ML20094F344

Requests Approval for Use of Helical Coil Threaded Inserts, Per ASME Code Case N-496.Potential Need for Helical Coil Threaded Inserts Identified During Contingency Planning Efforts for Upcoming Outage to Repair RCS Leakage

ML20094F344
Person / Time
Site:	Waterford
Issue date:	02/14/1992
From:	Burski R ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20094F350	List: ML20094F344 ML20094F352
References
W3F1-92-0120, W3F1-92-120, NUDOCS 9202210258
Download: ML20094F344 (4)

Text

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n r.rutaki W3 F 1 0120 M . 05 QA February 14, 1992 U.S. Nuclear llegulatory Commission ATTN: Document Control Do k Washington, D.C. 20565 Subject : Waterford S SI:S Docket No. 50 3h2 License No. Npi'-3h Use of llelical Coll Threaded inserts for Steam Generator Itepair Gentlemen:

Entergy Operations, Inc. requests approval for the use of helical coil (helicoll) threaded inserts, as defined by the ASME Iloiler and pressure Yessel Code Case N 196, "lielical Coll Threaded Inserts," ( Attaclunent 1) in any steam generator manway cover stud holes that are found with darnaged threads at Waterford 3 SI:S. In addition, it is requested that the scope of the exemption be expatuled to envelopo three helical coils that were installed on the steam generator prhaary side manway covers during Waterford 3's fourth refueling outage. This request j is based on the allowance of proposed alternatives to the NitC accepted portions l of the ASME code as speelfled in 10 CFit 50.55a(a)(3) and USNitC llegulatory l Guide 1.117, Revision 8. Finally, Entergy Operations requests that the review of this exemption be expedited such that Waterford 3 may begin utilizing this repair techuhl ue- if necessary- during the outage scheduled to begin on February 17, 1992.

The potential need for helical coil threaded inserts was identified during contingency planning efforts to support Waterford 3's upcoming outage to repair Reactor Coolant System (ItCS) leakage past the number one steam generator cold leg manway. Given llCS leakage past the manway cover, boric achi corrosion may make stud removal difficult . If alternative means (drilling, for example) are necessary to remove the studs, the potential exists that the threaded manway cover stud holes will be damaged in the process.

!!ecause helical coil threaded inserts can restore a stud hole to its original diameter and load carrying capnelty, they represent a superior alternative to more conventional stud hole repair techniques; their use minimizes radiological exposure to maintenance workers as well as impact on the outage schedule. For extunple, the proposed method avohls the need for oversized studs- necessary if a 9202210258 920214 PDR ADOCK 05000382 P

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W3F1-92-0120 Use of llelical Coll Threaded Inserts for Stearn Geiwrator Itepair page 2 l February 14, 1992 j

T stud is drilled out and the threads are retapped- and tints shaplifies future taalutettunee and prevents logistles coinplications. The superiority of a helleoll  ;

repair to the second alternative provided for in ASME Section XI- redrilling tlw

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hole alter weld build-up- is even more pronounced, it is clear that welding on a pressuro vessel in a field environment under severe radiologletd conditions would i present extremo difficulties.

Combustion Engineering enleulation CENC-lh05, "Waterforr'. Unit No. 3 Steam Generator Manways," dated March 15, 1988, confirms ilun helicoli threaded ituwrts may be installed in any or all of the closure stud holes in the steam -l generator primary or secondary side taanway covers. The calculation is inclutted  !

as Attnelunetit 2.

The need for prior approval from NltC for tlw use of twlleolls was recognized by Waterford 3 personnel while preparing for the upcondng outage. Subse<pient review confirmed that helicoils had been used to repair primary manway closures during tho fourth refueling outage and that NitC had not approved their use.

Currently hellcal call threaded inserts are installed in the threaded closure holes l nssociated witti stud to on #1 Steam Generator hot leg prhaary manway and studs t

'18 and 19 on the #2 Steam Generntor cold leg primary manway. The inserts were installed to repair _ dmnaged threads under Non-Conformance Itepair packages 274121 and 274033, respectively.

Although a safety evaluation was conducted in accordance with 10 CFit 50.59, the  !

provisions of to CFit 50.55a(a)(3) were not observed in that N1(C approval was not obtained before the repu'rs were mado. Waterford 3 Quality Notice (QN) 92- ,

008 has been written to document the problem, determine the root cause, and identify necessary corrective actions. l Nevertheless, a review of the documentation assoelated with the steam generator

! repairs confirms that the three helicoils lustalled during the fourth refueling outage satisfy each of the criterin listed in ASME Codo Case N-100.  !

In a unmary then, because the helical coil threaded inserts satisfy the criteria of 10 CFit 50.55a(a)(3), Entergy Operations, Inc. re(pmsts approval to use helleal ,

coil turended inserts as necessary to support iminway cover threaded hole repair.

The proposed uso of helleal coil threaded inserts shall bo in accordance with the condit'ons specified in ASME Inoller and Pressure Vessel Code Case N-400.

-Finally , Entergy Operations re<pients timt this approval be extended to bound the helleoll threaded inserts installed during the fourth refueling outago in order to support plant startup following the outage.

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'W 31'l-9 2-0120 Use of IIelleal Coll Tliremlett liiserts f or Steam Generator itelutir l' age 3 rebruary 14, 1992 Slioulti you luive atiy tjuestions regulating tiils inatter, gilense contact T.W. Gates tit (501) 739-6097.

Ve y truly yours,

(,Nf:f jb t t,,

itI'll/TWG / ssf Attaciunents: 1) Code Ca*4e N- 196

2) Conibustion Eligitieering Calculation CI:NC-lh05

3) Waterford 3 Steam Generator 1)esigti 1)ata ce: 11.1) . Martini, NitC llegioni lY 1).1,. Wigginton, NitC-Nitit N.S. lleynolds 11.11. McGeheo NitC ltesidelit ins >ectors Offlee

Attccheerit 1 to W3F1-92 0120 CASE N 496  !

CALLS OF AIME poltiR AND PREJll'At Ytalf L CODL Approvel pete: Metsh te, test See Namentelindes for esparetoon ons enr inWmetron enten.

Conn 4M connection. l'or materials not listed in the Comtruc.

E Hellcal. Coll Thr:6ded Innrts tion Code, primary stresse6 shall not escetd % of the Settlen Al, Dielslen I minimum specified yield strength or % of the mini.

mum specified tensile sitength of the applicable me.

Inguky: What rules apply to the use of helical coil terial, whichevet is lower, i threaded inserts in pressure retaining items under (c) The helical coli threaded insert shall be pur.

Section XI, Division 17 thesed in accordance with the Ownet's Quality As. l surance Psogtom. Tbc supplier shall be evolusted for l Aeply: It is the opinion of the Committee that hel, cornpliance with NCA 3300 or 10CFR50, Appendte l B-ical. coil threaded inserts may be used in pressure totalning items provided the following requirements (d) llelical enil threaded inserts 6 hall be supplied with a Certified Material Test Report that prwides are met:

fa) The installslion of the helical coil threaded in, traceability to the item, material specintetion, grade  ;

sert shall be performed in socordance with IWA.7000 or cless, mechanical properties, and heet tre sted eon. ,

and IW8 7000, IWC.7000, or IWD 7000, as appil. dition.  !

(e) lielical coil threaded inserts shall be installed E l cable.

- (6) The helical coil threaded insett shall satisfy the in accordance with the manufacturer's instructions.

design requirements of the Construction Code for (f) Use of this Case shall be docuniented in the the specified loadings to be applied to the threaded appropriate Owner's Report. l' i

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