ML20154H053

Forwards Supplemental Response to Licensee 960103 Submittal to NRC 850806 RAI Re GI-77 on Plant Design Drainage Sys. Encl Corrects NRC Records Containing Util Previous Response, Since GI-77 Has Been Resolved in GL 89-18

ML20154H053
Person / Time
Site:	Prairie Island
Issue date:	10/07/1998
From:	Sorensen J NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-077, REF-GTECI-NI, TASK-077, TASK-77, TASK-OR GL-89-18, NUDOCS 9810140064
Download: ML20154H053 (5)

Text

Northern states Power Company 1717 Wakonade Dr. E.

Welch, MN 55089 Telephone 612-388-1121 October 7,1998 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Supplemental Response to Generic Issue 77 Information Relating to Plant Drainage System By letter dated January 3,1985, (should be dated 1986) NSP voluntarily transmitted information in response to an NRC request for assistance dated August 6,1985.

Engineering efforts to respond to an NRC resident inspector question regarding some assumptions in the Prairie Island IPE have identified that some of the information provided in our January 3,1985, letter is incorrect, although based upon the revised information the conclusions of that letter are still valid.

The supplemental response in the Attachment is being supplied voluntarily to correct your records containing our previous voluntary response, since Generic lasue 77 has been resolved in Generic Letter 89-18. This correction is not reportable under the requirements of 10CFR50.9 because the corrected information did not have a significant implication for public health and safety or common defense and security, if you have any questions related to this supplemental response, please contact John Stanton at 612-388-1121 x4083.

Joel P. Sorensen d

Plant Manager Y

Prairie Island Nuclear Gene ating Piant Attachment 9810140064 981007 PDR ADOCK 05000292 P

PDR

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'I USNRC

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NORTHERN STATES POWER COMPANY October 7,1998 P:ge 2 c: '

Regional Administrator-111, NRC NRR Project Manager, NRC l

Senior Resident inspector, NRC Kris Sanda, State of Minnesota J E Silberg O

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l Attachment s

PRAIRIE ISLAND NUCLEAR GENERATING PLANT Supplemental Response to Generic issue 77 Information Related to Plant Drainage Systems l

The modified response to the August 6,1985, NRC voluntary request for "information related l

to plant drainage systems"is presented below by repeating the relevant portion of the previous response (January 3,1985) with modifications indicated by shaded text for additions and struck-though text for deletions:

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- Normal Drainage Design and Internal Flooding of the Screenhouse Figures 12,13,14 in Appendix A show where safety related equipment is located in the Screenhouse.

75!r 0;r!; cr' ! -^u^ted c'^re ^^r r!rrett" 995' 0" On!y ? p!rg crd her;r r f^r cr'd; re'eted 0;u!; r-t e&t be!rr> the ^^r B!rvet!^^ 995' C")..^'! the cr'ety

--5ted r;r p r** !r !^reted r^uth O' r^!u-~ r^r' E The berr crt a^^'!r et r!rreth" 979' 0" l

WPsnt's&ishh6Ufe[dontal65;thslsafet felagdbolfpli.Waterpumpifhon-safety I

Statid 66olin6Witeil pumps [firipr6tectl66"psmp57pla6{666de sir l circulating witsr DUmpsTind tiiVolin~g'idiesniEMplaht idrienh60se d6esinotiontain;any high snergy iysterWi;iildifi6EdJr[thifrairie'Isla6d OSAR' Appendix IU Lirge' failures 'o'f SpipeWalls f6r7n6defate; energy'fysterns.is'not part of the. original design basis for R(aldi;islahd&M6deistelshirg9)pstenfpipirig tends to'deve.16p~ijsmall_ leakage.at defect 166stf6nsibsforsilliigipigsWallfibit;dsiil6ps3The strength [of'matsriils U55d[iU365hipipind?syifsRc6ihpifed;t6;ihiiW6deratijheig93ontained in the EysMHs[Wil fi6d f6pr6pigatsflaps virfslowlp[if it'all.

Thssifetp'islatid 6coli6g~isatefyiirspsi6d isso6iated sq0ipinent;loca.ted in the pla6tiddinh6uislis?gihiiallp?m6Uhfid~ab6vithi1695'-01floofiilisitiori.}Alliof the safet9 felated idUlpMntllslidcatidMithl6 thssiteimil flo6d barrisf so0thiof col 0rnn fois,EOPipihiDiidgsis[sndfportionsl6f_the elictricalfcirc6its for'thisl safety] elated

~ Eful men {a@76cated l# the 670'-01basementlevel of thiscreenhouseZAll of the P

safstiffifatid ^ ele 6trical p6isii'sUppip;fesdsb tiis planticreehhouss'intif irf the bseiissNt2WM695l-01fl6cf[bD{J6 ors [ths6]Mab60i;thi67050" bassment

. fl65F3Milisilial~sLppilis]G6lthroUghll6ondditi~indicable;trapifdg[to tirrninati6n

.babihits[abovsith6l695'!01tI66i,iThiT6&bisisrslallfhin'itsie;;theles&Iof thstopof IIi!s.Cir661stl6dWatsM6ihiih6tofisxcept;for'the Diesel Driileri'Co61irig Wate.r Pufnpifdisi. Oil Transfe[RFmps1lodiUh6toFita'rter bo?

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Attachmint NORTHERN STATES POWER COMPANY l

Pag 3 2 l

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1 The Screenhouse floor drainage system consists mainly of a 4" diameter pring. The drain inlets are medium duty cast iron type with threaded outlet and flashing ring (J.R.

Smith Mfg. Co., Fig. 2110) unless otherwise noted. The drains discharge to the trench that runs along the south end of the building in the basement which slopes to the sumps. The drains and piping are shown on drawings NF-39298-1 & 2, and NF-38350-4,in Appendix C of this report.

l The Screenhouse is served by a collection sump 16'x6'x4'-6" deep (33200 gallons).

It is shown in detail and location on drawings NF-38350-2, -9 and -10 (included in Appendix C). The sump contains two 50 GPM sump pumps.

i Sheu!d one of'he ner refety re'2ted !per !"'"!r 2rer f2!!,'he rump !r prc'!!ded "'!th

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2 h!gh !c'/c! c'2r-"h 2'2 me !a 'he Cer+re! 900~ The '/c!ume of'he b2rement cree of *he rcreer" cure !r ruMe!ert!y !:rge te c'!c'." +he Oper2 tere "~e te !re!2te +he bre2 before 2ny of'he refety re!:ted equipmer* "!cu!d be end2ngered.

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Duringa p6stUlated fail Ore of s Circulating 1 Water pips, the screenhouse hasement, spproximatelp 365100'lwould fill to ajdspthi.of 16[within 3 minutes / The Circulating

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Watbr~pdr6p; mot 6i,Tiii6t6r tsiminalsiand'exciterM6uki be_ submerged, resultihg in a pufnitrip2ThliM60.ld'stop'thslwatei souFce befoie the cablssiab6vs the top 6f.the

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Circ 61sti65 Witsr?UirippioloF51eVatiohjWsre flo6dsd2 PostUlsted failu'rsof an 6ther pipin@W6UldlyisidfmUch]IoWstfisfrats;s;whichMionld givs the operat6fsLsmple time (6isojsts the~sffs6tediy5 terns l.

The Dissel Driieh Cooling Watei Pumps Fuel Oil Transfer Pumps, local motor starter Fox'co0ld bs flooded bpls postUlatsd failure lof ths Circulating Water piping. These

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birFUits' arijUs[over fdur feet abss..ths basemsnt floor elevation.j Potential flooding J

of th5ss; circuits lwould prepent bUtomstic, transfer of fuel frorn ths Diehel Driven C66ind1Wbteffdmpf6 I Oil Storsgs:Tankiltd th6Dsy Tsnks5 These Day Tanks tibileisOfficientjcalp;scitpfel6w thb low lessi alsrhil point to piokids f6r ssven ho6rs of disssi driviriT6ooli65 watef pUinpl6peration7lri;sdditj6n, thsse' Dsp Tanks can.bs mandalli'slignsd_t6lthe safsty relsted fuelfoil storage tanks' fof the Unit 1 Diesel Generat6rs.5This;is"dsscribsd Iri uSAR section 2.'4.3.5.

The plant scisenh66sefsdmpl5h6did fem 6ve all.lsaksgs frorn.sxtemal floods or

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intsmsl;cornp6ribntsRThe sump is provided withLa high level. alarm'which alarms in thsLControl. Room.[if Isskage;were to esceed.the.' nmp pump capacity, the large

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s s0^rsi shd;thsrithe lsigir' sci.eehhduse.bsseinen't';wdUld ' slowly fiJiaThe sump 16 vel blsihiifue[oi[diltink'IsQel'aliriHTirid;th's eight hour'sipply in the dsy, tanks allow thi~6perat6fitiniilc[takisri Lictl6ris;necessarplto'rnairitalri cooling ~wster pu'mp 6psisti6ri;

Attachm:nt NORTHERN STATES POWER COMPANY Prg3 3 Based upon the above revision, the conclusions of the January 3,1985, letter are still valid for'the screenhouse. These conclusions are repeated herein:

"... the drairage systems for these buildings are designed for equipment leakage which occurs during normal operation of the plant and not for large internal flooding conditions resulting form major failures of systems having relatively large capacities of water."

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l "However, the buildings have the capacity to s ecommodate large internal floods since it l

takes time to increase water levels to an elevation where nuclear safety related equipment could be affected" (functionally). "It has been shown by the various references that the operating staff has enough time to react to isolate the systems causing the flood before rising water levels can sustain any" (functional)" damage to nuclear safety related equipment."

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