05000219/LER-2012-003, Regarding Indications Identified in the Control Rod Drive Return Nozzle (N9)
| ML13025A082 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 01/07/2013 |
| From: | Peak R Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RA-13-004 LER 12-003-00 | |
| Download: ML13025A082 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| 2192012003R00 - NRC Website | |
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ControlRod Ouvk* Retur Nozzle (W). TMe kidlofsla woorew* ntfied be on fto oubide mufec of fti #pipi.
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mnW"de dmeteW connected Correcdv sfacilok"nlu repai to ft is lo aftio s a A fil litmbo* wel ovefla (WOL) TVe WOPM wI lrwtIsd using vemslsmt stainles fte WOL i ith a dells Ofteti Ile o
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CONMINUA1W SHEET Oyster Creew, Unit 1 S001 2
OF 3
2012
- 003 00 PtaM Coanikr Pta To Event Event Dts: November 7, 2012, Event Time: 12:40 EST Unit1 Mod. Cold Shutdown, Power Lel: 0%
Oees1rpoll of Ewne On November 07, 2012 at 1240 EST while Vi reactor'was In the Cold Shutdown Conton for Re n Outage IR24, two 'k atn were ieie In Ste Control Rod Drive Rturm Nozzle (NO). The indications were Identified to beaon the outside surfac of fthepipng during dye penetraitteVi.
The indications were in themalaent base materia are of the System Pmsur Boundary weld. The Mdicao wre located Top Dead Cent of the 3 inch pipe. In*ation #1WO wap n 0.7 Ir0hesaayM flrom theWeltoeO W &h Was S long. Indication
- 2 was down cstra 02 Inches way frq tie weld toe and the nctinwas 2.50 long. The idiction were discovere as partiof In-Srvice, Isecton being perormed In accordance with station procedure and ASME Section X1, inspeCion CaeorY a-J, Item Number 0021.
Corretive actiOn ýincluded 0 t.i ftoVl location using a 14l stuctusul weld overay (W&L). The WOL WAS instlle using resistant stainless We WOL nmatri with a delta bft level above 7.5 FN (Ferie Number). The WOL extended fom Vie seaedonto th pipe*
an pba ebow to ensueuall Iniain found as pet of exen of tonditon Inosecftin war oere d oO by ie 'ft stuctura weld overa.
The repair was coqplsted on November25 2012 and a pcotrepalr pressure tes followed, which validated fth otepty0OVropa and the,,V Class I pressure boundary.
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- - of ILvent sipl.TcancWe since e Ido*iation wereo e found during -seric Inspecti and the condition ldn~was 6ur(cSCOIncatlo only anid notm innrdamewe connected. These Indications did not yield a through-wa ?"
fl i nd did" otreult In any Rek~0i fteRactor Cacoln System bonday Aditiona exI nain were performedin accordence wit ANIE Secio XI requirements with no unacce9-ptable Idiaon found.
The most probble caus of fth sufac indictonsm was detrmned lo be ouftsd diamete stress, corrosion craclriig. The mateia where Vie Indications were found Is wauste stainless steO which Is suscep"il to 0*l t"e of CMacn The invesgaon paer neokId a Mre of fini the inda W reveald t there was no molsre or laiage boind in fi area of te Indications. Ultanc examinsion also confrme ie Indkicti wer not inside diameter connected.
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CONTIIUATION SHEET
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Nli The design of the OCNGS sae end pIP, and eibow wel ovelday was peformed In ac atce ith r ireme of ASE Code Cse tNs04-4 (2] and ASME Code, Section Xl, NonmndAry Appendix
[$3. The weld overlay is demonsted to be acceptable for one operati cycle of 24 months based on the f*, owin.
- 1. In accordance with ASME Code Case N-504-4, structural design of the overlay was peftmed t0 m the requirements of ASME Code, Section Xl, WB-3640 based on an assumed ctrcumferenial flaw 100% through-wall, and 360 around the original wel The rmsug full struural weld overlay thus restores the original safety margins of the original weld, with no credit taln for the underlyi flawed maea.
- 2. A qualitatve assessment was perlormed by asstming a oonservaive thermal traent and using other weld overlaid nozze results with *ilar dimensions and transients to demonstis that over one pat cycle of 24 months, ASME Code, Section 11I fatigue and fatige crack growth arteria will be satsf.ed 3, After completion of the WOL application, mesfuements of the weld ovefty showed that all WOL dimensions exceeded the design minimum
- 4. A waik down of the effected line following the WOI application indicated that SM hangers and other Kpports were e*ther within or reset to design dimensional toeances.
Bsed on the above observations and the fat that similar weld ovea" hve be applied to other pWfnt since 1066 wvth no subsequent problems Identiied, 4t Is concluded that he NO nozole weld ovea can safely Operate for one operating eyce of 24 month. Su& squant analysis is being peome to upport safe operalio for continued operatin cycls.
PcmvkmOesumses There have been no simila Ucenmee Event eports assocate* wit this component failure rsbm at OCGS In the last three years.
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