Text

Revised Relief Request for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations
	ML15309A227
Person / Time
Site:	Byron, Braidwood
Issue date:	11/05/2015
From:	Gullott D; Exelon Generation Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	RS-15-234
	Download: ML15309A227 (13)
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10 CFR 50.55a RS-15-234 November 5, 2015 U. S. Nuclear Regulatory Commission ATTN: 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:

Revised Relief Request for Braidwood and Byron Stations Alternative Requirements for the Repair of Reactor Vessel Head Penetrations

References:

(1) Letter from David M. Gullott, (EGC) to U.S. NRC, "Revision to the Third 10-Year Inservice Inspection Interval Requests for Relief for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations," Dated September 8, 2014, ADAMS Accession No. ML14251A536 (2)

Email from Joel Wiebe, (U. S. NRC) to Jessica Krejcie, (EGO),

"Preliminary RAI Regarding Braidwood and Byron Stations Relief Request for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations," Dated March 23, 2015 (3)

Letter from David M. Gullott, (EGC) to U.S. NRC, "Response to Preliminary RAI Regarding Braidwood and Byron Stations Relief Request for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations," Dated May 29, 2015 In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (a)(3)(i), in a letter dated September 8, 2014, (Reference 1), Exelon Generation Company, LLC (EGC) submitted a revision to the Third 10-Year lnservice Inspection Interval Requests for Relief for Alternative Requirements for the Repair of Reactor Vessel Head Penetrations at Braidwood Station, Units 1 and 2 and Byron Station, Units 1 and 2. The submitted letter requested inspection frequency relief for the Reactor Vessel Head Penetrations repair weld surface examinations (i.e., dye penetrant (PT)).

In Reference 2, the NRC requested additional information (RAI) related to its review of Reference 1. The additional information was discussed in a teleconference with the NRC on April 24, 2015. During this teleconference it was identified that EGC would submit a revision to the relief request that would reduce the frequency of PT examinations in lieu of elimination of the PT examinations. In Reference 3, Exelon responded to the Reference 2 RAI, provided a revised relief request, and provided a revision to the supporting technical information.

November 5, 2015 U.S. Nuclear Regulatory Commission Page 2 The NRC requested clarification on the information provided in Reference 3, and a teleconference was held with the NRC on August 6, 2015. During this teleconference, Exelon clarified information provided and discussed a revision to the Reference 3 Relief Request. Attachment 1 contains the newly revised Relief Request.

Reference 3 Attachment 3 (proprietary) and Attachment 4 (non-proprietary) provides the supporting technical information for this request. Since submittal of the Reference 3 technical evaluation, additional PT examination data was gathered during the Byron Station refueling outage in Fall 2015 (131 R20). Penetration 31 (P31) had one rejectable linear indication and one rejectable rounded indication. The linear indication was repaired with buffing only while the rounded indication was repaired using both buffing and welding. Penetration 43 (P43) had no rejectable indications.

No buffing or welding was required to P43. The total dose to initially examine both penetrations was 1.935 Rem and the additional dose to buff and weld P31 was approximately 5.256 Rem. This information supplements the information contained in Table 2 of Reference 3 Attachment 3 (proprietary) and Attachment 4 (non-proprietary).

EGC originally requested approval of this proposed relief request by September 4, 2015, prior to the beginning of the Byron Station refueling outage in Fall 2015 (131 R20). However, the revised proposed Relief Request would first provide benefit during the Byron Station refueling outage in Spring 2016 (B2R1 9). Therefore, approval of this revised proposed relief request is requested by April 15, 2016, prior to the beginning of B2R19.

There are no regulatory commitments contained in this submittal.

If you have any questions regarding this matter, please contact Jessica Krejcie at (630) 657-2816.

Respectfully, David M. Gullott Manager - Licensing Exelon Generation Company, LLC : 10 CFR 50.55a Relief Requests 13R-09 and 13R-20, Revision 2 Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 50.55a(z)(1) (Non-Proprietary) cc:

Regional Administrator-NRC Region Ill NRC Senior Resident Inspector-Braidwood Station NRC Senior Resident Inspector-Byron Station NRC Project Manager, NRR - Braidwood and Byron Station Illinois Emergency Management Agency - Division of Nuclear Safety 10 CFR 50.55a RELIEF REQUESTS 1313-09 and 13R-20, Revision 2 Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 5055a(z)(1)

IS! Program Plan -

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

Request for Relief Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 50.55a(z)(1) 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 (VHP5) 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-i through P-78)

Previous repairs (13R-14): Unit 2, P-68 (13R-19): Unit 1, P-31, P-43, P-64, and P-761 (I3R-20): Unit 2, P-61 Braidwood Units I and 2, VHP Numbers 1 through 78, (P-i through P-78)

Previous repairs (I3R-09) Unit 1, P-691 Drawing Numbers:

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 50.55a(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.

1 This relief request includes Inservice Inspection (ISI) examination requirements for repairs previously completed in accordance with 13R-1 4, 13R-19, I3R-09 and 13R-20.

IS! Program Plan

Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and I3R-20 Revision 2 (Page 2 of 10) 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:

ASME Section Xl, IWA-4421 states:

Defects shall 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-441 1.

(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 Xl, IWA-441 1 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-441 1 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 N13-3000, 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 Ill, 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-51 10 using the acceptance standards of NB-5320.

IS! Program Plan

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

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

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

ASME Section Ill, 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 Ill, 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-1 5987-F, 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-1 5987-F).

4.0

REASON FOR THE REQUEST Exelon Generation Company, LLC (EGC) will conduct examinations of the reactor Vessel Head Penetrations (VHP5) 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 VHF 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-441 I to perform permanent repair of future defects that may be identified on the VHF's and/or J-groove attachment weld(s) in accordance with the rules of the ASME Section Ill 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.

ISI Program Plan

Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 2 (Page 4 of 10) 5.0

PROPOSED ALTERNATIVE AND BASIS FOR USE 5.1

Proposed Alternative EGO 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.

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-1 5987-P (Refer to Reference 5).

5.1.2 Consistent with WCAP-1 5987-F, Revision 2-P-A methodology, the following repair requirements will be performed.

1. Inside Diameter (ID) VHF 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 ID surface of the VHF. 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-1 5987-P is a nominal dimension and the depth needed to accommodate three weld layers while still maintaining the tube ID 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 ii;ciii ci slightly 1JIIIUItI WIU, WIHLII WUUIU fUUUL IJUUJ SUS.

The excavation will be performed using an Electrical Discharge Machining (EDM) process to minimize VHF 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 ID 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 (OD) VHF and J-groove Weld Repair Methodology

IS! Program Plan

Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 2 (Page 5 of 10)

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 OD 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-1 5987-P.

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 Er

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 OD 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 3600 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 Alloy 52 or 52M deposited 360° 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.

IS! Program Plan

Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 2 (Page 6 of 10)

The VHP tube will have at least two (2) layers of Alloy 52 or 52M deposited over the flaw on the VHF 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 VHF tube).

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

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

Note (2)

Component Component VHF Nozzle/Tube ID Axial or Circumferential Seal weld UT and Surface UT or Surface VHF Nozzle/Tube Axial or OD above J-groove Circumferential Note (1)

Note (1)

Note (1) weld VHF Nozzle/Tube Axial or OD below J-groove Circumferential Seal weld UT or Surface UT or Surface weld UT and UT and Surface, J-groove weld Axial Seal weld

Surface, Notes (3) and (4)

Note (3)

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

Surface, Notes (3) and (4)

Note _(3)

Notes:

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

(2) Freservice and Inservice Inspection to be consistent with 10 CFR 50.55a(g)(6)(ii)(D), which requires implementation of Code Case N-729-1 with conditions; or NRC-approved alternatives to these specified 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%.

(4) Surface examination of the embedded flaw repair (EFR) shall be performed to ensure the repair satisfies ASME Section Ill, NB-5350 acceptance standards. The frequency of examination shall be as follows:

a. Perform surface examination during the first and second refueling outage after installation or repair of the EFR.

b. When the examination results in 4.a above verify acceptable results then re-inspection of the EFR will be continued at a frequency of every other refueling outage. If these examinations identify

IS! Program Plan

Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 2 (Page 7 of 10) unacceptable results that require flaw removal, flaw reduction to acceptable dimensions or welded repair the requirements of 4.a above shall be applied during the next refueling outage.

5.1.3 J-Groove Weld lSI NDE Requirements Note 4 permits a reinspection frequency of every other cycle when the surface examination results of the EFR are verified to be acceptable for two consecutive cycles after the original installation or repair of the EFR. Westinghouse Report LTR-PSDR-TAM-14-005, Revision 3 (Reference 13; provided in Attachment 3) provides the technical bases for reducing surface examination requirements for J-groove weld repairs. This technical justification includes a detailed review of PT examination history, review of potential causes of PT indications in EFRs, and the use of crack resistant alloys in the EFR. The EFR is a robust design that is resistant to PWSCC. EFR installation, examination, and operational history indicate that the EFR performs acceptably. Examination and removed sample history indicate that the flaws identified shortly after installation of EFR weld material were due to embedded weld discontinuities and not due to service induced degradation. With inspection of the EFR every other cycle of operation, the nozzles are adequately monitored for degradation by ultrasonic examination methods similar to the nozzles without EFR repairs.

EGO projects that the reduction of the PT examination of nozzles would result in a dose savings of approximately 0.4 to 0.7 REM per nozzle examination. The historical radiation dose associated with these examinations is presented in Reference 13, Table

2.

The proposed changes to the inservice examination requirements assure that the EFR repaired nozzles are adequately monitored through a combination of volumetric and surface examinations throughout the life of the installation at a frequency approved by the NRC, thus ensuring the EFR repaired nozzles will continue to perform their required function.

5.1.4 Reporting Requirements and Conditions on Use EGO 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.

IS! Program Plan

Units 1 and 2, Third Interval 10 CFR 5055a RELIEF REQUESTS 13R-09 and 13R-20 Revision 2 (Page 8 of 10) 5.2

Technical Basis for Proposed Alternative As discussed in WCAP-1 5987-F, 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 twenty 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 closure head and penetration tube region since cyclic loading is negligible, as described in WCAP-1 5987-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-1 5987-P.

WCAP-1 6401 -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(z)(1).

ISI Program Plan

Units 1 and 2, Third Interval 10 CFR 50.55a RELIEF REQUESTS 13R-09 and 13R-20 Revision 2 (Page 9 of 10) 6.0

DURATION OF THE PROPOSED ALTERNATIVE The duration of the proposed alternative is for the remainder of the Byron Station Units I 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 OD 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).

8.0 REFERENCES

1. Westinghouse WCAP-1 5987-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-1 6401 -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

IS! Program Plan

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

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 (TAO 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 Welds Section 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 (TAO 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 (EGO), "Byron Station, Unit No. 2 -

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

10. NRC Memorandum, "Byron Station, Unit No. 1 -Verbal Authorization of Relief Request 13R-1 9 - Alternative Requirements for Repair of Reactor Vessel Head Penetrations 64 and 76 (TAO No. ME5877)," dated March 29, 2011

11. NRC Memorandum, "Byron Station Unit No. 1 - Verbal Authorization of Relief Request 13R-1 9 - Alternative Requirements for Repair of Reactor Vessel Head Penetrations Nos. 31 and 43 (TAO No. ME5948)," dated April 13, 2011

12. Letter from Jacob Zimmerman, (U. S. NRC) to M. J. Pacilio, (EGO), "Braidwood Station, Units 1 and 2 and Byron Station, Unit Nos. 1 and 2 - Relief Requests 13R09 and 13R-20 Regarding Alternative Requirements for Repair of Reactor Vessel Head Penetrations (TAO Nos. ME6071, ME6073, and ME6074)," dated March 29, 2012, ADAMS Accession No. MLI 20790647

13. Westinghouse Report LTR-PSDR-TAM-14-005, Revision 3, "Technical Basis for Optimization or Elimination of Liquid Penetrant Exams for the Embedded Flaw Repair," dated May 2015

14. Letter from J. Zimmerman (U.S. NRC) to M. Pacilio (EGO), "Byron Station, Unit No.

1 - Inservice Inspection Relief Request 13R-19: Alternative Requirements for the Repair of Reactor Vessel Head Penetrations (TAO Nos. ME5877 and ME5948),"

dated February 1, 2012