RS-11-094, Units 1 and 2 - Supplement to the Third 10-Year Inservice Inspection Interval Requests for Relief for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations

Units 1 and 2 - Supplement to the Third 10-Year Inservice Inspection Interval Requests for Relief for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations

ML111650286
Person / Time
Site:	Byron, Braidwood
Issue date:	06/14/2011
From:	Hansen J Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-11-094
Download: ML111650286 (14)

Text

Nuclear 10 CFR 50.55a RS-11-094 June 14, 2011 U. S. Nuclear Regulatory Commission AnN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating license Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating license Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Supplement to the Third 10-Year Inservice Inspection Interval Requests for Relief for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations

References:

(1) Letter from J. L. Hansen (EGG) to U. S. NRC, "Third 10-Year Inservice Inspection Interval Requests for Relief for Atlernative Requirements for the Repair of Reactor Vessel Head Penetrations," dated April 19, 2011, ADAMS Accession No. ML111100620 (2) Letter from N. DiFrancesco, (U. S. NRC) to M. J. Pacilio, (EGC),

"Unacceptable with Opportunity to Supplement RE: Alternatives to the ASME Code Requirements for Repairs to the Reactor Vessel Head Penetrations (TAC Nos. ME6071, ME6072, ME6073, and ME6074)," dated June 6, 2011, ADAMS Accession No. ML111330653 In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (a)(3)(i), Exelon Generation Company, LLC (EGC), submitted relief requests (RRs) 13R-20 for Byron Station, Units 1 and 2, and 13R-09 for Braidwood Station, Units 1 and 2, (Le., Reference 1). The RRs proposed an alternative repair technique using weld overlays on the reactor vessel head penetration housing and J-groove welds, using a Westinghouse embedded flaw repair method.

EGC proposed the alternative for indications that may be encountered in the future, and that may be the result of primary water stress corrosion cracking (PWSCG). Embedding a flaw within PWSCC resistant materials (Le., Alloy 52 weld metal) will assure structural integrity of the nozzles.

In Reference 2, the NRC provided results of the acceptance review of the relief request. The NRC concluded that information is needed prior to a decision on the acceptability and to enable the NRC to begin its detailed technical review. Attachment 1 to this letter contains the questions from the NRC, along with a discussion of the response. EGC and the NRC held a teleconference on June 1, 2011, to reach a common understanding of the requested

June 14, 2011 U. S. Nuclear Regulatory Commission Page 2 information. A revision to the RRs is provided in Attachment 2 of this letter that is consistent with the response to the NRC questions in Attachment 1.

There are no regulatory commitments contained in this submittal. If you have any questions about this letter, please contact Mr. Richard W. Mcintosh at (630) 657-2816.

Attachments:

1. Response to Supplemental Information Request

2. 10 CFR 50.55a Relief Requests 13R-09 and 13R-20, Revision 1 Page 2 of 2

ATTACHMENT 1 Response to Supplemental Information Request NRC REQUEST (Le., Reference 2)

(1)

Compliance with the ASME Code requires that mechanical defects for the subject seal weld are repaired according to Section III, NB-4450. The requirements of NB-4450 ensure that flaws are completely removed from the weld material. Provide a basis for the definition of a mechanical discontinuity within the subject RR.

(a) Provide a sizing technique for this type of defect and documentation of its demonstrated performance.

(b) Provide a qualified volumetric technique and documentation of its demonstrated performance to accurately depth size and characterize mechanical discontinuities in seal welds for the entire area of coverage of the seal weld over al/ reactor vessel head penetration nozzle angles.

(c) Provide a qualification plan to demonstrate the performance of equipment, personnel and procedures to implement the techniques of (a) and (b) above.

(2)

Provide a basis for assurance that a mechanical discontinuity will be re-consumed with additional weld metal as described in Section 5.1.3 of the proposed relief.

Demonstration that these mechanical discontinuities are re-consumed is to ensure that indications are removed and that latent welding defects do not emerge during future operating cycles.

(a) Demonstrate through mockups the amount of weld material needed to be deposited to re-consume aI/ possible mechanical discontinuities in seal welds for the entire area of coverage of the seal weld over aI/ reactor vessel head penetration nozzle angles. Additional/y, please provide a summary table of number of required weld beads and area of coverage requirements to ensure re-consumption.

(b) Provide a qualified volumetric inspection program which will be capable of ensuring the original defect is re-consumed for the entire area of coverage of the seal weld over aI/ reactor vessel head penetration nozzle angles.

(c) Provide a qualification plan to qualify equipment, personnel and procedures to perform (a) and (b) above.

(3)

The NRC would review the request to re-consume mechanical discontinuities under the provisions for providing an acceptable level of quality and safety, as opposed to a hardship or unusual difficulty. As such, the NRC will require a basis for equivalent structural integrity of re-consumed mechanical discontinuities to that achieved through compliance with aI/ American Society of Mechanical Engineers,Section III, requirements for application of the weld material.

Page 1 of 2

ATTACHMENT 1 Response to Supplemental Information Request

RESPONSE

The revision to the Relief Requests (RRs) provided in Attachment 2 removes those provisions that are applicable to the supplemental information requested above. Consequently, the specific information requested is no longer applicable to the proposal. Revision 1 in makes the following changes to Revision 0, (Le., Reference 1), of the RRs:

(a) Clarified Section 3.0, "Applicable Code Requirement," at the header for "Weld Metal Defect Repairs," to show that this information is relevant to the J-Groove weld.

(b) Deleted the content of Section 5.1.3, that discussed provisions applicable to mechanical discontinuities detected by a surface examination in the seal weld during installation.

(c) Removed the fifth paragraph under Section 5.2, "Technical Basis for Proposed Alternative," that discussed provisions for the deposit of additional Alloy 52 or 52M weld bead(s) to consume all or most of the mechanical discontinuities identified in the seal weld during installation.

Considering the above changes, Revision 1 does not contain a provision for the use of an alternative to ASME Code requirements of NB-4450 for the repair of defects encountered in the subject seal welds during installation.

Another change is made in Revision 1 that is unrelated to the questions, is not technical and improves readability. This change is at Section 5.1.2, subpart 2, item f, under the second bulleted item.. This item describes the seal weld that will be used to repair an outside diameter (00) flaw in the nozzles and the J-groove weld. The "at least" word pairing is inserted before the phrase "three (3) layers of Alloy 52... ". This change remains consistent with the description of the repair.

REFERENCES (1) Letter from J. L. Hansen (Exelon) to U. S. NRC, "Third 10-Year Inservice Inspection Interval Requests for Relief for Atlernative Requirements for the Repair of Reactor Vessel Head Penetrations," dated April 19, 2011, ADAMS Accession No. ML111100620 (2) Letter from N. DiFrancesco, (U. S. NRC) to M. J. Pacilio, (EGC), "Unacceptable with Opportunity to Supplement RE: Alternatives to the ASME Code Requirements for Repairs to the Reactor Vessel Head Penetrations (TAC Nos. ME6071, ME6072, ME6073, and ME6074)," dated June 6,2011, ADAMS Accession No. ML111330653 Page 2 of 2

ATTACHMENT 2 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 1

lSI Program Plan Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 1 of 9)

Request for Relief Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 50.55a(a}(3)(i}

1.0 ASME CODE COMPONENT'S) AFFECTED Component Numbers Braidwood and Byron Station, Units 1 and 2, Reactor Vessels 1 RC01 R (Unit 1) and 2RC01 R (Unit 2)

==

Description:==

Alternative Requirements for the Repair of Reactor Vessel Head Penetrations (VHPs) and J-groove Welds Code Class:

Class 1 Examination Category:

ASME Code Case N-729-1 Code Item:

B4.20 Identification:

Byron Units 1 and 2, VHP Numbers 1 through 78, (P-1 through P-78)

Drawing Numbers:

Previous repairs (13R-14): P-68 (13R-19): P-31, P-43, P-64, and P-76 Braidwood Units 1 and 2, VHP Numbers 1 through 78, (P-1 through P-78)

Various 2.0 APPLICABLE CODE EDITION AND ADDENDA Inservice Inspection and Repair/Replacement Programs: American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, 2001 Edition, through 2003 Addenda. Examinations of the VHPs are performed in accordance with 10 CFR SO.SSa(g)(6)(ii)(D), which specifies the use of Code Case N-729-1, with conditions.

Code of Construction [Reactor Pressure Vessel (RPV)]: ASME Section III, 1971 Edition through summer 1973 Addenda.

3.0 APPLICABLE CODE REQUIREMENT IWA-4000 of ASME Section XI contains requirements for the removal of defects from and welded repairs performed on ASME components. The specific Code requirements for which use of the proposed alternative is being requested are as follows:

lSI Program Plan Units 1 and 2, Third Interval 10 CFR SO.SSa RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 2 of 9)

ASME Section XI, IW A-4421 states:

Defects shalJ be removed or mitigated in accordance with the following requirements:

(a)

Defect removal by mechanical processing shall be in accordance with IWA-4462.

(b)

Defect removal by thermal methods shall be in accordance with IWA-4461.

(c)

Defect removal or mitigation by welding or brazing shall be in accordance with IWA-4411.

(d)

Defect removal or mitigation by modification shall be in accordance with IWA-4340.

Note that use of the "Mitigation of Defects by Modification" provisions of IWA-4340 is prohibited per 10 CFR 50.55a(b)(2)(xxv).

For the removal or mitigation of defects by welding, ASME Section XI, IWA-4411 states, in part, the following.

Welding, brazing, and installation shall be performed in accordance with the Owner's Requirements and... in accordance with the Construction Code of the item...

The applicable requirements of the Construction Code required by IWA-4411 for the removal or mitigation of defects by welding from which relief is requested are as follows.

Base Material Defect Repairs:

For defects in base material, ASME Section III, NB-4131 requires that the defects are eliminated, repaired, and examined in accordance with the requirements of NB-2500.

These requirements include the removal of defects via grinding or machining per NB-2538. Defect removal must be verified by a Magnetic Particle (MT) or Liquid Penetrant (PT) examination in accordance with NB-2545 or NB-2546, and if necessary to satisfy the design thickness requirement of NB-3000, repair welding in accordance with NB-2539.

ASME Section III, NB-2539.1 addresses removal of defects and requires defects to be removed or reduced to an acceptable size by suitable mechanical or thermal methods.

ASME Section III, NB-2539.4 provides the rules for examination of the base material repair welds and specifies they shall be examined by the MT or PT methods in accordance with NB-2545 or NB-2546. Additionally, if the depth of the repair cavity exceeds the lesser of 3/8-inch or 10% of the section thickness, the repair weld shall be examined by the radiographic method in accordance with NB-511 0 using the acceptance standards of NB-5320.

Weld Metal Defect Repairs (This applies to the CRDM penetration J-Groove weld.)

ASME Section III, NB-4450 addresses repair of weld metal defects.

lSI Program Plan Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 3 of 9)

ASME Section III, NB-4451 states; that unacceptable defects in weld metal shall be eliminated and, when necessary, repaired in accordance with NB-4452 and NB-4453.

ASME Section III, NB-4452 addresses elimination of weld metal surface defects without subsequent welding and specifies defects are to be removed by grinding or machining.

ASME Section III, NB-4453.1 addresses removal of defects in welds by mechanical means or thermal gouging processes and requires the defect removal to be verified with MT or PT examinations in accordance with NB-5340 or NB-5350 and weld repairing the excavated cavity. In the case of partial penetration welds where the entire thickness of the weld is removed, only a visual examination is required to determine suitability for re-welding.

As an alternative to the requirements above, repairs will be conducted in accordance with the appropriate edition/addenda of ASME Section III and the alternative requirements, based on WCAP-15987-P, Revision 2-P-A, "Technical Basis for the Embedded Flaw Process for Repair of Reactor Vessel Head Penetrations,"

December 2003, (Refer to Reference 1, hereafter known as WCAP-15987-P).

4.0 REASON FOR THE REQUEST Exelon Generation Company, LLC (EGC) will conduct examinations of the reactor Vessel Head Penetrations (VHPs) in accordance with Code Case N-729-1, as amended by 10 CFR 50.55a. Flaw indications that require repair may be found on the VHP tube material and/or the J-groove attachment weld(s} on the underside of the reactor vessel head.

Relief is requested from the requirements of ASME Section XI, IWA-4411 to perform permanent repair of future defects that may be identified on the VHP's and/or J-groove attachment weld(s} in accordance with the rules of the ASME Section III Construction Code as described in this relief request.

Specifically, relief is requested from:

The requirements of ASME Section III, NB-4131, NB-2538, and NB-2539 to eliminate and repair defects in materials.

The requirements of ASME Section III, NB-4450 to repair defects in weld metal.

5.0 PROPOSED ALTERNATIVE AND BASIS FOR USE 5.1 Proposed Alternative EGC proposes to use the less intrusive embedded flaw process (Reference 1) for the repair of VHP(s} as approved by the NRC (Reference 2) as an alternative to the defect removal requirements of ASME Section XI and Section III.

lSI Program Plan Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R*20 Revision 1 (Page 4 of 9) 5.1.1 The criteria for flaw evaluation established in 10 CFR 50.55a(g)(6)(ii)(D), which specifies the use of Code Case N-729-1, will be used in lieu of the "Flaw Evaluation Guidelines" specified by the NRC Safety Evaluation for WCAP-15987 -P (Refer to Reference 5).

5.1.2 Consistent with WCAP-15987 -P, Revision 2-P-A methodology, the following repair requirements will be performed.

1. Inside Diameter (10) VHP Repair Methodology

a. An unacceptable axial flaw will be first excavated (or partially excavated) to a maximum depth of 0.125 inches. Although this depth differs from that specified in WCAP-15987-P, the cavity depth is not a critical parameter in the implementation of a repair on the 10 surface of the VHP. The goal is to isolate the susceptible material from the primary water (PW) environment. The purpose of the excavation is to accommodate the application of at least two (2) weld layers of Alloy 52 or 52M, which is resistant to Primary Water Stress Corrosion Cracking (PWSCC), to meet that requirement. The depth specified in WCAP-15987-P is a nominal dimension and the depth needed to accommodate three weld layers while still maintaining the tube 10 dimension. Since two (2) weld layers will be applied, less excavation is required and only 0.125 inches of excavation is necessary. The shallower excavated cavity for 2 weld layers would mean a slightly thinner weld, which would produce less residual stress.

The excavation will be performed using an Electronic Discharge Machining (EDM) process to minimize VHP tube distortion. After the excavation is complete, either an ultrasonic test (UT) or surface examination will be performed to ensure that the entire flaw length is captured. Then a minimum of 2 layers of Alloy 52 or 52M weld material will be applied to fill the excavation. The expected chemistry of the weld surface is that of typical Alloy 52 or 52M weldment with no significant dilution. The finished weld will be conditioned to restore the inside diameter and then examined by UT and surface examination to ensure acceptability.

b. If required, unacceptable 10 circumferential flaw will be either repaired in accordance with existing code requirements; or will be partially excavated to reduce the flaw to an acceptable size, examined by UT or surface examination, inlaid with Alloy 52 or 52M, and examined by UT and surface examination as described above.

2. Outside Diameter (00) VHP and J-groove Weld Repair Methodology

a. An unacceptable axial or circumferential flaw in a tube below a J-groove attachment weld will be sealed off with an Alloy 52 or 52M weldment. Excavation or partial excavation of such flaws is not necessary. The embedded flaw repair technique may be applied to 00 axial or circumferential cracks below the J-groove weld because they are located away from the pressure boundary, and the proposed repair of sealing the crack with Alloy 690 weld material would isolate the crack from the environment as stated in Section 3.6.1 of the NRC Safety Evaluation for WCAP-15987 -P.

lSI Program Plan Units 1 and 2, Third Interval 10 CFR SO.SSa RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 5 of 9)

b. Unacceptable radial flaws in the J-groove attachment weld will be sealed off with a 360 degree seal weld of Alloy 52 or 52M covering the entire weld. Excavation or partial excavation of such flaws is not necessary.

c. If EGC determines an excavation is desired (e.g., boat sample), then The excavation will be filled with Alloy 52 or 52M material.

It is expected that a portion of the indication may remain after the boat sample excavation; however, a surface examination will be performed on the excavation to assess the pre-repair condition.

Depending on the extent and/or location of the excavation, the repair procedure requires the Alloy 52 or 52M weld material to extend at least one half inch outboard of the Alloy 82/182 to stainless steel clad interface.

d. Unacceptable axial flaws in the VHP tube extending into the J-groove weld will be sealed with Alloy 52 or 52M as discussed in Item 5.1.2.2.a above. In addition, the entire J-groove weld will be sealed with Alloy 52 or 52M to embed the axial flaw. The seal weld will extend onto and encompass the portion of the flaw on the outside diameter of the VHP tube.

e. For seal welds performed on the J-groove weld, the interface boundary between the J-groove weld and stainless steel cladding will be located to positively identify the weld clad interface to ensure that all of the Alloy 82/182 material of the J-groove weld is seal welded during the repair.

f.

The seal weld that will be used to repair an 00 flaw in the nozzles and the J-groove weld will conform to the following.

Prior to the application of the Alloy 52 or 52M seal weld repair on the RPV clad surface, at least three beads (one layer) of ER309L stainless steel buffer will be installed 360 0 around the interface of the clad and the J-groove weld metal.

The J-groove weld will be completely covered by at least three (3) layers of I Alloy 52 or 52M deposited 360 0 around the nozzle and over the ER309L stainless steel buffer. Additionally, the seal weld will extend onto and encompass the outside diameter of the penetration tube Alloy-600 material by at least one half inch.

The VHP tube will have at least two (2) layers of Alloy 52 or 52M deposited over the flaw on the VHP tube, extending out at least one half inch beyond the flaw, or to the maximum extent allowed by the nozzle geometry (e.g.,

limited length of the VHP tube).

lSI Program Plan Units 1 and 2, Third Interval 10 CFR SO.SSa RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 6 of 9)

g. Nondestructive examinations of the finished seal weld repair (Le., Repair NDE) and during subsequent outages (Le., lSI NDE) are summarized in the table below.

Repair Location in Flaw Orientation Repair Repair NDE lSI NDE Original in Original Component Component Method Note (2)

Note (2)

VHP Nozzlerrube 10 Axial or Seal weld UTand UT or Surface Ci rcumferential Surface VHP Nozzlerrube Axial or 00 above J-groove Circumferential Note (1)

Note (1)

Note (1) weld VHP Nozzlerrube Axial or 00 below J-groove Circumferential Seal weld UT or Surface UT or Surface weld UTand UT and Surface, J-groove weld Axial Seal weld

Surface, Note (3)

Note (3)

UT and UT and Surface, J-groove weld Circumferential Seal weld

Surface, Note (3)

Note (3)

Notes:

(1) Repair method to be approved separately by NRC.

(2) Preservice and Inservice Inspection to be consistent with 5.1.3 Deleted 10 CFR 50.55a(g)(6)(ii)(D), which requires implementation of Code Case N-729-1 with conditions.

(3) UT personnel and procedures qualified in accordance with 10 CFR 50.55a(g)(6)(ii)(D), which requires implementation of Code Case N-729-1 with conditions. Examine the accessible portion of the J-groove repaired region. The UT plus surface examination coverage equals to 100%.

5.1.4 Reporting Requirements and Conditions on Use EGC will notify NRC of the Division of Component Integrity or its successor of changes in indication(s) or findings of new indication(s) in the penetration nozzle or J-groove weld beneath a seal weld repair, or new linear indications in the seal weld repair, prior to commencing repair activities in subsequent outages.

lSI Program Plan Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 7 of 9) 5.2 Technical Basis for Proposed Alternative As discussed in WCAP-15987-P, the embedded flaw repair technique is considered a permanent repair. As long as a PWSCC flaw remains isolated from the Primary Water (PW) environment, it cannot propagate. Since an Alloy 52 or 52M weldment is considered highly resistant to PWSCC, a new PWSCC flaw should not initiate and grow through the Alloy 52 or 52M seal weld to reconnect the PW environment with the embedded flaw. Structural integrity of the affected J-groove weld and/or nozzle will be maintained by the remaining unflawed portion of the weld and/or the VHP. Alloy 690 and Alloy 52/52M are highly resistant to stress corrosion cracking, as demonstrated by multiple laboratory tests, as well as over ten years of service experience in replacement steam generators.

The residual stresses produced by the embedded flaw technique have been measured and found to be relatively low because of the small seal weld thickness. This implies that no new flaws will initiate and grow in the area adjacent to the repair weld. There are no other known mechanisms for significant flaw propagation in the reactor vessel head closure head and penetration tube region since cyclic loading is negligible, as described in WCAP-15987-P. Therefore, fatigue driven crack growth should not be a mechanism for further crack growth after the embedded flaw repair process is implemented.

The thermal expansion properties of Alloy 52 or 52M weld metal are not specified in the ASME Code. In this case the properties of the equivalent base metal (Alloy 690) should be used. For Alloy 690, the thermal expansion coefficient at 600 degrees F is 8.2E-6 in/in/degree F as found in Section II part D. The Alloy 600 base metal has a coefficient of thermal expansion of 7.8E-6 in/in/degree F, a difference of about 5 percent. The effect of this small difference in thermal expansion is that the weld metal will contract more than the base metal when it cools, thus producing a compressive stress on the Alloy 600 tube or J-groove weld. This beneficial effect has already been accounted for in the residual stress measurements reported in the technical basis for the embedded flaw repair, as noted in the WCAP-15987-P.

WCAP-16401-P, Revision 0 (Reference 3) provides the plant-specific analysis performed for Byron and Braidwood Stations using the same methodology as WCAP-15987-P. This analysis provides the means to evaluate a broad range of postulated repair scenarios to the reactor vessel head penetrations and J-groove welds relative to ASME Code requirements for allowable size and service life.

The above proposed embedded flaw repair process is supported by applicable generic and plant specific technical bases, and is therefore considered to be an alternative to Code requirements that provides an acceptable level of quality and safety, as required by 10 CFR 50.55a(a)(3)(i).

lSI Program Plan Units 1 and 2, Third Interval 10 CFR SO.SSa RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 8 of 9) 6.0 DURATION OF THE PROPOSED ALTERNATIVE The duration of the proposed alternative is for the remainder of the Byron Station Units 1 and 2, Third Inservice Inspection Interval currently scheduled to end in July 15, 2016.

The duration of the proposed alternative is for the remainder of the Braidwood Units 1 and 2, Third Inservice Inspection Interval currently scheduled to end in July 28, 2018, and October 16, 2018, respectively.

7.0 PRECEDENTS In Reference 2, the NRC generically approved the embedded flaw repair process described in Reference 1. Requests to use the embedded flaw technique to repair cracks on the 00 of VHPs as well as to repair flaws in the J-groove attachment welds of VHPs have been previously approved by the NRC on a plant specific basis. The NRC approved a similar repair for Byron Station Unit 2 in Reference 9. On March 28, 2011, Byron Station Unit 1 received verbal authorization for use of the seal weld repairs methodology on P-64 and P-76, and again on April 10, 2011, for P-31 and P-43 (References 10 and 11).

This alternative incorporates lessons that are learned regarding the significant radiation dose incurred for seal weld repair surface examinations at Beaver Valley, Unit 2, during the fall 2009 outage repair activities, which were discussed in the previously approved 10 CFR 50.55a request for Beaver Valley, Unit 2 (Reference 8). As such, this alternative requests provisions that permit original construction code acceptance criteria for the post weld overlay surface examination, and a barrier layer of ER309L filler material, prior to the application of three Alloy 52M repair weld layers on the clad surface, at the periphery of the weld overlay (at the repair-to-clad interface).

lSI Program Plan Units 1 and 2, Third Interval 10 CFR SO.SSa RELIEF REQUESTS 13R-09 and 13R-20 Revision 1 (Page 9 of 9)

8.0 REFERENCES

1. Westinghouse WCAP-15987-P, Revision 2-P-A, "Technical Basis for the Embedded Flaw Process for Repair of Reactor Vessel Head Penetrations," December 2003

2. Letter from H. N. Berkow (U. S. NRC) to H. A. Sepp (Westinghouse Electric Company), "Acceptance for Referencing - Topical Report WCAP-15987-P, Revision 2, 'Technical Basis for the Embedded Flaw Process for Repair of Reactor Vessel Head Penetrations,' (TAC NO. MB8997)," dated July 3, 2003

3. Westinghouse WCAP-16401-P, Revision 0, "Technical Basis for Repair Options for Reactor Vessel Head Penetration Nozzles and Attachment Welds: Byron and Braidwood Units 1 and 2," March 2005

4. Letter LTR-NRC-03-61 from J. S. Galembush (Westinghouse Electric Company) to Terence Chan (U. S. NRC) and Bryan Benney (U.S. NRC), "Inspection of Embedded Flaw Repair of a J-groove Weld," dated October 1,2003

5. Letter from R. J. Barrett (U. S. NRC) letter to A. Marion (Nuclear Energy Institute),

"Flaw Evaluation Guidelines," dated April 11, 2003

6. Byron Station, Unit No.2 - Relief Request 13R-14 for the Evaluation of Proposed Alternatives for Inservice Inspection Examination Requirements (TAC NO. MD5230)

7. American Society of Mechanical Engineers Boiler and Pressure Vessel Case N-729-1, "Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles Having Pressure-Retaining Partial-Penetration WeldsSection XI, Division 1"

8. Letter from N. L. Salgado (U. S. NRC) to P. A. Harden (FirstEnergy), "Beaver Valley Power Station, Unit No.2 - Relief Request Regarding an Alternative Weld Repair Method for Reactor Vessel head Penetrations J-Groove Welds (TAC No. ME4176),"

Request 2-TYP-3-RV-03, February 25,2011 (ADAMS Accession No. ML110470557)

9. Letter from R. Gibbs (U. S. NRC) to C. M. Crane (EGC), "Byron Station, Unit No.2 -

Relief Request 13R-14 for the Evaluation of Proposed Alternatives for Inservice Inspection Examination Requirements (TAC No. MD5230)," dated May 23,2007

10. NRC Memorandum, "Byron Station, Unit No.1 - Verbal Authorization of Relief Request 13R Alternative Requirements for Repair of Reactor Vessel Head Penetrations 64 and 76 (TAC No. ME5877)," dated March 29, 2011

11. NRC Memorandum, "Byron Station Unit No.1 - Verbal Authorization of Relief Request 13R Alternative Requirements for Repair of Reactor Vessel Head Penetrations Nos. 31 and 43 (TAC No. ME5948)," dated April 13, 2011