ML20115A611
| ML20115A611 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/05/1992 |
| From: | Beck G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9210150001 | |
| Download: ML20115A611 (5) | |
Text
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PIIILADELPlllA ELECTetIC COMPANY NUCLEAR GROUP llEADQUARTERS 955-65 CHESTERBROOK BLVD.
WAYNE, PA 19087-5691 015) Mo*xo sect !!AR $1.RVICI,5 DI PAR 1MINr October 5, 1993 Docket Nos. 50-352 50-353 License Nos. NPF-39 NPF-85 U.
S.
Nuclear Regulatory Commiasion Attn: Document Control Desk Washington, DC 20555
Subject:
Limerick Generating Station, Units 1 and 2 Relief Request for Performing Bolt Removal Requirements Gentlemen:
Attached for review and approval is Rolief Request No. RR-15 for the Limerick Generating Station (LGS), Units 1 ar.d 2, American Societ.y of Mechanical Engineers ( ASME) Boiler and Pressure Vessel (B&PV)Section III, Class 1 pressore retaining componen.t s, ASME Code,Section XI Examination Category B-P, Item Numbers B;5.10 through B15,71.
Specifically, we are requesting relief from aisassembling a bolted connection solely 'or perf orming a vl ual. inspection to determir,J if leakage is the result of corrosion of the bolting material as requirad by paragraph IWA 5250(a)(2) of ASFE Code,Section XI.
The disassembly of a bolted connection is not considered to be prudent in all cases.
In performing bolt removal, the situation exists that additional costs and radiation exposure may be incurred.
There also is a potential negative impact on plant performance.
Justification for relief is explained in the
.tached relief request.
We would appreciate vour cooperation in providing an expeditious review of this request, as we would like to have approval by the start of the LGS Unit 2 refueling outage.
The outage is currently scheduled to begin on January 23, 1992.
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11. S. Nuclear Regulatory Comm! salon October 5, 1992 Document Control Desk Page 2 If you have any questions or require additional information, please do not hesitate to contact us.
Very traly yours, 3{pg _llh.
I G. J. Beck, Manager Licensing Section Attachment cc:
T. T. Martin, Administrator, Region 1, USNRC w/ attachment T. J. Kenny, LGS Senior Reside ~t Inspector, USNRC w/ attachment f
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3 151 Prograin Appendix A 15 PaFe I 'I 3 111:1,11 7 isl:Q UI N I' N O. Itit l$
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IDl!NIliqCAIION OP COMPON!!NTS All Clau i preisure retaining cornponents, Code I!xamination Category ll P, item Numbers 1115 10 through 1115 "il.
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CODl! IllsQUlitI!Ml!NTS 1:ltOM _ WillCll !t!!!,lPI IS Ill!QtJI!S'il?l]
ASMii Section XI,1986 Iklition, I!xarnination Untegory Il P, requises a VT 2 visual examination of all Class I com[mnents during the conduct of liv. system leakage or hydrostatic pressure test. The purpose of the VT-2 examination is to detcet leakage. 'lhe acceptance standard for dealing with the results of this examination is contained in paragtnph IWib3522. 'this acceptame standant icquirrs correction of specific relevant conditions, to meet dw requircinents of IWil 3142 and IWA 5250i prior to continued service. IWA 5250(a)(2) indicates that if leakage occm at a bolted connectior the bolting i
shall be temoved, VT 3 examined for corrosion, and evaluated in acconlance with IWA.
- 3100, Itelief is requested from performing the deliberate halt ternovnl requirement of IWA.
4 5250(a)(2) if leakage occurs at a boltsd connection.
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- li,ASIN ItOlt Ildl.llilj The sequirement to disassemble' the bolted connwtion solely for. the purpose of.
performing a visual examination of the bolting-for conosion is not always logical.
llotted connectiom which experience leakage could have been reworked during the current plant or system outage. If the connection w,,s reworked, all associated bolting, whether oiiginal or replaced, wothi have been visually examined prior to remsembly of the connection, Additionally, this-bolting materii would likely not have been exposed to systern service, thereby minimizing the possibihties of corrosionllhis position is supported tu
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Appendix-A.15 page 2 of 3 Ill I.ll:l' lli:()UlWl NO. illt l$ KONII)J
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l by the ASMl!Section XI inte ptelatioti IN90 fl23, which was '., sued on Sepleinber 10.
1991.
Additionally, a portion of the pressure retan.nr bolting used in Clan I appl::ations at i
l.GS is nnute op' of stainlen ocel mateliah. Thew inaterints are not as soweptibic to corrosion (wastape) as are ratbon or low alloy materiah. Abo, since the nonnal Class I precure boundary of a llWR facility contains only deminctalized water, the chances of severe cotrosion me minimal. While stainicu steel bolting materiah are susceptibit_ to stress mitosion cracking under centain tonditions, detection of this type d corrosion on the bolting material is difficult using the VT.3 visual examination method 'lherclore, removal and examination of the bohing will have little significance.
1inally, if evidence exists which indic.ites that the lcakage fom 4 is not a preexisting condition and the leakage is stopped, the toncern for conor. ion of the bolting material is leduced.
The m3t and added radiation exponne anociated nith the te<piirement to dhaswmble and examine.the intting, along with the inherent need to repeat all or portions of the anoriated prenute test and the poteillial itnpact on plant operations,- far outweigh tue increase in safety sesulting from performance of this examination.
- IV. -
ElIllLN61ILi'l!OVISIONS -
it during the emeluct of a Scciion xl prenure test,; the vi 2 examination reveah a relevant con <lition as Ibted in IWil 3522, at a Class l_ bolted connection which has been in servicef the entire connection will be visually examined n$ing the VT 1 method. 'lhis examination will be condnoted to deterrnine the overall condition of the connection,1with
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respect to corrosion. 'lhe examination.will be conducted;with all bolting in-phice, under tension. The results of this examination. and additional faitors will be used to perfonn.
an evaluation of the condition of the bohed connection, Additional factors dhich mav-1 l
be used in the evaluation could include but are not limited toi type' of material 'used for the botting, the nature ofithe leak itself, the service age of the boltins anaterial, date of previous visual examination of lulting, sheduled maintcaance' for the subject - joint,:
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151 Program Appendix A 15 Page 3 of ' 3 111'111:l' ill' )UIWl' NO, 1111 15 (CON'I D.)
A results of ISI volumetric exarninations confittnation of leak stoppage.
If any of the factors uwd for the evduation inaicate a potentirl for degradation of the botting due to conosion,' then one twdt will be irmoved a.ed VT 1 (not VI'-3) examined j
for corrosion, and evaluated in acn.nlance with IWA 3100. The imit selected for removal I
and examination will be the bolt snoit likely to be affected by the subject leakage. When the removed bolt has evidence of degradation, all the remaining bolting in the connection shall be removed, VI'-l examined and evaluated in accordance with IWA-3100.
If the results of the evaluation indicate that bolting degradation is not expected, bolting need not be removed. A Vlil reextonination of the subject connection (in place, undct tension) shall be conducted at fl.e next refocling outage, unten the connection is icworked due to maintenance or modification activities.
lhe requirement for removal of only one bolt is supported by the fact that the Section i
XI Code reflects this concept in the 1991 Addenda. Additionally, the Section XI
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Committee is corrently developing a Code Case nhich will' provide for evaluation.of-leaking connections as an alternate requirement to IWA-5250.
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