ML20084L154

Updates AO for Discrepancies Noted in 740415 Insp Re Jet Pump Failure.Initially Reported on 740425.Caused by Excessive Vibration.Repair Work Completed by 740625 & Design Mods Incorporated

ML20084L154
Person / Time
Site:	Quad Cities
Issue date:	07/12/1974
From:	Kalivianakis N COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084L155	List: ML20084L154 ML20084L157 ML20084L179 ML20084L184
References
NJK-74-141, NUDOCS 8305200293
Download: ML20084L154 (5)

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w ,.w 11r . J ohn F . O' Leary, Director Directorate of Licensing Regulation U. S. Atomic Energy Commission

, Washington, D. C. 20545

Reference:

Quad-Cities liuclear Po.cr Station, Unit 1, Dorket No. 50-254, DPR 29, Abnormal Occurrence Report Letters of April 25, 1974 & May 30, 1974.

Dea r 11r . O' Leary:

The purpose of this letter is to provide you with further information regarding the above referenced Abnortral Occur-rence Report. The previous letters have described the initial findings and planned Japairs related to fcilurcs of several jet pump components of thc Unit I reactor.

Several design changes were made to the replacement parts to facilitate remote repairs while restoring the jet parrp a u r cr:blie s to the ir origi na 1 functiona 1 requireraents .

'/ne h r s ic jet pump design retaains unchanged. The design changes were incorpora ted primarily in assembly features and techniques.

All repair work to the failed jet pump components was com-pleted on iTune 25, 1974. A discussion of the final repairs f ollo.:s : @)

1. Restrainer Gates - Restrainer gate assem'olies for all 23 jct pumps v:ere repl'ced with nev, assemblies .

The entire assemblies were rep] aced rather thEn just the faileS bolts in crder to minimira racia-t .i cn ci:posu re to the mJintenance personnel. Jet pumps 5 and 6 recuired modifications to the stand-ard restrainer gates as is discussed belott.

2. Rastreiner rate Uedcms - The restrainer gate t:Cdges for the ncs assemblics are slightly larger (thicN r) to assure that the installation tole ra nce is inintained. A ll newly ins ta lled wedgen met the sptcified installetion tolerance.

3. Rortrain?r G 4 nelt Ke c m r s - The r ede s i cine d 1

restre in2 r gr.e nolt haaners were insta lled on 1 > <'

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all 40 restrainer gate bolts. Two tack walds par gate bolt keeper were applied instead of the one weld specified for the original assembly, to provide a greater margin of integrity.

4.

Jet Pumo 5 Restrainer Gate - A standard restrainer gate required special modification in order to facilitate installation on Jet Pump'S, The stand-ard gate was cut in two at a point 450 from the center line of the wedge on the side nearer the hinge pin. A spacer block was then welded be-tween the two parts in order to provide an off-set of approximately 1-3/8". The offset was necessary-to compensate for one side of the jet pump hold down bracket which was bent.. Because of the very close proximity of the hinge pin to the inlet mixer of the jet pump, a new design bolt .aruS keeper were provided in order to avoid interference of the bolt and keeper with the mixer.

5. Jet Pump 6 nostra iner Gate A standard restrainer gate was also modified for installation on Jet Pump 6. An extension arm was added to the gate on the hinge pin side. The extension arm had a locator screw assembled in it to replace the locator block and adjusting screw that were broken off. Tha ext onsion is assembled to a new ria"'gr g"ta belt and the caluLine Linge pin, and is secured by a new design nut. The nut is prevented from rotating by a keeper which is tack welded to the extension arm. The bolt is ~~

kept from rotating via a Right-Hand and Left-Hand thread design feature. The locator screw was adjusted to mate with the belly band on the inlet mixer assembly and tack welded in position.

The second locator screw on Jet Pump 6 had been found with a broken tack weld and was not properly positioned in its locator block. This screw was returned to its proper location as indicated by the original tack wald and a new tack wald was applied.

6. Jet Pumo 7 Locator Screw - Jet Pump 7 was found with one locator screw missing from its mounting block. A new locator screw was designed to facili-tate remote assembly and installed, adjusted and tack welded in position.

7. neam noit Petainers - Beam Bolt retainers were found missing from the beam bolt assemblies of Jet Pumps 10, 15 and 16. These retainers were not replaced since their only function is to prevent the beem bolt assembly from falling from the inlet-mixer during assembly or disassembly.

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Any future disassembly of those inlet mixers will require that the beam bolt assemblics be removed as separate assemblics.

8. Beam Bolt Assemblies - The beam bolts for all 20 jet pumps were retensioned using the procedure developed during the jet pump repairs to Unit 2 in 1972. This procedure requires a minimum bolt rotation at a torque value of 50 f t.-lbs. which provides assurance that the specified tension is applied.

Following retencioning of the beam bolts, the beam bolt keepers were secured with 4 tack welds per keeper instead of the original 2 tack welds per keeper to provide a greater margin of integrity.

9. Jet Pump _7 Instrument Li ne - A previously repor-ted failure of the flow instrument line for Jet Pump 7 was identified as a severed line during this outage. Because of the engineering and mock-up required to develop the necessary tools to repair the instrument line, the fix for the severed line on Jet Pump 7 was not available for the current outage. It is planned to operate .

during the next cycle with the instrument line Oc it c ne1, end to Pry en repair it during tha next refueling outage.

10. Missing and Loose Pa rts - Table 1 is a complete c-index of all parts known to be either missing or loose in the vessel along with their disposition to da'te. Inspection of the Table shows that the following loose parts remain in the vessel:

A. 1 Retainer for beam bolt " L" Shaped piece 1/8" thick, 2" wide, one section 2" long, one section 3" long.

B. 2 Bolts for above retainer 3 /4 " long x 1/2 " d ia .

C. Small piece masking tape 4" x 2" D. LPRM Spring reel guide piece 1" d ia . x 2" long E. Short piece of walding rod 6" long F. Sleeve from ref ueling chield-cylinder 3/4" dia .

gate (cattle chute) 1/2" long 7.n obvious concern involved with these lost pieces in that asscciated with potential fuel bundle flow

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blockage . A G.E. Topical Report (1) states that it would take more than a 90% area blockage to cause a MCUFR less than 1.0. The like lihood of the pi.eces under consideration significantly blocking the fuel bundle flow is very small. Be-cause of the high density of the pieces involved, it is expected that were they to be introduced into the reactor lower plenum, the velocities there would not be high enough to lif t the pieces to the core support plate. Thus, the probability of fuel bundle flow blockage is very small. (2)

If the lost pieces become fragmanted into small pieces, these could become lodged in the fuel bundle spacers, which could cause local cladding failures. However, if cladding failures do occur, the resultant radiation releases wouldthe be appro-sensed by the plant radiation monitors, and priate actions would take place. The health and safety of the public would not be jeopardized as the of fsite releases would remain within the 10CFR20 limits.

The conclusion of the analysis of the inspections and repairs of the failed jet pump components is that the failures ware fatigue failures caused by excessive vibration. The vibra-tion was due to several of the jet pump beam bolt assemblies not being tencicned to meet thn original design requirements.

t e o u li a rc.c nt s Fina lly , the failurc to mcct the cr2g'm i duivo is attributed to improper field installation of the compo-nen,ts involved . y-.

The Unit 1 refueling outage remains in progress as of this date. Startup of the Unit is tentatively scheduled for July 16, 1974.

Very truly yours, COMMON /?EALTH EDISON COMPMW QUAD-CITIE$ NUCLEAR PONER STATION

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a N. J . Kalivianakis Station Superintendent NJK/ REQ /sa a cc: Region III, Directorate of Regulatory Oparations J. S. Abel Attachmont: Table 1, Index of Missing and Loose Parts NSDO-10174, May 1970, G.J. Sca te na , " Consequences of a (1)

Postulated Flow Blockage Incident in a Boiling Wa ter Reactor".

(2) Quad Cities Station, Unit 2, Special Report No. 2, "Je t Pump Operability".

(3) Supporting Documentat ion - Quad-Citics Station, Work Request Numbcr 1802-74. .

QUAD CITIES HCC:. EAR PONER STATION U20:T 1 y>- SPRIMG 1974 I.UFUELING OUTAGE ,

g INDEX OF IIISSJHG AND LOOSE PARTS PART ORIGINA L DATE OF DATE OF STATUS

• DISCOVERY RETRIEVA L DISPOSITION .

JP 5 Pestrai ner gate bolt head Missing 4-16-74 By 4-23-74 To GE - VNC JP 5 Res traine r ga te bolt head Missin_g_ 4-16-74 5-25-74 To GE - VIC JP G U :rtrainer gate bolt head N i s s i t3q_ 4-16-74 5-2 5 - 7/'

JP 5 Rentrainer bolt keeorr To GE - V?]C Missinci 4-1G-74 Bv 4-23 -74 To GE - V"C JP 3 Pastra iner bolt keeper 4-1G-74 By 4-23-74

.i. . _M i s._s__i .n ~t To GE - VNC UP 6 Po. trainer bolt keoorr Missing 4-16-74 5-25-74 To GE - VICC J P G 'c; e d a -

Mianing 4-16-74 Bv_4-23-74 To GE - V?!C JP 6 0ladaa bale M i n s i nci 4-1G-74 Ev 4-23-74 To GR - VNC L. T D G '..cdo.- coring Minninn1 4-16-74 Bv 4-23-74 To CE - Vi!C

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d r:o haic (la ter veri fied f rom J P Sl L P. . : 1 e nd x onnocLor Loont 4-16-74 Ev 4-23-74 To CR - VNC

~~ ~ ~ ~ ~ ~ A 11 Of f 4-20-74 5-20-74 Fue1 Pool JP 6 Enm. Lor block l Misninci 5-22-74 5-25-74 To GE - VNC screw 5-22-74 f' JPJ P 6 Locator 7 r,ctator blockblock a d -j adiustin u s t ing s c i. ew Missint:

Minsina 5-22-74 5-25-74 To GE - VNC 5-23-74 To GM - VNC JP 10 Pat ~nar for b?an bolt Missina 5-23-74 5-23-74 T_o_ G E - V__N_C_

Retairar for beam bolt (la ter verificd from JP Loose 5-23-74,J 5-23-74 To GE - VNC Rotainer for beam bolt (later verified from JP 15L_l Leone 5-23-74

,J .. P 10 neit for above retainer 16)_I M i s s inci 5-23-74 5-23-74 To GE - VNC

.JP

- Li Bolt for above retainer I Missinc] 5-23-74

'JP 16 Bolt for above retainer _

_[ Misning 5-23-74 i M21 ding Rod  : Loose 5-23-74 lFi]a r-(_gv li nd o r [la ter ve r: fi ed as part of vib. inst.)__

Leone Loose 5-23-74 5-23-74 5-23-74 5-23-74 Fuel Pool To GE - VNC h-Roll duct tane .'lisring 6-1-74 6-23-74 Radwaste Sa Fe ;v c1io froin Cha in Fu11 Hois t Mi_ .< ing _ _6-12-74 6-22-74 Radwa s te

[ Pin from above sa fe ty clip Missing 6-12 74 7-1-74 Radwaste M . :#. j na t a nc 2__sm. a_ll

- - - - ci e ce Loose 7-1-74 G r r i r.c Roel T,PRM naide niece  ;

Missing 6-29-74 S i n ew f ro.n ca t t le chute _ . _ _

I M ia n i n g__ __G-2_4 -7 4 __

• Mi sing means not in normal location and unaccoun:Od for.

Loose means observed, but source unknown.

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