Additional Information RAI 4.2.2-1

Enclosure 1 NOC-AE-12002933 Page 1 of 1 SOUTH TEXAS PROJECT, UNITS I AND 2 REQUEST FOR ADDITIONAL INFORMATION -

AGING MANAGEMENT, SET 13 (TAC NOS. ME4936 AND ME4937)

Reference:

STPNOC letter dated April 17, 2012 from D. W. Rencurrel to NRC Document Control Desk, "Response to Requests for Additional Information for the South Texas Project License Renewal Application Aging Management Program, Set 13 (Supplemental) and Set 15 (TAC Nos. ME4936 and ME4937)" (NOC-AE-12002830) (ML12114A231)

RAI 4.2.2-1 (059)

In the referenced letter, a revision to Sections 4.2.2 and 4.2.3 of the South Texas Project License Renewal Application was provided.

Section 4.2.2 provided discussion of the RTPTS values for both Unit 1 and Unit 2. In that discussion the limiting material was identified as the intermediate shell R1606-3 and the intermediate shell R2507-2 for Unit 1 and 2 respectively. Clarification is necessary to assure differentiation between the beltline limiting material and the overall limiting material of the Inlet Nozzle R1613-4 and Outlet Nozzle R2012-1 for Unit 1 and 2, respectively.

Section 4.2.3 provided discussion of the Cv USE values for both Unit 1 and Unit 2. In that discussion the limiting material was identified. Clarification is necessary to reflect the overall limiting material to be the intermediate shell R1606-2 for Unit 1 and the nozzle (upper) shell to intermediate shell circular weld and lower shell to lower head torus circular weld for Unit 2.

LRA Sections 4.2.2 and 4.2.3 are revised to clarify the identification of the most limiting material with the highest RTPTS values.

Enclosure 2 provides the line-in/line-out revisions to LRA Section 4.2.2 and 4.2.3.

Enclosure 2 NOC-AE-12002933 Enclosure 2 STPNOC LRA Changes with Line-in/Line-out Annotations

Enclosure 2 NOC-AE-12002933 Page 1 of 5 List of Revised LRA Sections RAI Affected LRA Section 4.2.2-1 Section 4.2.2 4.2.2-1 Section 4.2.3

Enclosure 2 NOC-AE-12002933 Page 2 of 5 4.2.2 Pressurized Thermal Shock Summary Description 10 CFR 50.61(b)(1) provides rules for protection against pressurized thermal shock (PTS) events for pressurized water reactors. Licensees are required to perform an updated assessment of the projected values of PTS reference temperature (RTPTS) whenever there is a significant change in projected values of RTPTS, or upon a request for a change in the expiration date for operation of the facility.

The license renewal rule 10 CFR 54.4(a)(3) also requires that the licensee evaluate those structures, systems, and components (SSCs) relied on in safety analyses or plant evaluations to perform a function that demonstrates compliance with the Commission's regulations for PTS.

10 CFR 50.61(c) provides two methods for determining RTPTS. These methods are also described as Positions 1 and 2 in Regulatory Guide 1.99, Radiation Embrittlement of Reactor Vessel Materials. Position 1 applies for material that does not have credible surveillance data available and Position 2 is used for material that does have two or more credible surveillance data sets available. The adjusted reference temperatures are calculated for both Positions 1 and 2 by following the guidance in Regulatory Guide 1.99 (Sections 1.1 and 2.1, respectively), using the copper and nickel content of STP beltline materials, and the EOLE fluence projections.

10 CFR 50.61(b)(2) establishes screening criteria for RTPTs as 270'F for plates, forgings, and axial welds and 300°F for circumferential welds. If the RTPTs does not exceed the PTS screening criteria, then only the reactor pressure vessel is relied on to demonstrate compliance with the 10 CFR 50.61, the PTS rule.

Analysis The original response to the issuance of the PTS rule, 10 CFR 50.61, by STP indicated that the projected RTPTs for both units do not exceed the PTS screening criteria (270°F for plates, forgings, and axial welds; and 300°F for circumferential welds), based on a 40 year, 32 EFPY life.

The most recent coupon examination results for both units show that the shift in RTNDT in plate and weld materials are in good agreement with or less than the Regulatory Guide 1.99 Revision 2 predictions for Units 1 and 2. The results demonstrate that the Regulatory Guide 1.99 predictions provide a conservative means to satisfy the requirement of 10 CFR 50.61; thus providing assurance of the reactor vessel integrity.

Enclosure 2 NOC-AE-12002933 Page 3 of 5 Unit 1 The data from the most recently withdrawn surveillance capsule, Capsule V, were deemed credible. RTPTS values were generated for beltline and extended beltline region materials of the Unit 1 reactor vessel for fluence values at EOLE (54 EFPY). The Unit 1 RTNDT results from Capsule V indicated measured mean 30 ft-lb transition temperatures of -12.17 0 F, 17.78°F, and -29.41 OF for longitudinal plate coupons, transverse plate coupons, and the weld metal respectively. The Capsule V material is from intermediate shell R1 606-2.

The RTPTS values for the Unit 1 beltline materials are provided in Table 4.2-2. The limiting beltline material for Unit 1 is the intermediate shell R1 606-3 with a projected EOLE RTPTS value of 83.6 0 F. The projected RTPTs values for EOLE meet the 10 CFR 50.61 screening criteria.

The extended beltline materials that are expected to receive fluence values greater than 1 x 1017 n/cm 2 (E>1.0 MeV) were also evaluated. The RTPTS values were shown to meet the 10 CFR 50.61 screening criteria. The fluence projections for the nozzle (upper) shell to intermediate shell circular weld and lower shell to lower head torus circular weld bound the other materials above and below the beltline.

The most limiting material for Unit 1 is the Inlet Nozzle R1613-4 with a proiected EOLE RTp-s value of 127.30 F.

Unit 2 The data from the most recently withdrawn surveillance capsule, Capsule U, war were deemed credible. RTPTS values were generated for beltline and extended beltline region materials of the Unit 2 reactor vessel for fluence values at EOLE (54 EFPY). The Unit 2 RTNDT results from Capsule U indicated measured mean 30 ft-lb transition temperatures of -

10.49 0 F, 22.23 0 F, and 5.88°F for longitudinal plate coupons, transverse plate coupons, and the weld metal respectively. The Capsule U material is from intermediate shell R2507-1.

The RTpTs values for the Unit 2 beltline materials are provided in Table 4.2-3. The limiting beltline material for Unit 2 is the intermediate shell R2507-2 with a projected EOLE RTPTS value of 63.7 0 F. The projected RTPTS values for EOLE meet the 10 CFR 50.61 screening criteria.

The extended beltline materials that are expected to receive fluence values greater than 1 x 1017 n/cm 2 (E>1.0 MeV) were also evaluated. The RTPTS values were shown to meet the 10 CFR 50.61 screening criteria. The fluence projections for the nozzle (upper) shell to intermediate shell circular weld and lower shell to lower head torus circular weld bound the other materials above and below the beltline.

The most limitingq material for Unit 2 is the Outlet Nozzle R2012-1 with a proiected EOLE RTpTs value of 111.1 OF.

Enclosure 2 NOC-AE-12002933 Page 4 of 5 Disposition: Projection, 10 CFR 54.21(c)(1)(ii)

The RTPTS values were revised with projections to the end of the period of extended operation. Therefore, these TLAAs are dispositioned in accordance with 10 CFR 54.21(c)(1)(ii).

4.2.3 Upper-Shelf Energy (USE)

Summary Description Per Regulatory Guide 1.99, Radiation Embrittlement of Reactor Vessel Materials, the Charpy upper-shelf energy (Cv USE) is assumed to decrease as a function of fluence and copper content. Figure 2 of the guide determines this magnitude of decrease when surveillance data is not used (Position 1.2). In addition, if surveillance data is to be used (Position 2.2), the decrease in upper shelf energy may be obtained by plotting the reduced plant surveillance data on Figure 2 of the guide and fitting the data with a line drawn parallel to the existing lines as the upper bound of all the data. This line can then be used in preference to the existing line. The Cv USE can be predicted using the corresponding %T fluence projection, the copper content of the beltline materials, and the results of the capsules tested to date using Figure 2 of the guide. The fluence at the 1/4T depth (f) is determined using the clad / base metal fluence (f&s-_4) and the depth of the desired location in inches.

10 CFR 50, Appendix G, Section IV.A.1.a requires that the reactor vessel beltline materials must have a Cv USE of no less than 75 ft-lb initially, and must maintain Cv USE throughout the life of the vessel of no less than 50 ft-lb unless it is demonstrated in a manner approved by the Director, Office of Nuclear Reactor Regulation, that lower values of Cv USE will provide margins of safety against fracture equivalent to those required by ASME Section XI, Rules for In-Service Inspection of Nuclear Power Plant Components, Appendix G.

Analysis The most recent coupon examination results for both units show that the decline in Cv USE in plate and weld materials are less than originally predicted by Regulatory Guide 1.99 Revision 2 for Units 1 and 2. The results demonstrate that the Regulatory Guide 1.99 predictions provide a conservative means to satisfy the requirements of 10 CFR 50, Appendix G; thus providing assurance of the reactor vessel integrity.

Unit I The Cv USE results from Unit 1 surveillance Capsule V indicated a mean Charpy V-notch Cv USE of 131 ft-lbf, 106 ft-lbf and 86 ft-lbf for longitudinal plate coupons, transverse plate coupons, and the weld metal respectively. The data were determined to be credible, however the data were not included in the EOLE Cv USE projections.

To support operation during the period of extended operation, these values were projected to 54 EFPY of operation. The EOLE Cv USE values for the Unit 1 belt"Re reactor vessel

Enclosure 2 NOC-AE-12002933 Page 5 of 5 materials are provided in Table 4.2-4. The limiting value was 71 ft-lbf for intermediate shell R1606-2.

The extended beltline nozzle and shell materials that are expected to receive fluence values greater than 1 x 1017 n/cm 2 (E>1.0 MeV) were also evaluated and confirm an EOLE Cv USE that is greater than 50 ft-lbf. The ftueRe embrittlement projections for the Ie (-upp shell to intermediate shell circulair weld and lower shell to lower head torus circ'u!ar weld intermediate shell R1606-2 bounds the other materials above and below the beltline.

Unit 2 The Cv USE results from Unit 2 surveillance Capsule U indicated a mean Charpy V-notch Cv USE of 138 ft-lbf, 98 ft-lbf, and 97 ft-lbf for longitudinal plate coupons, transverse plate coupons, and the weld metal respectively. The Surveillance Capsule U results for Unit 2 were deemed credible, however the data were not included in the EOLE Cv USE projections.

To support operation during the period of extended operation, these values were projected to 54 EFPY of operation. The EOLE Cv USE values for the Unit 2 beltUie reactor vessel materials are provided in Table 4.2-5. The limiting value was -7 72 ft-lbf for lowe-shel longitudinal weld E3.12 the nozzle (upper) shell to intermediate shell circular weld and lower shell to lower head torus circular weld.

The extended beltline nozzle and shell materials that are expected to receive fluence values greater than 1 x 1017 n/cm 2 (E>1.0 MeV) were also evaluated and confirm an EOLE Cv USE that is greater than 50 ft-lbf. The bottom head torus, R3920 1, .A.s 4dentified to have a projected EGLE rV USE value of 76 ftlbf. The RT is6 m ore ImitiRg than the beltline maeral HwGever the (CVUSE still meets the FIR 50, Appendix G 540 ft Ibf criterion.

The embrittlement fhueRee-projections for the nozzle (upper) shell to intermediate shell circular weld and lower shell to lower head torus circular weld bound the other materials above and below the beltline.

Disposition: Projection, 10 CFR 54.21(c)(1)(ii)

The Cv USE values were re-evaluated with projections to the end of the period of extended operation. Therefore, these TLAAs are dispositioned in accordance with 10 CFR 54.21(c)(1)(ii). The re-evaluations demonstrated that the Cv USE in the limiting material of each unit will remain above the 10 CFR 50 Appendix G acceptance criteria of 50 ft-lbf.