ML20084D378

AO 50-237/75-25:on 750116,Noshua Silver Duct Tape Dropped Into Reactor Vessel Annulus from Feedwater Sparger Work Platform.On 750516,decision Made to Start Reactor W/O Recovering Tape Rendering Tape Drop Reportable

ML20084D378
Person / Time
Site:	Dresden
Issue date:	05/23/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20084D363	List: ML20084D361 ML20084D378
References
323-75, 5944, AO-50-237-75-25, NUDOCS 8304110129
Download: ML20084D378 (5)

Text

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[ Comm wulth Edis:n tionat Plaza. Chicago. til.inois

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,,' Chicago. Illinois 60690 Ft 1 Addres ., ply to: Post Office Box 767 -

EE3 Ltr. i:3PN75 Dresden 1:uclcar Power Station R. R. //1

.: orris, Illinoic 6'M ~.

May 23, 1975 4 *

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d Ecd / /7 Y.h 7 . Ja.mes G.1:eppler, Recirnal Director M

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Di: ectorate of Recalatory Cperation-Region III 4 .. -

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Rcrercncen: 1) Reculatory Guide 1.16 Rev. 1 Appendix A

2) Kotificaticn of Region III of 'J. S.1:uclear Regulatory Cc=ission Tele-hone: 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br /> on 7.27 16, 1975

3) Dra ring 1:umbe" ':-26 T.cpert E rler: 50-2f'7/19'5 herort D tto: ..sy 23, ". 9*75 0? cur cnc? .'nte: Jancary "6, 1973 (Fay '6, .'

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A roll of "achua tape ::as lost in the Unit-2 re .etor. All cfforts to retrieve the tape ::ere uncucceccful. This event reculted frc:.* in?dec3uate inp? cr.cnta. tion of procedural controls.

CO!!DITICN3 PRICR TO CCCURRF2:CE Unit-2 was chutdcun for its third partial refueling outage.

DESCRIPTIC: CF CCCURRC:Cis On January 16, 1075, a roll of Nashua Silver Duct Tape (Type 357), two inches wide and about 6 inches in dicmeter with a three inch ID. hollow core, was l inadvertently dropped into the Unit-2 rcactor vessel annulus from the feed- l water aparger work platform. It was observed oplaching into the water by at l 1

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, 1 Mr. James G. Kepp)np May 23, 1975

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leant two people in the area. Efforts at recovery of the tape were canducted periodically between January 10, 1975 a:rl F.ay 5,1o75 with no cunecac. On

!*.ay 16, 1975 the decision was n.ade to ntart-up Unit-a without recoverinc the tape. 10, that point, the event. becan.e an incident.

DpSICFATIC?: OF APPlaIO:T CAU'E OF CCUldC:lE (Procedure Violation)

The apparcnt cauce of the occurrence was the violation of the feedwater sparcer repair procedu"e (!:0. I.l3:t . ^). This procedure stat er in part

". . . All hand toolc and ecuip..ent ubich during uce have the potential to be dro ned into the RPV shall have 2 nnyrds attached. . . .".

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The safety concern uith the 1 cot duet tape ic the potential for flow blockage nnu cu'cnequent fuel danare.

A d< tailed ctudy on f1cu bleckat e in a :'.3 has been made in GE Topical Renort (1:130 J10174) . :.ich ic en file in the Public Docun.ent Rocm. As stated in that report. l'accd on analyres of hi; power dcnci ty futd operatinr- at 15 5

w/f t* :

a. In rould take more than ' E inle: aroa blockace to cauce a .f.,FEt lecc than 1.C; therefore, no fue2 rod da: 2ce vould occur unlecs core than 9C;'

bloc'a;e coeurs,

b. I f t: , bic^? e rcre m: t'-n Y ,, cind ~elt 2nd fuel err 2U ng e :uld :caur.

ric uculd 1cUi tc hi , t "ndicticn conec:t by Ce . ain atent: S ne '*cdia',icn

iterc Ubich re

1d neram end w lnte the reactec. C f f r. o d e c e r, eor i ' ..

loc: than E C:iD 20 liMtc.

c.  ::e dra;f uauld 02 ur .; nr, i tuu'2 -linennt to 11.o bund . . 4 th t;u. fl e-bi ca .od.

• Unit-2 nac a m ui:rx L"fi.: l ir.it o f 17. '.3 E.7/ft.

At t' r. quest of the .3tation, Cc; .on ealt ':dican's Cperational A:ni"ci:

Departw nt (CAD) ccnducted tents on rn rerentative canplec 0; duct tcpn at cirm: lated preocure and temperature. hvide: tee to date indicaten that the rd ccing roll of duet tape my not dinintegrate and break into c=all particles. In licht of this evidence, an analycin was considered prudent to justify operation of t!.c unit. The lont roll of tape precents an unlikely but neverthelenn potential ficw blockage problem.

An increction of the prinary cyntea wan trade without locating the rr.icainc tape.

'.'.:en the tape una dropped, the recire, pu: p cuction and discharge valven were cloced, "A" chutdown cooling punp waa in operation, taking cuct. ion from both the "A" and "B" recire. loops. Since the feeduater aparcer repair platform uns in place, it can be ccncluded that the tape uan dropped in the veccol-to-chroud annulua. Therefore, the tape in either in the recire, pipind, the shutdown cooling cyatem, or the reactor water cleanup synten.

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Mr. d!amec OcppEer -p mgya, vym e

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A thorour:h inspc'etion of the recire, cycten was mLJ after opening the recire,pu p cuetien valvec. Thic incpecticn was made incide the pipin o l cyctem with a TV car. era. The miccing tape vac not fcund. (

The reactor water cIcanup cystem wac not in operation at the time the tape wac d"opped. Therefore, it ic unlikely ti.at the tape is in the cleanup cyctem proter. Frcm the cleanup cyctem, the tape has no path to the reacter veccel; it would te stopped in the domineralizerc.

The meat likely place for the tape is in the chutdown cooling cystem cince it wac in operation at the time the tape wac dropped. It is poccible that the tape rac nicred during~incpection of the annuluc recicn. Therefore , in order to reach the reacter, the tape would have to pacc through either the chutdo<m cooling rump cr the ("A" or "B") recire pump.

The tape recidual vould have a maxir:um 0.D. of three inchec if paccing through the recire, cyste:: cr cne inch if paccing through the chutdown cooling 0/ stem. The jet ptrnp noccle orifices are three inchec in diameter and the cPratdctm cooling cyctem heat exchanger tubec are one inch in diameter.

CAD tecta nave indicated that the tape breaks doun into a git.tincus cubstance after neating to 545*. Therefore, the pcccibility exicts that cuch a tape recidua'. (no ; reater than three inches in diameter) could be deposited ir the lcwer plenum.

Again, taced en the thorougP inspection of the annulus area, it is unlikely that the tape entered the rceirc.cyctem. The chutdown ecoling pump cucticn and the heat enchanserc have also becn inspected. Eut since the chutdoun cyctem uac in operation whon the tape wac dropped, it is concluded that any tam reciduc 5:culd ~cct prctably te limited to a one inch C.D. , entruded fro:-

the shutdern ecoling cycten.

In eit'.er case (i.e., three inch or one inch 0.D.), tPc recidue entering t >.c i c u r el c nt = han to preceed alcng the intricate path tFreuph the raide tutac cefore r:acF"r- the channel :nlet. The guide tubes leave a .ninimum

"- eno m4 err-hsU incher and a maxEun w of fcur and one-Psif inchec.

The actim. Ocniicaratic:. is il]uctrated en pa;e a of 'R-1 '174 The teate rur at FAD indicate a arecensity for the. Laue racidue to ctian to anything u# t' - 4

.ch it ec:cc i ecntact. Tne tenacity or the recidue, the high

'/.: vulence in the an a, arJ the hcat of tLe reactor envircr=nt would likely farac t..e recidual :nto c=nller partc. Furtbem. ore, if a three inch Jeciduc

etc

Pr aah the f et pu~p no

'zle, the high do.mward volocity component wil tend to %c7p it en the bottom of the reactor veccel. Tne factor that will detamine uimther nns recidue uill be cwept up off the bottom in dependent on the radin] component of the velecity and the component's doncity. Calculatienc of the average vertical and radial velocity components welv v.de for Dresden 2 (L*EDO-10174, tabl( ~j .1 ) .

'..'aile it in poccible for the tape recidue to be cuept up toward the bundle entrance, the following factore tend to reduce the ir' pact of thic faat:

(a) There are very fm locationc where the radial velocity would be hirh enough to at;eep the piece off the floor of the vencel. Thece locations are directly in line uith the recirculation line outlet near the periphery of .the guide tubec and the narrow one and one-half inch cap betwocn guide tubec. (b) If in thic particular inctance the residue were aucpt upward, it is very unlikely that it could contact or block the fuel acccmbly orificec i

1 i wo CJ

Mr. James G.1:eppler 4- May 23, 1975

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'v' v cince they are vertienlly oriented, i.e., they are perpendicular to the flow of sny residual matter. (c) Any recidue which contacts an orifice would probably be in cuch a physical ctate that it vould extrude throuch or (due to further disintecration) cirnly pacc throuch the orifice. The recidue vould then appreach the nocepiece c uards which offer three ceparate paths to the louer tie plate. Any residue which reached the nocepiece cuardn could not be larce enou h to bicek all three -aths. There fore , cooling water will alt:ays ha'e accccc to the full bundle. (d) If the r cidue vere to block the 3/8" holen of the louer tie place juc; above a por Lion of the nocepieec, cooling flew could still reach the affected fuel sccemblies through adjacent tie plate helec.

It is poc ible, neverthelens, fer n tape recidue to reach the louer tic plate

of a fuel bucdle. 'lhether . the rcrinue partially cloca the tie plate, deposita ac crud en acte fuel accerblitc, or ic stopped on the firct fuel bundle cracer, the norct cace in Incal critical hcat flux and overheating, danacinc the cladding en four fuel rods or lecc. Since recidue could not significantly reduce the flow in ene entire bunc le, it ueuld not cauce dccrndation of the '. cat trancrer con-iitiens in other arent of the Ibe] bundle.

Therefore, even thouch it in pctrit'.e for r.inor blockar;ec to occur if the tapa recidue recchcs the tie plt'c and/or enters the fuel bundle, only the life of a fc'.. fuel accerblice cculd be affected.

The fina' dieroof.tien of the drep::cs! tape reciduc ic throu,-h the reactor

' T ter ele cnu~ cycter uhic'r prov;.dce centinucus Furification of the recirculation flru. The renctor water cleanup ryctem maint tine high recetor unter purity to limit che:.ieci and corrocive acten, thereby lin.itin;; fou inc and derocition c:. y at terv:'er curfc cc c.

Thc tacia ec.21urien %nt en:. Pe c"--- . frem t1:e rece:Mn: mccu~cien ic that s - is c.  !!- * .rci ,c c t" r.: tt . tr- rer! 6:e could et.uce ricche"r of 4.,,.

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An a reruit cf thir an-Iyr.ir, it :r eeneluded that it ir ne t only cafe tc ctart up, but that full pc. cr renetar operation to 100, ic not precludci ac r result of the niccinf tape.

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. - . a. :/ .- epnencon S';perintendent El'S: cmp Fi?c/NRC

w Jasse3 G. KePPicr Kegional utrect:r Direatproco ef (j4 1ctcry Operctiens .. g 7 5 Rej on III d F.S. !(uclear Regulatory Cs aission. , og E-?d 19 i 799 Roosevelt Road - ~ L. '

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Glen Ellyn, IL 60137 37 gju )

CC: .

Bernard C. Rusche, Director

' Directorate of Licensing W.S. Nuclear Reguintory Cociaission Washington, D.C. 20555 i

SUBJECT:

DFA- /9 , Dresdets Nuclear Power Station, Unit E .

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To Call: W/G/7 C 3 o B. B. Stephenslon, Superintendent i CE 858-2660x16 (auto) 4 t DC 9-1-301-492-7617 (auto) - on 6 Dresden Nuclear Power Statioct I W - 815-942-4449/4321 Couroonwealth. Edison Company R.R. #1 , l Station Irist: Originator (copy) # ** Incident File (copy) Telegram Filo (original) Telephoaa: 815-942-2920/2921x212}}