ML062010210

Response to NRC Request for Additional Information and Revised Pilgrim Relief Request, PRR-15, Rev.1

ML062010210
Person / Time
Site:	Pilgrim
Issue date:	07/14/2006
From:	Bethay S Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MC8295
Download: ML062010210 (34)

Text

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';;Entergy Entergy Nuclear Operations, Inc.

Pilgrim Station 600 Rocky Hill Road Plymouth, MA 02360 July 14, 2006 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 Stephen J. Bethay Director, Nuclear Assessment

SUBJECT:

Entergy Nuclear Operations, Inc.

Pilgrim Nuclear Power Station Docket No. 50-293 License No. DPR-35

REFERENCE:

Response to NRC Request for Additional Information and Revised Pilgrim Relief Request, PRR-15, Rev.1 (TAC NO. MC8295)

1.

NRC Request for Additional Information, dated May 11, 2006

2.

Entergy Letter No. 2.05.045, Pilgrim Fourth Ten-Year Inservice Inspection Plan and the Associated Relief Requests for NRC Approval, dated June 29, 2005 LETTER NUMBER:

2.06.047

Dear Sir or Madam:

The Attachments to this letter provide information supporting the re-approval of the Contingency Repair Plan for RPV safe-end-welds, the response to the NRC Request for Additional Information (Reference 1) in support of Pilgrim Relief Request, PRR-15, (Reference 2) and PRR-15, Revision 1, which incorporates changes resulting from Entergy responses to the NRC RAI.

There are no commitments contained in this letter.

If you have any questions or require additional information, please contact Mr. Bryan Ford, Licensing Manager, at (508) 830-8403.

Sincerely, Stephen J. Bethay WGL/dm : : :

Information to Support NRC Re-Approval of 10 CFR 50.55a(a)(3)(i)

In-service Inspection Pilgrim Relief Request (4 pages)

Pilgrim Response to NRC Request for Additional Information (15 pages)

Pilgrim Relief Request, (PRR)-15, Revision 1 (9 pages)

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Entergy Nuclear Operations, Inc.

Letter Number: 2.06.047 Pilgrim Nuclear Power Station Page 2 cc:

Mr. James Shea, Project Manager Office of Nuclear Reactor Regulation Mail Stop: 0-8B-1 U.S. Nuclear Regulatory Commission 1 White Flint North 11555 Rockville Pike Rockville, MD 20852 U.S. Nuclear Regulatory Commission Region 1 475 Allendale Road King of Prussia, PA 19406 Senior Resident Inspector Pilgrim Nuclear Power Station Information to Support NRC Re-Approval of 10 CFR 50.55a(a)(3)(i)

In-service inspection Relief Request (4 pages)

Information to Support NRC Re-Approval of 10 CFR 50.55a(a)(3)(i)

In-service inspection Relief Request Fourth ISI Interval PRR-15, Rev. 1 for Use During the Cumulative Duration of 120 months of NRC Approved PRR-39, Rev. 2

1. Previous 10 CFR 50.55a(a)(3)(i) Relief Request Approved by NRC The NRC approved PRR-39, Rev. 2 (hereafter PRR-39) Contingency Repair Plan for use in the Third 10-Ten Year ISI interval, for use during succeeding 120 months from April 12, 2005 until the expiration of Pilgrim Operating License in 2012. The welds included in PRR-39 are identified in the Table 1 below and were selected for examination during Refueling Outage 15, which was the last refueling outage in the Third 10-year interval.

RFO-1 5 took place in April/May 2005.

Table I: Welds Included in PRR-39, Rev. 2 Contingency Repair Plan.

Weld ID Description System ISI Drawing 14-A-1 SAFE END TO NOZZLE CS IS1-1-14-1 14-B-1 SAFE END TO NOZZLE CS IS1-1-14-1 2R-N1B-1 SAFE END TO NOZZLE RECIRC ISI-I-2R-A 2R-N2D-1 SAFE END TO NOZZLE RECIRC ISI-I-2R-A 2R-N2E-1 SAFE END TO NOZZLE RECIRC lSI-I-2R-A 2R-N2F-1 SAFE END TO NOZZLE RECIRC ISI-I-2R-B 2R-N2G-1 SAFE END TO NOZZLE RECIRC ISI-I-2R-B 2R-N2J-1 SAFE END TO NOZZLE RECIRC ISI-I-2R-B 14-A-3 PIPE TO REDUCER CS ISI-1-14-1 14-B-3 PIPE TO REDUCER CS ISI-1-14-1 14-A-10A VALVE TO PIPE CS ISI-1-14-1 14-B-1OA VALVE TO PIPE CS IS1-1-14-1 The above welds fall within the scope of GL 88-01 and BWRVIP-75A. The A version of BWRVIP-75 was approved by the NRC in a SER dated May 14, 2002.

PRR-39 (Table 1 above) included only those welds which were scheduled for inspection during RFO-1 5, but excluded all other RPV safe-end to nozzle welds, because the Table 2 welds had already been inspected during the previous refueling outages within the Third 10-year ISI interval. The Contingency Repair Plan was to preclude exigent reviews if a flaw was identified. Entergy opted for NRC approval of a Contingency Repair Plan before the start of the RFO-15 for the Table 1 welds that were scheduled for inspection during that outage.

By this application, Entergy requests NRC to include the remaining RPV safe-end welds identified in Table 2 in the Contingency Repair Plan for use within the 120-month duration that was approved by Reference 1 on April 12, 2005. These RPV safe-end welds fall within the material conditions, repair plan, and examination techniques already reviewed and approved by the NRC for PRR-39 with no material changes. These welds fall within the scope of GL 88-01 and BWRVIP-75A.

Page 1 of 4

TABLE 2: RPV Safe-End to Nozzle Welds Included in PRR-15, Rev. 1 Weld ID Description System IS.I._

Drawing 2R-N2A-1 SAFE END TO NOZZLE RPV ISI-1-2R-A 2R-N2B-1 SAFE END TO NOZZLE RPV ISI-I-2R-A 2R-N2C-1 SAFE END TO NOZZLE RPV ISI-1-2R-A 2R-N2H-1 SAFE END TO NOZZLE RPV ISI-1-2R-B 2R-N2K-1 SAFE END TO NOZZLE RPV ISI-l-2R-B RPV-N9B-1 SAFE END TO NOZZLE RPV ISI-1-54-4 As stated in Item 5 of the NRC SER Letter, dated April 12, 2005 (Page 12, Reference 1),

NRC approved the Contingency Repair Plan for the remaining service life of Pilgrim Station, 8 years from 2005 to 2012, since the current Operating License would expire on June 8, 2012, and the cumulative duration for the Contingency Repair Plan would remain in effect for less than 120 months. Entergy plans to inspect all of the welds contained in Tables 1 and 2 within this 120-month period. If flaws are identified, they will be corrected in accordance with the approved alternative Contingency Repair Plan.

Entergy's request for approval of the Table 2 welds (PRR-15, Rev 1. welds) for inclusion within the previously approved alternative Contingency Repair Plan (PRR-39 welds) pursuant to 10 CFR 50.55a(a)(3(i) is based on the following.

NRC has approved up to 120 months for the applicability of approved 10 CFR 50.55a(a)(3)(i) relief request PRR-39 in transition from the Third to the Fourth ISI interval, limited by the expiration of Pilgrim's current Operating License in 2012.

Such authorization is within the scope of the 10 CFR 50.12(a)(1), Specific Exemptions, whereby, the approval as authorized by law will not present an undue risk to the public health and safety, and is consistent with the common defense and security. NRC SER on PRR-39 is applicable in its entirety to PRR-115, Rev. 1, because Entergy will be using all the Code Cases previously approved by the NRC in the PRR-39 SER, as explained in item 2 below.

Therefore, inclusion of Table 2 welds in the previously approved Contingency Repair Plan should be granted, because the Contingency Repair Plan remains valid and in effect.

2. Changes to the Applicable ASME Code Section and Code Cases ASME Section Xl Code Cases for the Contingency Repair Plan overlay design, repair, and testing, and the circumstances and basis of previous NRC approval for PRR-39 have not changed. The Contingency Repair Plan is based upon the requirements of ASME Code Cases N-638, N-504-2, N-416-2, and N-498-4. During the application of PRR-39, Entergy specified these Code Cases as approved in Regulatory Guide (R.G.) 1.147, Rev. 13. At this time, these Codes Cases have been revised and/or conditionally accepted in Table 2 of R.G. 1.147, Rev. 14, as presented below.

ASME Code Cases N-638 (acceptable in R.G. 1.147, Rev. 13) and N-638-1 (conditionally acceptable in R. G. 1.147, Rev. 14).

" ASME Code Cases N-504-2 (acceptable in R.G. 1.147, Rev. 13) and N-504-2 (conditionally acceptable in R. G. 1.147, Rev. 14).

" ASME Code Case N-416-2 (acceptable in R.G.1.147, Rev. 13) and N-416-3 (conditionally acceptable in R.G.1.147, Rev. 14).

Page 2 of 4

ASME Code Case N-498-4 conditionally acceptable in both Rev. 13 and 14 of R.G.

1.147.

Entergy evaluated the changes in the above Code Cases that were approved in Table 1 and 2 of R.G.1.147, Rev. 13 or 14, as applicable, and confirmed that the requirements of these Code Cases did not change the design, fabrication, and testing of the overlay repair plan. Thus, Entergy has concluded that the previously NRC approved Code Cases for PRR-39 are applicable for PRR-1 5, Rev. 1, without exceptions.

Furthermore, R.G. 1.147, Rev. 13 and Rev. 14, in paragraphs 2 on page 3 both state that:

"If a Code Case is implemented by a licensee and a later version of the Code Case is approved by the NRC and listed in Tables 1 and 2 during licensee's present 120-month ISI program interval, that licensee may use either the later version or the previous version."

Since Entergy is requesting approval of relief request within the previously approved cumulative 120-month duration granted for PRR-39, Entergy opts to continue to use the previously approved Code Cases for PRR-15, Rev. 1.

There is added benefit in maintaining uniform design packages for the Contingency Repair Plan throughout the duration until the expiration of current Pilgrim Operating License. Accordingly, Entergy has concluded that NRC SER on PRR-39 is applicable in its entirety to PRR-1 5, Rev. 1.

3. Component Aqinq Factors The welds included in the ISI Relief Request PRR-39 and PRR-15, Rev. 1 are subject to the aging effect of reactor operation. However, degradation of welds due to aging is no longer a factor since the implementation of hydrogen water chemistry to arrest IGSCC at Pilgrim, as discussed in Reference 3. Therefore, aging has no material impact on the purposed alternative Contingency Repair Plan within the scope of 10 CFR 50.55a(a)(3)(i).

4. Changes in Technology and Inspection and Testing of the Affected ASME Code Components As stated in Reference 1, (also discussed in Reference 3) the NRC has approved the latest technology (PDI methodology for UT examination and system leakage test in lieu of radiography) for inspecting and testing the weld repairs to satisfy the ASME Code Case N-416-2 and N-504-2 as the Construction Code for the overlay design, fabrication, and testing.

5. Confirmation to Renewed Applicability of Previously Approved Contingency Repair Plan Pursuant to 10 CFR 50. 55a(a)(3)(i)

Entergy requests the approval of Pilgrim Relief Request PRR-1 5, Rev.1 in order to use the previously approved Contingency Repair Plan pursuant to 10 CFR 50.55a(a)(3)(i) since it was previously approved by the NRC as an alternative repair plan for ASME components (welds) in accordance with NRC approved applicable ASME Code Cases. All of the information Entergy docketed in support of the PRR-39 is applicable to PRR-15, Rev. 1 and all of the information included in the NRC Safety Evaluation approving the PRR-39 is applicable for PRR-15, Rev. 1. Therefore, Entergy concludes that the Contingency Repair Plan presents an acceptable level of quality and safety to satisfy the requirements of 10 CFR 50.55a(a)(3)(i). Similar proposed alternatives were approved by the NRC for James A Fitzpatrick (TAC No. MB0252, dated October 26, 2000), Duane Arnold Energy Center (NRC Staff's letter dated November 19, 1999), Nine Mile Point Unit 2 plant (NRC Staff's Page 3 of 4

letter dated March 30, 2000) and for Pilgrim to repair the RPV N10 nozzle to safe-end weld (Third Interval PRR-36 and 38).

6. Duration of Re-Approved 10 CFR 50.55a(a)(3)(i) Contingency Repair Plan The Contingency Repair Plan for welds included in the Fourth Interval PRR-1 5, Rev. 1 and Third Interval PRR-39 would remain in effect till the expiration of current Pilgrim Operating License in 2012, for a cumulative duration not to exceed 120 months from April 12, 2005.

7. References

1. NRC Letter, Pilgrim Relief Request PRR-39, Rev. 2, Alternative Contingency Repair Plan for Reactor Pressure Vessel Nozzle Safe-End and Dissimilar Metal Piping Welds using Code cases N-638 and N-504-2, with Exceptions (TAC NO. MC 2496), dated April 12, 2005.

2. Entergy Letter, 2.05.024, Pilgrim Relief Request PRR-39, Rev. 2, Contingency Repair Plan Reactor Pressure Vessel Nozzle Safe-End and Dissimilar Metal Piping Welds using Code cases N-638 and N-504-2, with Exceptions, dated March 16, 2005.

3. Entergy Letter, 2.04.091, Response to NRC Request for Additional Information and Revised Pilgrim Relief Request PRR-39, Rev. 1 (TAC NO. MC 2496), dated October 12,2004.

Page 4 of 4 Enteray Response to NRC Request for Additional Information (3 pages)

Enclosure [11 to Attachment 2 (12 pages)

ENTERGY RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION NRC QUESTIONS:

QUESTION 1 The Table on page 1 of the relief request states that the maximum diameter of the pipe to be overlaid is 13.38 inches yet on pages 3, 6 and 7 of the relief request, reference is made to a 29 inch O.D. nozzle. Since this overlay is for 13 inch diameter nozzles or smaller, delete all references to any size larger than 13 inches, i.e., 29 inches.

ENTERGY RESPONSE:

The revised Table 1 in the attached PRR-15, Rev. 1 provides corrected information.

References to any size larger than 13 inches OD have been deleted from PRR-1 5, Rev. 1 QUESTION 2 The Table on page 1 should identify the area (in square inches) of the repair that is in contact with the low alloy steel (P-No. 3) material for each overlay.

ENTERGY RESPONSE:

The flaw indication would provide the information (depth and length) to determine the repair area in contact with the low alloy steel material (P-No. 3) area. Prior to the repair/replacement of the discovered or indicated flaw, Pilgrim will prepare the surface area (excavated or grinded) for overlay design of repair/replacement. The finished repaired areas will be less than 300 square inches.

QUESTION 3 In the relief request identify the original Code of Construction and Code of Record for the 4th interval.

ENTERGYRESPONSE This information included in the revised PRR-15, Rev. 1 (Attachment 3)

QUESTION 4 Identify the start and end dates of the relevant inspection interval.

ENTERGY RESPONSE Pilgrim is in the 4th ISI interval, that began on July 1,2005 and ends on June 30, 2015.

QUESTION 5 On page 6 of the relief request the statement is made, "Alloy 52 with its high chromium content provides a high level of resistance to hot cracking." Provide a justification for this statement.

Page 1 of 3

ENTERGY RESPONSE Filler Metal 52 has been shown to be more hot-cracking resistant than Filler Metal 82 in two EWI solidification cracking studies [1].

Improved understanding of the welding processes have lead to a combination of these new consumables and optimum welding procedures that are resistant to hot cracking. Alloy 52 with its high chromium content provides a high level of resistance to hot cracking provided that the welding parameters are managed properly. This is also discussed in BWRVIP-75A as approved by the NRC.

QUESTION 6 The "Basis for the Alterative," as noted on page 6 and continuing on page 7 of the relief request under "Exception from Code Case N-504-2 Paragraph (h)," is inadequate. The relief request should discuss the basis in more detail to justify the performance of an ultrasonic examination in lieu of a radiographic examination of the weld overlay repair.

ENTERGY RESPONSE The details of the performance of Ultrasonic Testing /Performance Demonstration Initiative (UT/PDI) examination and system leakage tests in lieu of radiographic examination have been discussed in Reference 3, as part of the 3rd Interval ISI Relief Request, PRR-39, and is hereby incorporated by Reference.

The overlay welding would be examined to 1998 with 2000 Addenda ASME Code, Section Xl, Supplement 11 as modified by Fourth Interval Relief Request PRR-9 (TAC NO. MC8292, dated March 22, 2006) approved for specific PDI procedural details. The qualified procedures are in accordance with the ultrasonic acceptance standards included in Section III NB-5330.

The ultrasonic procedures and personnel used for this examination result in a weld material assessment for an overlay that cannot be achieved by radiography. This is based on the special nature of the weld overlay, which is similar to that recognized in ASME Code Section III NB-5270 "Special Welds" and the allowance as described in NB-5279 that there are special exceptions requiring ultrasonic rather than radiographic examinations.

Pressure vessel and safe-end welded piping are filled with reactor water, which precludes use of radiography for weld material assessment. Removal of fuel and draining the vessel to accommodate radiography presents additional nuclear safety and personal hazards.

Additionally, radiography is not qualified under PDI for weld overlay inspections. Thus UT/PDI examination is the preferred method for weld overlay assessment. The qualification process for the Supplement 11 ultrasonic examination, the ability to size flaws for length and depth, and the fact that the qualification includes flaws that may be created during fabrication, meets the ultrasonic procedural requirements of the cited ASME III paragraphs.

The final weld examination would be a complete ultrasonic volumetric examination (UT) using PDI procedure PDI-UT-8 in accordance with Relief Request PRR-9. The weld overlay would meet the requirements of the ASME Code Section XI repair plan and PDI-UT-8. There would be no deviations from ASME Code Section III methods as discussed above and acceptance criteria or UT/PDI procedures. ASME Section Xl allows a repair to be performed by either removing a flaw or reducing it to an acceptable size, as documented for instance in Code Case N-504-2. The weld overlay approach does the latter. The allowable flaw size is defined in Table IWB-3641-1 (since Normal/Upset loads govern). The initial flaw is conservatively assumed to be entirely through wall and to extend entirely around the circumference of the repair location (through wall x 360 degrees around). The weld overlay approach applies additional thickness to the flawed location, such that the resulting as-repaired component Page 2 of 3

meets the requirements of IWB-3640. This approach has been extensively used since the mid-1980's in repair of BWR piping. The weld overlay also imparts a compressive residual stress, which has been shown to reduce crack growth.

The weld overlay repairs will be completed as an ASME Code Section Xl repair using Code Case N-504-2 as the construction code for the repair design, fabrication, and examination methods applicable to a structural overlay type of repair. This type of repair is not included in ASME Code Section III. The nondestructive examination (NDE) of weld overlays is not addressed in ASME Code Section III since it is a construction code used for the initial installation of welded joints. Welding performed under an ASME Code Section Xl repair plan is typically examined in accordance with the code of construction, when applicable, and any Section XI baseline (preservice) inservice inspection (ISI) examinations.

For weld overlay repairs, the construction code is Code Case N-504-2 and the required examinations are by the liquid penetrant and ultrasonic methods.

This Code Case is prescriptive about all aspects of the weld overlay repair including the overlay design, its fabrication, and the examinations performed before, during, and after the welding.

The type of weld examinations to be performed on the structural overlay weld would be based on ASME Code Case N-504-2 as the construction code for the overlay weld repair, rather than ASME Code Section III butt weld joint fabrication, such that the required volumetric examination of weld overlay would be by the UT/PDI rather than radiographic method. An initial liquid penetrant (PT) surface examination would be performed on the area to be welded in accordance with N-504-2. This examination will be performed if required after the localized seal welding is completed. A final PT examination in accordance with N-504-2 and ASME Code Section III would be performed after completing all weld overlay layers. An ultrasonic thickness examination will also be performed to demonstrate that the weld overlay met the thickness requirements of the repair plan.

In conclusion, the applicable weld fabrication and examination requirements of Code Cases N-504-2 and N-416-2, ASME Code Section III, and ASME Code Section Xl (with PRR-9) will be met. Accordingly, performance of an UT/PDI in lieu of a radiographic examination of the weld overlay repair provides an acceptable level of quality and safety.

Enclosure [1]: B. B. Hood and W. Lin, "Weldability of INCONEL Filler Materials", Paper presented at 7th International Symposium on Environmental Degradation of Materials in Nuclear Power Systems, Breckenridge, CO, August 6 - 10, 1995 (12 pages).

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Enclosure rl Ito Attachment 2 B. B. Hood and W. Lin, "Weldability of INCONEL Filler Materials", Paper presented at 7th International Symposium on Environmental Degradation of Materials in Nuclear Power Systems, Breckenridge, CO, August 6 - 10,1995 (12 pages) volOOI.PDF

Seventh International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors

...I Proceedings and Symposium Discussions August 7-10,1995 Brbckenridge, Colorado Organized and Produced by NACE International CosponsoMred by:

The American Nuclear Society The Minerals, Metals & Materials Society Editors Geoffrey Airey, Peter Andresen, James Brown, Steve Bruemmer, Robert Cowan, Paul Doherty, Peter Ford, Frank Garner, Friedrich Garzarolli, Gerald Gordon, John Hall, Natraj Iyer, Christer Jansson, Francois de Keroulas, Harry Levin, Glenn Lucas, Allan Mcllree, Bruce Miglin, Peter Millet, William Mills, Raj Pathania, James Perrin, Steve Sawochka, Peter Scott, Edward Simonen, Tetsuo Shoji, Hiroshi Takamatsu, Robert Tap-

. ping, George Theus, Charles Thompson, Gary Was, John Weeks, Toshio Yonezawa, ONACE

• IMISOM:I NTUMEi 3

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Veldabily Tesft of Inoonel Fdler Materials Ben B. Hood VftW Un Nuclear Service Division Edison rld','g Institute Vestinghouse Electric Coporation Colurbus, Cio 43212 Pensacola, Florida 32514 Abtra~ct This paper presents the finrdngs of a research program aimed at quartfying the weld solidification craddng suscepfibi'ty and weld metal liquation crackdng suceptbility of IncorlTM filler materials 5Z 82, 152 and 182 deposited on a varety of materials irtnded for pressrized water reactor applications. A cursoy Investigation on the repair wldalility of Filler Metal 52 using the Gleebleym t me cal simulation technique is also induded. The brittle temperature range (BTR) in the fusion zone and HAZ was determined using the longitudinal-Varestraint test and spot-Varestraint test, respetri y, and used as a weldability index for quantification of susceptblity to weld solidfication craddng and HAZ liquation craddng. Rest from ths study showed that Filler Metals 52 exhibited the best resistance to both weld solidification cracing and weld metal liquation craddng folowed by 82, 152 and 182 for the base metal combinations tested in this study. Repa weldability study suggested that the resistance to weld metal riquation cracldg of 52 all weld metal would not be signilicantly reduced after ten times of weld simulation at peak temperatures of 9000C and 1300(C.

Since their development over 20 years ago, NI-Cr-Fe Filler Metal 82 and VWeding Electrode 182 have been extensively utilized for wading nickel-based alloys and dissirnilar corrbinations of materials inducing pressure vessel steels and stainless steels Nurnerous inddents of stress corrosion cracing (SCC) with NI-Cr-Fe Alloy 600 materials have been doa.reted leading to the seledion of NI-Cr-Fe Alloy 690 as the material of choice for Nudear Steam Generator Tubing. Over the past decade, Filter Metal 52 a Weldring Electrode 152 have been either selected or considered as a prime candidate matIal for joining UNS N0OM (Alloy 690) materials for pressurized water reactors (PVMs) where primy water stess crrosion a ng (PWSCC) and Intrranuiar strss commson rawkng (GSCC) have been encountered. As a result of the reported superior resistance to stress corrosion craddng (sCC) of 52 and 152 cornpared to 82 and 182 (Refs. I and 2), an Irnlementation plan was developed to replace 82 and 182 tiller materials with 52 and 152 filler materals for replacement steam generator (RSG) applications. In order to corrpare the eldability of 52 and 152 filler materials with 82 and 182 prior to th*ir use, a research program was Initiated to quani the weld solidification oraddng susoep*dity of InoonelTm Or materials 52 152, 82 and 182 using twowelding processes, gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW). Various base metals including nidelbaed alloys, stainless steels, Cr-Mo steels, and carbon steels, were selected representate of irtended applications.

69

Expedmenal Procedur Materials Figure I illustrates the flow dart of experimental procedure for this test and evaluation program.

Basically, a groove was prepared in the base nretal or in the dissirilar joint The filler materials were then deposited in the groove to create weld metal sanrea A pevious study (Ref. 3) has showed that this groove design resubted In about 20% dilution from the base metal. After iller metal deposition, the weld surface were machined 1lush and Varestraint tests were perfomed on the deposited weld metal.

Table I lists the base metal and filler material conrbnationsteted in this study. For Task 12, G(eeblew samples were exrcted from a weld pad deposited using Filler Metal 52. The cherical co01positions of the base metal plates and filler materials are listed In Tables 2 VWeldabrM/Evaluation The newy developed konitucinal-Varestralnt and spot-Varestraint test procedures were ermployed In this study to quantify weld solidification cracing suscepbt and weld metal liquation cracldng susceptibility, respeche (Refs 4 and 5). These nw methodologies prMwd the temperature range over which liquation-related craddrng occurs during weld cooling. This craddng terrperature range is referred to as the brittle temiratuie range (BTR). The concept of using the BTR to quantify weld solidification cracking is presented in Figure 2. The progression of tpem

, rioutucture, ductility and strain in the fusion zone during wed coding is schematically Iustrated. As shown, the weld fusion zone experiences a thermal cyde from a peak temperature above the r:qddus (rT) to rom terrperature (Figure 2a). The n-i rosbudure transforms from a liquid phase to liquid + solid and then completely, to a solid phase upon cooling (Figure 2b). In the kluid + solid state, most engineering materials experience a mnicrostructxe consisting of solid grains surrounded by a thin layer of liquid at the grain boundaries. This nicrostructure is susceptble to cracking since its ability to accorrmodate thermally-wadfor mechanicakk-nued strain Is very low. Figure 2c illustrates the ductlity of a material in a weld cooling cycle. As shown, the ductility drops to an exremely low value in the liquid + solid region and recovers rapidly after the material completely solidifies.

During weld cooling, the thermalyinduced strain is accurulated gradually as illustrated in FRgure 2d.

On a nicrosIrutral level, when the aocunated strain e=xeds the local ductility of the material, cracking occus. The terperature range within w the material erdibits negligible ductility is defined as the BTR A larger BTR allows mnoe strain to be accumulated during weld cooling, thereby increasing the susceptibility to craddrng. The actual value of th upper terpernare bound of the BTR Is very cdifficult to determine, but Is generally approxdmated by the liquidus. "ils concept can also be applied to quantify liquation cracndng suscepbbTdy in the HAZ The BTR is material-specific since it does not depend on conditions during wektebllity testing, thus, it Is a true quantification of weldablllty.

The detailed procedure for using longitudinal-Varestraint tst to deterrine the BTR in the fusion zone and using spot-Varesraint test to detemine ft BIR in the HAZ can be found In the paper previously published by the audtr (Refs. 4 and 5). The test conditions used In this study are listed in Tables 3.

The repair weldablity of Filler Metal 52 was studied using the GleebleTm thenro-mrediancal technique.

For the repair conditions, test samples were reheated 10 times using theml cycles described in Table

3. Two peak temeareS of 900WC and 1300(C were selected to cover a wide enough range of the heat-affected zone. The peak trnperature of 1300C represents a location In the HAZ which is about 0.1 m from the fusion boundary of a weld with a heat input of 0.84 kJ/nrym The detailed methodology for using the GleebleT" hot ductility test to quantify the material susceptibility to HAZ riquation craddng can be found in the a paper prevously published by the author (Ref. 6). The condons for hot ductility testing are listed in Table 3.

70

Re1 and i

D--F.AT C77 T n-For the longunalVarestraint test the maxinrum crack dcstnces (MCD) at augmented stran lwvels ranging from 1% to 7% were detemined. Figre 3 shows tycal test resufts. From these results, the saturated strain and the MCD at a saturated strain can be detemn The saturated strain Is the strain level above hidch the MCD leeed off. The IVICD at a saturated strain represents the entire region o which the ratela is susmetible to solidifica*on crackdng. By combining these MCD results and the cooling rate obtained from the weld cooling cycle, the BTR can be approxdmated. Results of the fusion zone BTR are listed in Table 4. A larger BTR represents a greater susceptibility to weld solidification cracking because a greater amount of strain can be accumulated during acual weld fabrication.

Results form this sudy suggested that the craddng resistance of these four filler materials deposited on 690 nickcl-bas alloy and A2B5 carbon steel is similar and better than lYCr-AMo and 690-316L c-nUnaions.

iller Metals 52 and 82 ehibited sinilar resistance to wed solidification cracking followed by 152 and 182. The 316LNW 52edhibid a better resistance than 690/52 For the spot-Varestraint test, the MCIYs at variable cooling times were determined. The cooling time is the time period between arc extinction and spedmen bending. After testing, the HAZ crack susceptible region can be deternined as typically shown in Figure 4. The HAZ crack susceptible region Is the region In the HAZ in which the material Is susceptible to HAZ liquation crackng. Crackdng persistent for a Iong coding time would represent a greater crading susceilbiiity due to a larger BTR In the HAZ.

The magnitude of BTR at any locatios in the HAZ can be determined by cnTrhV the cooling times and cooling rates during spot-Varestraint testing. The BTR In the HAZ acjacent to fusion boundary of all weld metal tested are listed In Table 5. For all the base metals tested, the cracking susceptibility of filler naterials exhibited the same trend, with 52 showing the best cracking resistance followed by 82 and 152. 316LN152 dxibted a better resistance to solidifcation craddng and weld metal liquation cracking than 690W52-Due to the Inability to obtain a uniform spot weld on Electrode 182, the BTR of the 182 conbinations could not be determined using the spot-Varestraint test The on-cooling GeebleTm hot-ductility tests for Task 12 vwre performed from a peak temperature of 1330"C, which is the nil-strengh terperature (NSW) of the Initial conrdition (no thermal sinulation). Test results showed that the repair condition of 130 0C exhiUted slightly higher ductlitty than the initial condition for the same terrwrtre, as shown In F*Iure 5. Their nil-ductility tieraeature (NDT) and ductiity recovery temrqaeture (DR1) are essentially identical. The repair condition of 900"C edibited a slightly lower NDT and DRT than the initial condltion. Acursory metallurgical irnestigation revealed that repair simulaidons resuted In a more rog rieo strxuce as shown In Fgjures 6-8. Both the solidification grain and subgrain boundaries becarne less distinct, and mrgrated grain boundaries became sharpr as the peak te for repair simnaton increased from 900 to 130(C. These results sxjgeste that there were not significant difference in both the on-heating nil-ductility tenleatumre range and B"R between the repair and initial condmtions. This, the difference In the resistance to weld metal liquation cracking Is negligible between initial condition and simulated repair Conditionsn The weld soridification cracking susceptibility and weld rmeal lkualion racddng susceptiblity of InconelTm tiller materials 5Z 8Z 152, and 182 were quantified using the longitudinal-and spot-Varestraint tests, respectiely. Filler Metals 52 embited the best resistance to both weld solidification cracking and weld metal liquation cracking followed by 82 152 and 182 for the base metal cotbinations tested in tiWs study. A cursory repair weldability study suggested that the resistance to weld rveta liquation cracking of 52 all wed metal would not reduce after ten times of weld repair sinulation.

71

Admowd~mnats This research program was partially supported through funding and materials provided by S.D. Kiser and T. Lenke of INCO Alloys Irtmational. UA Snyder and ML Carpenter spported the VWenghouse program and Vagen Un, Eclison VWding Institute was responsible for perfrming the actual test for WVstinghouse.

Refrnces

1.

Childs, W, "EPRI corrosion studies In BAR enviAronrints of nidmI-sed welding alloys,"

Proceedings of EPRIL-AII Nudear VWeding Synposium on Inconel Filler Metal 52, 72 and Vking Electrode 152, Charlotte, North Carolina, Octber 6-7, 1993, Inoo Alloy Intemaional.

2.

Vidal, P, Buitrne, D., Gimond, C., VdlIlant, F, 'orrparlson of MARSC resistance of InconelTu Welding Electrode 152 n Welding Electrode 182 and FM 82," Proceedings of EPRI-IAJI Nuclear VWeding Symposiumn on Incone Filler Metal 52, 72 and Velding Electrode 152, Charlotte, North Carolina, October 6-7, 1993, Inco Alloy Inernational.

3.

Un, W, Hood, BR Vdabxty testing of Inconel Filler Metal 52, 82 and Velding Electrodes 152 and 182," Proceedings of EPRI-IAII Nudear VWelding Symposium on Inconel Filler Metal 52, 72 and VWeldng Electrode 152, Charlotte, North Carolina, Otober 6-7, 1993, Inoo Aloy Inbernational.

4.

Un, W., Nelson, T. W and Uppold, J. C., "VVldablity testing of stainless steels," Proceecngs of the Bghh Annual Mbrth American lV PawTh Caferenc on recent development in thejo/nin of stain/ess steels and Nhi al/yA Odober 19-22, 1992, Cdurtt, Ohio. Efto VWelring Instite.

5.

Urn W, Uppold, J. C. and Baesladc W A III, 1993, "An evaluation of heat-affected zone liquation craddng susceptibility, Part 1 - Development of a method for quantificationm" Vdng Jourrl Vol 7Z No.4, pp. 134-s to 153-s.

6.

Un, W., Uppold, J. C. a"d Baeslack, W A III, "A nmethdoogy for quanlifyng HAZ llquation cracking suseeptbility using the GeebleTm hot-ductility test," R-oceedfgs of Me fifMh Intatic S)

'wn on FPhyca/ S ffmaion, pp.93-100, Ail 22-24, 1992, The Technical Universi of Dellt, The Netherlands.

72

Table 1. Test matrix Task J Base MetaW Filler Maerial :]Task _Base Meta filler rWiaerial 1

690 52, 8Z 152 & 182 7

600 5Z 82, 152 & 182 2

I 4Cr-24Mo 52, 82, 152 & 182 8

690 & 600 52, 82, 152 & 182 3

690 & 316L 5Z 82,152 & 182 9

690 & 316L 52, 82 152 & 182 4

ASTM A285 52, 82, 152 & 182 10 600 & 316L 52, 8Z 152 & 182 5

316LN 52 11 316LN 52 6

690 52, 82, 152 & 182 12 No 52 Tsk 1- -r L

d Va-es r* test vms or d to study vd sokUldm crad*g susoep*TTdy.

TaskS-11:

Spot-Vawesfrt test ws errdoyed to study weld nme 4u2ion awcdng suscepmuty.

Task 12:

G(eeble'r tendul smidaion aWd hst dctxfty test were eToyed to study weld mta lIquo raddng

=sosebfty at tuAe repa",,ng =,ronition.

Table 2. Checal compositmon of base metal plates and filler materials used.

16901316L11 iYECr-6901 6001316L 316WN 1AM IM 2 152 182 ]

182I 11sk 3,01 31 2 Ia TI7A10 19,10 [5,1114 1-12'1-121

-2j11 C

.0 0.0m0 0.08 0.0a 0.07 0.017 0.014 0.18 0.03 0.041 0M04 0M04 M,

0.24 1.62 0.51 0.12 0L32

1.

1.54 046 024 3.M2 2.89 829 Fe 9.50 68IM 3

9.63 10.07 6.77 Base Base Base

&99 928 1.28 961 S

,=,i 0.009 0.006

<0`01 0.001 0i 0.011 0.038

,,=.001 0.006 0.004 0`00M a

027 0.62 0.64 0.27 021 0.53 0.47 0Q038 0.17 0a49 011 0L43 C

M 0.04 0.32 0.18 0.01 0.06 0.39 001 a.01 0.01 0.11 all O

N

.31 10.12 020 56.66 77A3

10.

10,89 0.01 m0.37 5

71.99 68.93 Cr 30,06 1,27 126 29.95 14.60 17.12 16.61 0.01 28M95 28.87 20.80 13.80 A

0M21 0.45 023 0.63 0.13 mi 029 031 0.24 0.5 0.07 0.40 0.22 0.82 0.01 Co 0405 0.16 mo0.036 06 0.19

<01 0m01 0.05 Mo 2.16 0.48 0.82 2.11 2.20 0.01

<.01

<101 Nb (1001 001

-).008 0.01 1.80 2.44 1.6 P

0.030 0.011 0.009 0.008 0.89 0.034 0.011 0.005 0.005 0.009 0`012 B

0.004 0.08 0.001 N

0.00

.03 0.07 0.144 73

Table 3. Conditions for weldability testing p-ers 5-M GIeetSTM srrnulhon I 9

Ctrtal 170 rafps 90 wrtp Rae

.t*

11 s

111"isw Wotage 12.5 vdts 12 wdtc Hdd Tim 0L03 se 0.03 sec Travel Speed 6

iftn Pek T im

• -wh 900C Ord 130(C 1330"C Eb mx-W M10i9h 0.109n-.

Cocd Ri*e 55C/sec 55"C=sec Distance Gas Fow Rats

, 25 CFH A', 25 CFH Ja Spac 1r lam 19rmn ALnteId SaIn 1-7%

4%

Aftmohv Ar Ar Reofr Bend 10-sec.

10-*se No. d Cydes 10 pojp &4Ey N

DCE SVx d e 5

Rtasec Wll1dn7k I

30sec I

Table 4 Table 5 BTR at fusion zone representing weld solidification cracldng susceptibility of the weld metal tested BTR in the HAZ adjacent to the fusion boundary representing weld metal liquation cracking susceptibility of the weld metal tested 690152 111 690182 123 690'152 193 690/182 227 1YZOCr-'/o15 139 1=Cr--WAD82 162 l YCr-213 Y4AW152 I1Y/Cr-287 YAW/82 690-3161U52 130 690-316L/82 179 690-316ZJ152 274 690-316L/182 300.

MU5M52 112 A20M 121 A28SM52 208 A285M182 269 316LN152 87 Vdd Me BTR ('C) 690__2 79 690M82 173 690/152 243 60052 56 600/82 64 6001152 173 690-60052 91 690600/82 147 69060152 222 690-3161J52 97 690-316=18 179 690-316L/152 220 600-3161.32 96 600-316L/82 147 600-316U152 196 316LN52 54 74

J 1 Base Metal Plate Groove Preparation Filler Metal Deposition Base Metal Plates Joint Preparation E

ji]

Crack Tabulation Varestraint Sample Preparation Varestran Testing Temperature Measurement Figure 1. Row chart of experimental procedure used in this study S

.-4-- Temperature (A) Temperature

• • 1I f

CO I

1 1 (B)

Microstructure I I (C) Ductilituy I

I (D) Strain I

Temperature Figure 2. Theoretical basis for using BTR as a weldability index 75

E E

4 Augmented Strain (%)

8 Figure 3.

Typical longidudinal-Varestraint test results, MCD for the four filler materials with 690 base metal 1.0

~0.8

~OA 0

0 0.5 1

1.5 2

Cooling Time (sec)

Figure 4.

Typical spot-Varestraint test results, HAZ crack susceptible region of the three filler materials with 690 base metal 76

100 80 E60

.40 cc 20 0-1100 1200 1300 Temperature (OC) 1400 (A) On-Heating Hot-Ductility Curve cc 0

1100 1200 1300 Temperature ('C) 1400 (B) On-Cooing Hot-Ducility Curves Hot-dudcirty test results of the Initial and repair condiUons of InconelTm 52 filler, (A) on-heating hot-ductiity curves; (B) on-cooling hot-ductility curves.

Figure 5.

77

Figure 6.

Makrshxuture of the rinitial 52 wii~d mfeWa2=0 Figure 7 MiaDrubure of the 52 weld meta after ten times repair simulations at a peak tererahmtt of 900P C. 200X Rgure 8 Mai* shrbt of the 52 weld metaW after ten times repair simulations at a peak temeattre of 1300C C. 200X 78

DISCUSSION Presenting Author. Ben Hood Questioner Allan McIlrme, Electric Power Research Institute Question/Comment: Would there be any benefit to adding a filler metal to a welded steam generator sleeve application which is now being made by an autogenous weld of alloy 690 sleeve?

Reply: Presently, autogenous welding of alloy 690 sleeving material has been successful. However, some benefit could be derived. The problem becomes a physical one for introducing a filler material.

Questioner-D.C. Agarwal, VDM Technologies Question/Comment: What in the chemistry of filler metal 52 makes it so much better than 82,152 and 182 as far as weld solidification cracking susceptibility?

Reply: It is not fully understood what the major reason is, however the Nb, Ti and Al levels arwe adjusted in the alloy 52, with more Al present in the 52. Typically the GTAW process with wire filler metal using 52 or 82 will be more crack resistant than the SMAW equivalent 152 and 182 alloy.

79 Revised PRR-15, Rev. 1 (9 pages)

PILGRIM RELIEF REQUEST No. PRR-15. Rev. 1 A. COMPONENT IDENTIFICATION A full structural weld overlay repair is proposed for the weldment associated with the six (6) austenitic reactor pressure vessel (RPV) nozzle safe-end and dissimilar metal (DM) piping welds identified in Table 1. This is proposed for contingency repair planning purposes only and will be used, if needed, during a refueling outage within the 4h ISI Interval up to the expiration of current Operating License in 2012. The 4 th ISI Interval commenced July 1, 2005 and ends June 30, 2015.

TABLE 1 SIZE/IWALL ISI WELD ID DESCRIPTION SYSTEM MATERIAL TICE DRAWING THICKNESS DRAWING A-508 Cl. 2 Nozzle Forging, SAFE END TO Inconel 182 Butter, SA-182 F316 13.38" dia. /I NOZZLE (Nuclear Grade C.020%max) 1.31" Safe End Forging A-508 Cl. 2 Nozzle Forging, SAFE END TO Inconel 182 Butter, SA-182 F316 13.38" dia. /I 2R-N2B-1 PVISI-I-2R-A NOZZLE (Nuclear Grade C.020%max) 1.31" Safe End Forging A-508 CI. 2 Nozzle Forging, SAFE END TO Inconel 182 Butter, SA-182 F316 13.38" dia. /

NOZZLE (Nuclear Grade C.020%max) 1.31" Safe End Forging A-508 CI. 2 Nozzle Forging, SAFE END TO Inconel 182 Butter, SA-182 F316 13.38" dia. /I NOZZLE (Nuclear Grade C.020%max) 1.31" Safe End Forging A-508 Cl. 2 Nozzle Forging, SAFE END TO Inconel 182 Butter, SA-182 F316 13.38" dia. /I NOZZLE (Nuclear Grade C.020%max) 1.31" Safe End Forging RPV-N9B-1 SAFE END TO RPV A-508 CI. 2 Nozzle Forging 5 0" NPS IS1-1-54-4 SA-182 F304 Safe End Forging 0.625" These are ISI Class 1 75-A.

welds which fall within the scope of GL 88-01 and BWRVIP-These are proposed contingency repairs.

The actual repaired area (in square inches) and actual repaired configuration in each case will depend on the specific conditions found at the time of the inspections. The finished repaired areas may range in size up to a maximum of 300 square inches at each location dependant on the actual crack location and may be anywhere along the axis of the nozzle. A 300 square inch limit was previously approved for Pilgirm via NRC SER dated April 12, 2005, page 16 (Reference 3).

Page 1 of 9

A. COMPONENT IDENTIFICATION (cont'd)

This relief request is requested under the provisions of 10CFR50.55a(a)(3)(i), in that the proposed alternative would provide an acceptable level of quality and safety.

B. EXAMINATION AND REPAIR REQUIREMENTS The Reactor Pressure Vessel Code of Construction used was the ASME Boiler and Pressure Vessel Code,Section III, 1965 Edition through Winter 1966 Agenda. The ISI and Repair/Replacement Code for the 4 th Interval is the 1998 Edition of ASME Section XI with the 2000 Addenda.

The weld overlays will be designed consistent with the requirements of NUREG-0313, (which was implemented by Generic Letter 88-01), ASME Code Cases N-504-2, N-638, and ASME, Section Xl, Paragraph IWB-3640.

Welder Qualification and Welding Procedures All welders and welding procedures will be qualified in accordance with ASME Section Xl including any special requirements from Section Xl or applicable code cases. If necessary, a manual shielded metal arc weld (SMAW) procedure will be qualified to facilitate localized repairs and to provide a seal weld, prior to depositing the overlay. This procedure will make use of 152 SMAW electrodes consistent with the requirements of ASME Section XI. Only personnel qualified in accordance with the Welding Procedure Specification (WPS) for welding Alloy 52/152 will perform the repair activities.

Welding Wire Material The weld overlay materials (weld wire) for the proposed repairs are as follows:

For automated machine gas tungsten are welding (GTAW), the weld material will be ASME Section II, Part C, SFA-5.14 Filler Metal ERNiCrFe-7A (UNS N06052) ASME IX F-No. 43, known commercially as Alloy 52.

For SMAW welding, the weld material will be ASME Section II, Part C, SFA-5.11 Welding Electrode ENiCrFe-7 (UNS W86152) ASME IX F-No. 43, known commercially as Alloy 152.

Inconel Weld Metal is recognized as an IGSCC resistant material in BWRVIP-75-A Section 5.5.1.1 and 3.5.2.1. This was approved by NRC SER in a letter dated May 14, 2002. The use of Inconel 52/152 was also previously approved for use at Pilgrim via an NRC SER dated April 12, 2005.

Weld Overlay Design The weld overlay will extend around the full circumference of the weldment location in accordance with NUREG-0313, Code Case N-504-2, Generic Letter 88-01, and BWRVIP-75-A. The overlay will be performed using a standard overlay design as described in NUREG-0313, Section 4.4.1. This design assumes a crack completely through the wall for 360. The calculation methods for design of the overlay will be in accordance with NUREG-0313, Section 4.1.

Page 2 of 9

The specific thickness and length will be computed according to the guidance provided in ASME Section Xl, Code Case N-504-2, and ASME Section XI.

The overlay will completely cover any indication location and the existing Inconel 182 weld deposit butter with the highly corrosion resistant Inconel weld material. In order to accomplish this objective, it is necessary to weld on the low alloy steel (LAS) material. A temper bead welding approach will be used for this purpose according to the provisions of ASME Code Case N-638. This Code Case provides for GTAW temper bead weld repairs to P-No. 3 nozzle materials (SA 508 Cl. 2) at ambient temperatures.

The temper bead approach was selected because temper bead welding supplants the requirement for post weld heat treatment (PWHT) of heat-affected zones in welded LAS material.

ASME Code Case N-638, General Requirements 1(a), limits the maximum finished surface area of the weld overlay repair to 100 sq. in. The overlay repair (design and fabrication) on large diameter (13-inch OD) recirculation nozzle safe-end welds would exceed the 100 sq. in. limit and requires NRC approval for a maximum finished weld repair surface area up to 300 sq. in. Analysis contained in EPRI Technical Report 1003616, "Additional Evaluations to Extend Repair Limits for Pressure Vessels and Nozzles", dated March 2004, allows for exceeding this limit and was used by Susquehanna Station as justification for the recent nozzle weld overlay repairs.

If the weld overlay necessary for a nozzle exceeds 300 sq. in.,

additional relief will be requested, as previously approved by NRC SER for use at Pilgirm via NRC SER dated April 12, 2005.

Examination Requirements The repair, pre-service inspection (PSI), and future in-service inspection (ISI) examinations of the weld overlay repair will be performed in accordance with the ISI Program and Plan, BWRVIP-75-A and approved plant procedures as specified by the ISI Repair / Replacement Program.

The weld overlay will be examined using the industry developed PDI procedure, as requested in PNPS 4th ISI Interval PRR-9 (Relief from ASME Code Section XI, Appendix VIII, Supplement 11, Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds).

System leakage testing will be performed as allowed by Code Case N-416-3 in lieu of the system hydrostatic test required by Code Case N-504-2. Code Case N-416-3 is approved in the NRC R.G. 1.147, latest revision.

Page 3 of 9

A description of the required examinations for the weld overlay is provided in Table 2 TABLE 2 Examination Description Method Technique Reference Weld Overlay Surface Area PT Visible Dye N-504-2 Preparation Exam First Two Weld Overlay Layers PT Visible Dye N-504-2 Surface Exam First Two Weld Overlay Layers UT or 00 Long. UT or N-504-2 Thickness Measurements Mechanical Mechanical Height Measurement Completed Overlay UT or 00 Long. UT or N-504-2 Thickness Measurements Mechanical Mechanical Height Measurement Surface Exam of Final Overlay PT Visible Dye NB-5350 Surface and Adjacent Band within IWB-3514 1.5t (7/8" Band) of Weld Overlay.

N-638 This also serves as Preservice N-504-2 Surface Examination of completed overlay.

Volumetric Exam of Final Overlay UT PDI Procedure ASME 1998, and Adjacent Band within 1.5t Section Xl (7/8" Band) of Weld Overlay.

With 2000 This also serves as Preservice

Addenda, Volumetric Examination of Appendix VIII; completed overlay.

as modified by 10 CFR 50.55a Preservice Baseline Exam of UT PDI Procedure N-504-2 Final Overlay Outer 25% of the Underlying Pipe Wall to Identify the Original Flaws.

The acceptance criteria for the volumetric examinations shall be ASME Code Section XI Paragraph IWB-3514, "Standards for Examination Category B-F, Pressure Retaining Dissimilar Metal Welds, and Examination Category B-J, Pressure Retaining Welds in Piping".

It is noted that the curvatures of reactor nozzles require an exception to the ultrasonic inspection requirement for a 1.5t adjacent band volumetric examination at the end of the overlay on the nozzle end. The PT examination of this surface will constitute the acceptance testing for the overlay deposit.

Thickness will be characterized at four (4) azimuths representing each of the four (4) pipe quadrants. Thickness measurements may be determined using UT techniques or by mechanical measurement. Liquid penetrant examinations will be performed at the same stages of the overlay application as the thickness measurements identified above.

Page 4 of 9

The alternative, as described below, provides an acceptable level of quality and safety while neither draining the reactor vessel nor applying preheat and post weld heat treatments.

C. ALTERNATIVE TO REPAIR REQUIREMENTS The repair will utilize ASME Code Case N-504-2, "Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping," and Code Case N-638, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique," with the following exceptions and clarifications.

Clarification of Code Case N-504-2 for Applicability to Nickel-Based Austenitic Alloy Code Case N-504-2 was prepared specifically for austenitic stainless steel material.

An alternate application to use nickel-based austenitic materials (i.e., Alloy 52/152) is requested due to the specific configuration of the nickel-based austenitic weldment.

Exception from Code Case N-504-2 Paragraph (b)

Code Case N-504-2 paragraph (b) requires that the reinforcement weld metal shall be low carbon (0.035 % maximum) austenitic stainless steel. In this application, a nickel-based filler is required and Alloy 52/152 has been selected in place of low carbon austenitic stainless steel.

Exception from Code Case N-504-2 Paragraph (e)

Code Case N-504-2 paragraph (e) requires as-deposited delta ferrite measurements of at least 7.5% for the weld reinforcement. These measurements have no meaning for nickel-based materials and will not be performed for these overlays.

Note for (b) and (e) above:

The composition of nickel-based Alloy weld metals (Inconel) is such that delta ferrite is not formed during welding. Ferrite measurement requirements were developed for welding of 300 series stainless steels. Welds using Inconel are 100% austenitic and contain no delta ferrite due to the high nickel composition (approximately 60% Ni and low iron content). Alloy 52/152 with its high chromium content provides a high level of resistance to IGSCC. Therefore, this alternative provides an acceptable level of quality and safety.

Exception from Code Case N-504-2 Paragraph (h)

Code Case N-504-2 paragraph (h) requires a system hydrostatic test of completed repairs if the repaired flaw penetrated the original pressure boundary or if there is any observed indication of the flaw penetrating the pressure boundary during repairs.

A system leak test of completed repairs will be used in lieu of a hydrostatic test in accordance with ASME Code N416-3 which is approved in NRC R.G. 1.147 latest revision.

Use of Code Case N-638 Applicability Code Case N-638 shall be applied to the nozzle material.

Page 5 of 9

Exception from Code Case N-638 Paragraph 1 (a)

The Code case N-638, General Requirements, 1(a) limits the maximum finished surface area of the weld overlay repair to 100 sq. inches. Relief is requested to extend the size of the repairs up to 300 sq. in. finished area to accommodate overlay repair on large diameter (13-inch OD) recirculation nozzle safe-end welds. This was previously approved by NRC SER for use at Pilgirm via NRC SER dated April 12, 2005.

D. BASIS FOR THE ALTERNATIVE Clarification of Code Case N-504-2 for Applicability to Nickel-Based Austenitic Steel The weldments being addressed are austenitic material having a mechanical behavior similar to austenitic stainless steel. The weldment is designed to be highly resistant to IGSCC and is compatible with the existing weldment and base metal materials. Accordingly, this alternative provides an acceptable level of quality and safety. Therefore, Code Case N-504-2 should be interpreted to apply equally to both materials.

Exception from Code Case N-504-2 Paragraph (b)

A consumable welding wire highly resistant to IGSCC was selected for the overlay material. This material is a nickel-based alloy weld filler material, commonly referred to as Alloy 52, and will be applied using the GTAW process.

Alloy 52 contains approximately 30% chromium, which imparts excellent stress corrosion cracking resistance. Alloy 52 which had been used extensively in the construction of many nuclear plants, is identified as an IGSCC resistant material in BWRVIP-75A. Alloy 52 with its high chromium content provides a high level of resistance to IGSCC consistent with the requirements of the code case.

Therefore, this alternative provides an acceptable level of quality and safety.

Exception from Code Case N-504-2 Paragraph (e)

The composition of nickel-based Alloy 52 is such that delta ferrite is not formed during welding. Ferrite measurement requirements were developed for welding of 300 series stainless steels. Weld using Alloy 52 is 100% austenitic and contains no delta ferrite due to the high nickel composition (approximately 60% Ni and low iron content). Alloy 52 with its high chromium content provides a high level of resistance to hot cracking and IGSCC. Therefore, this alternative provides an acceptable level of quality and safety.

Exception from Code Case N-504-2 Paragraph (h)

In lieu of the hydrostatic pressure test requirements defined in Code Case N-504-2, the required pressure test shall be performed in accordance with Case N-416-3 with the exception that the volumetric examination performed shall be an ultrasonic examination of the weld overlay.

The weld overlay will be examined using the industry developed PDI procedure, as requested in PNPS 4te ISI Interval PRR-9 (Relief from ASME Code Section Xl, Appendix VIII, Supplement 11, and Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds).

Page 6 of 9

Radiography examination would be not be meaningful since the IGSCC flaw is not removed and the piping in filled with water during the weld overlay process. The water backing provides a heat sink which imparts a compressive residual stress which retards future crack growth. This has been noted in EPRI research (EPRI reports NP-7103-D and NP-7085-D). In addition, the water back reduces radiation exposure (ALARA) to the personnel performing the weld overlay.

These alternative requirements are sufficient to demonstrate that the overlay is of adequate quality to ensure the pressure boundary integrity.

Accordingly, this alternative provides an acceptable level of quality and safety.

Use of Code Case N-638 Applicability Code Case N-638 was developed to address temper bead applications for similar and dissimilar metals. It permits the use of machine GTAW process at ambient temperature without the use of preheat or PWHT on Class 1, 2, and 3 components.

Temper bead welding methodology is not new. Numerous applications over the past decade have demonstrated the acceptability of temper bead technology in nuclear environments. Temper bead welding achieves heat affected zone (HAZ) tempering and grain refinement without subsequent PWHT.

Excellent HAZ toughness and ductility are produced. Use of Code Case N-638 has been accepted in Regulatory Guide 1.147 as providing an acceptable level of quality and safety.

The overlay repair on large diameter (13-inch nominal OD) recirculation nozzle safe-end welds would exceed the 100 sq. in. limit specified in Code Case N-638, paragraph 1(a). EPRI Technical Report 1003616, "Additional Evaluations to Extend Repair Limits for Pressure Vessels and Nozzles", dated March 2004, justifies extending the size of the temper bead repair finished area.

The ASME Code Committees have recognized that the 100 sq. in. restriction on the overlay surface area is excessive and a draft code case, RRM-04, is currently being progressed within ASME Section Xl to increase the area limit. Furthermore, Three Mile Island and V. C. Summer have completed weld overlay repairs involving approximately 200 and 300 sq. inches respectively. Susquehanna Station in its Relief Request No.31 has used the EPRI Report, ASME proposed draft code case, V. C. Summer and Three Mile Island expanded repairs as justifications for recent expanded nozzle weld overlay repairs. As discussed in the EPRI Report, increasing the allowed areas for ambient temper bead repairs did not detrimentally change the residual stresses, thereby providing an acceptable level of quality and safety.

Use of Code Case N-638 applicability as discussed above was previously approved by the NRC SER for use at Pilgirm via NRC SER dated April 12, 2005 (Reference 3).

E. CONCLUSION Weld overlays involve the application of weld metal circumferentially over and in the vicinity of the flawed weld to restore ASME Section Xl margins as required by ASME Code Case N-504-2. Weld overlays have been used in the nuclear industry as an acceptable method to repair flawed weld. Use of overlay filler material that provides excellent resistance to IGSCC provides an effective barrier to crack extension.

The design of the overlay uses methods that are standard in the industry for size determination of pipe-to-pipe overlays. There are no new or different approaches used in these overlay designs that would be considered first of a kind or inconsistent Page 7 of 9

with previous approaches. The overlay is designed as a full structural overlay in accordance with the recommendations of NUREG-0313, which was forwarded by Generic Letter 88-01, and Code Case N-504-2 and ASME Section Xl Paragraph IWB-3640.

Temper bead techniques, as defined by Code Case N-638, will produce a tough corrosion resistant overlay deposit that meets or exceeds all code requirements for the weld overlay.

Pilgrim concludes that the contingency repair plan presents an acceptable level of quality and safety to satisfy the requirements of 10CFR50.55a(a)(3)(i).

Similar proposed alternatives to the requirements have been previously approved by the NRC for James A Fitzpatrick (TAC No. MB0252, dated October 26, 2000), Duane Arnold Energy Center (NRC Staff's letter dated November 19,1999), Nine Mile Point Unit 2 plant (NRC Staff's letter dated March 30, 2000) and for Pilgrim to repair the RPV N10 nozzle to safe-end weld (3rd ISI Interval PRR-36 and 38).

Inconel Weld Metal Overlays are recognized as an IGSCC resistant material in BWRVIP 75-A Section 5.5.1.1 and 3.5.2.1. This was approved by NRC SER in a letter dated May 14, 2002 F. DURATION OF THE PROPOSED ALTERNATIVE The proposed alternative applies to the repairs of the identified RPV nozzle safe-end and piping welds for all scheduled refueling outages during the 4 th ISI Interval until the expiration of the current Operating License on June 8, 2012. Re-inspection will in accordance with the BWRVIP-75-A Guidelines. The 4 th ISI Interval commenced on July 1, 2005 and ends on June 30, 2015.

G. PRECEDENTS The six welds specified in this relief request (PRR-15) were not included in the NRC approved PRR-39 from the 3rd ISI Interval (TAC No. MC2496). The weld overlay scope, examinations, and repair requirements for the six welds in PRR-15 are identical to those specified for the welds included in the approved PRR-39.

PRR-39 was approved for the current licensed life of the plant (2012); accordingly, PRR-39 is carried forward to the 4th Interval for all the welds already approved in that relief request until the expiration of the current Operating License on June 8, 2012.

Like PRR-39, PRR-15 is also a contingency repair plan for the specified welds, would remain in effect until the expiration current Operating License.

H. ATTACHMENTS None I. REFERENCES

1. Entergy Letter No. 2.04.091, Response to NRC Request for Additional Information and Revised Pilgrim Relief Request, PRR-39, Rev. 1 (3 rd ISI Interval),

TAC No. MC 2496, dated October 12, 2004.

2. Entergy Letter No. 2.05.024, Pilgrim Relief Request, PRR-39, Rev. 2 (TAC NO.

MC2496) (This revision limits the weld overlay finished area to 300 sq. in. based Page 8 of 9

on EPRI Technical Report 1003616, "Additional Evaluations to Extend Repair Limits for Pressure Vessels and Nozzles", dated March 2004), March 16, 2005.

3. NRC Letter, Pilgrim Relief Request PRR-39, Alternative Contingency Repair Plan for Reactor Pressure Vessel Nozzle Safe-end and Dissimilar Metal Piping Welds Using ASME Code Cases N-638 and N-504-2, with Exceptions (TAC No.

MC2496), dated April 12, 2005.

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