DCL-08-039, Mitigation Status of Alloy 600/82/182 Pressurizer Butt Welds, Structural Weld Overlay Ultrasonic Examination Results

Mitigation Status of Alloy 600/82/182 Pressurizer Butt Welds, Structural Weld Overlay Ultrasonic Examination Results

ML081230617
Person / Time
Site:	Diablo Canyon
Issue date:	04/24/2008
From:	Becker J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-08-039, TAC MD4150, TAC MD4974
Download: ML081230617 (6)

Text

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PacificGas and ElectricCompany' James R. Becker Diablo Canyon Power Plant Site Vice President and Mail Code 104/5/502 Station Director P.0. Box 56 Avila Beach, CA 93424 April 24, 2008 805.545.3462 Internal: 691.3462 Fax: 805.545.4234 PG&E Letter DCL-08-039 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 Mitiqation Status of Alloy 600/82/182 Pressurizer Butt Welds (TAC No. MD4150);

Structural Weld Overlay Ultrasonic Examination Results (TAC No. MD4974)

References:

1. NRC Letter to PG&E, "Confirmatory Action Letter, Diablo Canyon Power Plant, Unit No. 2 (TAC No. MD4150)," dated March 15, 2007.

2. NRC Letter to PG&E, "Diablo Canyon Power Plant, Unit No. 2 - Approval of Relief Request REP-1 U2, Revision 1, For the Application of Weld Overlay on Dissimilar Metal Welds of Pressurizer Nozzles (TAC No. MD4974)," dated February 6, 2008.

Dear Commissioners and Staff:

During the DCPP Unit 2 Fourteenth Refueling Outage, which began on February 4, 2008, Pacific Gas & Electric Company (PG&E) completed preemptive full structural weld overlays (SWOLs) to mitigate the effects of primary water stress corrosion cracking (PWSCC) of susceptible material on the Diablo Canyon Power Plant (DCPP) Unit 2 pressurizer dissimilar metal welds. With this action, PG&E has completed the actions and commitments with respect to PWSCC mitigation addressed in Reference 1.

Reference 2 documents a PG&E commitment to submit a report of the details of the SWOL examination results on the DCPP Unit 2 pressurizer spray, relief, safety, and surge nozzle safe-ends to the NRC within 60 days after completion of the final installation ultrasonic examination. No weld repairs to the weld overlay material and/or base material were required. The examination results were accepted by PG&E on February 25, 2008. The required report is enclosed.

This letter satisfies the reporting requirements of both References 1 and 2.

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon ° Palo Verde e South Texas Project

• Wolf Creek

Document Control Desk PG&E Letter DCL-08-039 April 24, 2008 Page 2 PG&E makes no regulatory commitments (as defined by NEI 99-04) in this letter.

This letter includes no revisions to existing regulatory commitments.

If you have any questions, please contact Mr. Stan Ketelsen at (805) 545-4720.

tcg/4231 Enclosure cc: Diablo Distribution cc/enc: Elmo E. Collins, Regional Administrator, NRC Region IV Michael S. Peck, NRC Senior Resident Inspector Alan B. Wang, Project Manager, Office of Nuclear Reactor Regulation State of California, Pressure Vessel Unit A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Cattaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• South Texas Project e Wolf Creek

Enclosure PG&E Letter DCL-08-039 Weld Overlay Ultrasonic Examination Summary Diablo Canyon Power Plant Unit 2 Fourteenth Refueling Outage (AREVA Nondestructive Examination [NDE] Report Attached)

A April, 1"*8, 2008 Tom: Gro6)zan Diablo Canyon, Power Plant Regulatory services P:.O. BOx 56 vila Beach, CA 93424

Subject:

Weld.OVerlay Uitrasonic Examination Summary, Diablo Canyon Power Plant Unit 2, 2R14 Executive Summary Pacific Gas and Eletric Company (PG&E) performed preemptive full' stqtrural weld oyerlays on six dissimilar metal welds assQciated w"th the6RCs pressurizer at Diablo Canyobn Power Plant (DcPP)

Unit 2 during the Fourteenth Refueling outage (2R14)'in February 2008. These full structural weld overlays (SWLs)-were applied to mitigate the components against potential effects of primary water stress corrosion cracking. AREVA 'NP peformed nondestructive examinations (NDE) of these SWQLs and the outeri 25% of fthe original Weld and base material. The ,following table; summarzes the r*sults of these examnihtions, additional details are d ssequent sections of this letter.

Exam Volum-e.

Coomponent Coverage .... Indications Disposition Repair

• ;~~~(PSI/ISI)

A .Safet Nozzle 1*00%]100% Yes Acceptable. Nt Required

.B Safety Nozzle. 10o0/*Y T00% No .. Not Required N/A, C Safety Nozzle 100%/, 100% No INt Required N/A PzRSp;ySNozzle N ., 1100%,/100%" , No M Not Required' N/A

PZR Relief Nozzle 100%] 100% No NotRequired N/A PZR SUrge.NozzleI 100%. 100% No Not Required N/A Examination Procedures$

The folloWing table lIsts theAREVA NP. procedures used for0examhinations performed at DCPP, 2R14.

Probedure Number P Pro6edure Tile *SDCN .... ::Examination'Methlo;d CQolor Contrast. Solvent

'54-PT-200-07 Removable Liquid Penetrant, 30-9062999-000 Liquid Penetrant Examination of Compnents .

MWet or Dr- Magn'etic Particle Nn a

-Examination Procedure/

Mahiual Ultrasonic Examinhatioh 54-ISI-600,02 of Overlays For Thickness and 30-9062998-000 Ultrasonic

________ profile M ,easurerm nts ._. ______...... ___ ............... _.

Manual Ultr'asonic Examination

54-IS-838-09 Qf Weld Overlaid SimIlar andl 30-9060387-000 UltrasoQnic

_____________Dissimilar Metal Welds

• SafetyV Docume nt charng-e Notice An AREVA end Siemrens 4comPanFy 3315.6 Old rer~t R~oad. 0.O. 6ox 1 0935.ý Lyncbur, VAý24506-0935ý Tel: (34)832300- ax:(434) B32-'384O 40MK i27MAý (,IjZOMý)

Component:" Relief Nz6zil (WiB-380SE)

Weld Number:, WIB-3796380 O.L.

A preemptive structural reinforcement weld overlay of the Diablo Cranyon Unit.2 Pressurizer Relief Nozziei was performed during the 2R14ioutge. This weld ove.lay Was applied over both the nozzle to safe end andpsafe eqnd, to pipe welds.

,Surface examinations of the welddesuitedoverlay in rno indic6tions.

ec.*rdble

'UT examinations of the, applied overlay and adjacent base material were performed using procedures,.personnei! and4equipmentqUalified through the Performance Demonstration lnitiatives implementation of ASME CGdO, section Xlr,.Appendix ViIi, Suppi ment' 11,.

UT volumetric examina.tions resulted ,in:no recordable indications coverage of both the PSI and ISI! examination, volumes was obtained.

00/,0%

Component: SafeMy A Nozzle (WIB*369SE)ý Weld Number: WIB-368-369 O.iL A preemptive structural 'reinforcemenpt Weld'overlay of'the Diablo Canyon Unit 2 Pressurizer Safety A Nozzle was performed during the 2Ri4 outage. This weld overlay was appli ed oVer both thle noze to safe e:nd and safe end to pipe welds.

Surface' examinations of theWeld overlay resulted in no recordable indications.

UT examinations of the applied ovedray and adjacent base material were performed using procedures, personnel panid equipment qualified through the Performance Demonstration Initiative's impiementation ofASME C6ode, Sectih:XlI, AppendixViII, Suppement 1. .

UT vol umetric Nexamrinations r*sulted in two recordable indications .that ýwere eValuated as acceptab!e in accordance with the criteria specified in Diablo Canyon Unit 2, Third Inspection Interval:,;Relief R'40"s REP-I U2. The tw ýindications were c-har-acpterize as "lack of bond" defects, located at the ovyerlay tobase metal interface near the nozzle end' of t1heoVerlay. Thesesmall indications measuring Q0.22 square inches and 0.25 square inc6hes. di notresult.in any eductiion ofthe an'gle bea m ,coverage of the weld -overlay material volume (AB-C-D as depicted in the aforementioned relief request)sirnce the*yare located atthe ýabsolute bottorm of the required: examination volume; nor did they interfere with angle beam eXami nation ofthe PSi/iSi volume dueto their location near the extremity of the overlay.

100%, coVerage;of both the PSI and 181! examination OdmietS wa s obtained.

0omPor.ent. Safety B Nozzle (WIB.423SE)

Weld! Nuimb'er. WiB-422A-423 O,L.

preeemptive strUctural[reinforcement weld overlay of the DiabloCany.on Unit.2 Pressurizer Safety B Nozzle was perfor*ed during the 2R14 outage. This w'ld overlay w6s applied over both 'the nozzle to safe end land safe end to pipe welds.

Surff.aceoexami nations, of the weld'overlayv resulftediin no, recordable inidications.

UT examinations* ofthe, applied overlay an-d adja-ent base, material'wereý performed using ptrocdures, personnel( and' eqipment qUalified, through the Perfo-rmapce. Demon..str~ation I-nitiative's impilementationi of ASME Cod&, Section Xl, Appendix VIII, Supplement 11..

UT vol!uametric examinations resulted ihnAno recordable indica.tions 100'% coverage of both the' PSI and IS1I examination volutmes was obtained.

,ARV NP I NC.

3ý31 5 Ol8 Forest FRoad P.O. Bo 193. yhbyrg. VA 2ýý?450503 Te. _(434 832-3000 - Fex'!:(434)'832-3840 OA 2Ob 4Ic~

Compqonent:, Safety* C Nozzle (WIB-3!59SE)

Weld Nuimber: WIB-358-359 .IL.

fAl preemptive structural; rei nforcement Weld overlay of the Diablo Canyon Unit 2 Pressurizer Safety C N0zze =was performed during the 2R14 outage. This weld overlay was applied over both the nozzle, to safe end and safe end to pipe Welds.

Surface examinations of the weld overlay resulted in no hre*od.able indications.

UT examinations of the appl6ied overlay and adjacent base material were perfo0rmed using procedures, personneliand equiprient' qualified through the Performance, Demonstration Initiative's implpeme ntation of ASME Code,Section XI, Appendix VIII!,, S.upplementt 1.

UT volumetric examinAtiohstressulted "in no re0ordable indicati0ns 1600% coveragem of both the PSI and 15i examinatio.n volumes was obtained.

Co0mponent: Pressurizer Spray Nozzle (WIB-345SE)

Weld NuMber: WIB-345-346 O.L.

A preemptive structural reinforcement Weld overlay of the ýDiablo, Canyon ;Unit i2 Pressurizeir Spray Nozzle was performed during the 2R14 outage, This weld overlay was applied over 'both the nozzle.

to safe end and safe e6nd to pi`pe weld s.

Surface

- aminations of the weld overlay resulted in no recordable inndications.

UT eXaminations of the applied ovetlay and adjacent base matetiaI were performed using procedures, personnel-and equipmentiquialified through the Performahnce-Demonstration Iitiative's implementation o0f ASME Code, Section Xl, Appendix VIII, Supplrement- 11. -

,UT,tvolumetric*examinations resulted in no. recordable indications 100% coverage of both the PSI and ISi examination volumes'wads obtained.

Component: Pressurizer Surge Nozzle (WIB-4395E)

WeldrNumber: WIB-438-439 0,L.

A preeptive structural reinforcement weld overlayof the Diabo Canyoni Unit 2 Piessurize-r Surge NQzzle was p~erformedd~ur~ing the 2R14 outage. This Weld overlay was iapplied over both the nozzle to saffeend and safe end to pie w*elds.

Surfae examinations of the weld overlay resulted ;in no recordable, infdications.

UT examinations ofithe applied overlay and adjacehntbase materiai ..were lperformed using proceodures, personnel and equipment qualified hrough the Perormn 11.Demostration Initiative's implementation of.ASME6Code,Section XI,lSupplement ApPendixVIII, UTvolumetricexaminations resulted in no recordable indicatioln 100% coverage of both the PSI and ISI examination voIumes: was Obtained.

Manager, NDE' Development ,/Technical Operýations AREVA NP 155 Mill Ridge Road

Lynch.buprg, VA .24502

,Office 434-82*-2555 AR.,AN÷"C.

An AktEVAadiemen z opn

~$15OldForet R~d,~.O.box, 19315. Lnhu A25603