ML17252A963

Letter Regarding the Inspection of Bergen-Paterson Hydraulic Shock Suppressors at Dresden Unit 3 and the Revelation That 41 Snubbers Were Inoperable and Exhibited Overall Integrity

ML17252A963
Person / Time
Site:	Dresden
Issue date:	11/02/1973
From:	Worden W Commonwealth Edison Co
To:	James Keppler US Atomic Energy Commission (AEC)
References
WPW Ltr. #817-73
Download: ML17252A963 (4)

Text

Ccmm~~weln Edison .

One First National Plaza, Chicago, Illinois

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I Address Reply to: Post Otiice Box 767 t

.I Chicago, Illinois 60690 WPW Ltr.f/8i 7-73 .Dresden t~uclea.r Power Station *'

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• R*. R. ;n Morris, Illinois 60450 ****-**-. ----. --*

November 2, 1973

,*I 1 I Mr. Jomes G. Keppler, Regional Director

• .Directorate of Regulatory Operations-Region III

• U. S.* Atomic Energy Commission * * - * * *1 ** ' .

799 Roosevcl.t Ro.ad *

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Glen Ellyn,_Illinois *60137 I ..:

• I

SUBJECT:

INSPECTION O!i' IlE~GEN-PATERSON HYDRAULIC SHOCK SUPPRESSORS --~-*----~------*------,

. AT DRESDEN NUCLEAR POHEP. STATION l.mll' ii3 t AEC DI<T 50-249. . . " . ** . .

References:

1) *Directorate of Regulatory Operations. Bullet-~) .. . ~,

. . *. . . . . I l 2). Letter from Mr. D* J. Skovholt to Mr. J. S. Abel dated *

• October l, 1973.

__ ;<;rG~,' .** . '~ :. *.

--.'>~-*:~. ->::: \3)- Notification of Regfon III of AEC Regulatory Operations Telephone: Mr. F. Maura, 1725 hours0.02 days <br />0.479 hours <br />0.00285 weeks <br />6.563625e-4 months <br /> on October 29, 1973. *

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Dear Mr. Keppler:

This letter is to report information concerning the station's second inspection of Bergen-Paterson hydraulic shock suppressors .on

. Unit {!3 * . The unit was shutdown on October. 27, 77 days after the initial snubber outage, to *perform a second inspection ao required by Di.rector.ate of Regulatory Operntions Bulletin 73-4. The attached*list contains piston*

• rod extensions,, and fluid level indicator positions found during this inspection.

The inspection revealed that 41 nergen-Paterson snubbers on

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Unit ti3 were operable, and e;:hibited.overall*integrity. There were two*

snubbers in the drywell (I.D.1126 and 27) that had no .oil level indication on the snubber accumul~tor. They were removed from *the* .drywell for inspection and repair.*.

• The subsequent disassembly of these two snubl:>ers revealed such a low oj:l level that it .is questionable that they were operable.*

Sev~n of the operable snubbers had* low oil* levei indication on the snubber accumulatorc,. but* the oil level was no_t low enough to consider them !~operable.

Three of these seven (I.D~1F9, 12, and 25) had significantly lower oil level than the others and were removed from the drywell for more thorough inspec-t ion and testing.- It is believed that the lo~., oil level in the oth.er*four .*

snubbers (I.D.1113, 28, T7 end Tl5) resulted frOO! improper filling duri?ig

• the initial inspection and overhaul, since no.fluid leaks were evident.

The oil level in these four snubbers waD inct:eascd prior to resuming :power operation.*

NOV 7 1873 -~.

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• • 'A* *

• Mr. Jnces G. Keppler ~2- Novc?!lber 2,, 1973

. Snubbers 1125, 26, and 27 were disassembled, repnired arid tested satisfactorily prior to returning them'to their original locations;

. ln!:pection of snubber 'ff25 revenled that the bleed screw "O"-ring ri.nd most*

of the "O"-ri~gs on the manifold ::lsscmb}:ywere brittle £nd broken. In

.....

• addition, the head senl was flattened and broken

• Inspection of smibber fl26 revealed th:!t the bend Deal was flnttened, thct the rn::mifold "O"-r!ng w.:is broken,. ond that nost .of the

• se::ils in the ~nifold :lcscnbly war~ brittle~ but int<?ct. The oil level

• ... *indicetor wns broken durin[; c:!ioa!lst:?mbly. t*1hich. n!:?.ccocitotcd replocern~nt of the indicator piston ond the acct!:!lulotor *cylinder *. !n cdqj,.tion, the pfoton rod cylinder, the piston ri~gc pr.d. the accu!:!µl_ator s;>r:ing were re~laced *.**

Inspection of snubber 1127 revealed a faulty heod seal, brittle.

seals in. the ~:lnifold ossembly, with some broken, and a .c~ll scratch on the piston.rod cylinder. It could not be deter::!ined whether the* broken

• "O"-rings in the three snubb<?rs that were overhauled were .brok~n during disossern.bly or were actually broken during .routine operation.

Since no.oil leakage was discovered in the examination of snubber if9,.'it was filled with oil, tested.satisfactorily, .'.lnd returned

.. to the drywell. . Inspection of snubber #12 reve.sled e damnged "O"-ririg*

. * * - . on the bleed screw.. Following replacement .of the bleed screw 11 0 11 -ring, the snubber lJ<?S fiiled with oil,. tested ~at*isfactor*ily, and returned to

• .its original* location. .*" '.~*

• All seals removed were untreated polyurethane and all riew seals installed were ethylene-propylene,_ with the exception of the accumulator seal and the piston rod packing -washer, which were untreated polyurethane.,*

Eleven Grinnell*snubbe-rs>> located in the turbine and isolation condenser pipeways, were inspe:ct~d to supplement the above deccribed inspection. All were oper3ble, but one of the:Grinnell !;nubbers had low

oil indication. It was filled with oil end will. be repaired or repleced et a. later date due to its*non-safety rel~ted function.

• A permanent program for the modification and periodic reinspect ion of hydrnulic. shock suppressors has no~ yet .been established. This program iS being developed through the efforts described in our letter of October

• 15, 1973 concerning the Unit #2 inspection.

Sincerely, w~ P. Worden i' Superintendent

• WPW:do cc: *O'Leary

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• AEC Corr. /IV . -.'

• SNUBBZHS IN DRYWELL

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Fluld Le~el In1ic<.*Gro Position (in .j 1 3.00 3.50 ..

2 - 3.00 3.00 3 3.00 3~00 4 3.00 ,. 2.00**

5 3.00 - 2.50 6 3.00 2.50 7 3.25 3.50.

.. g 3.00 3.00 9* 4.50 *

• 6.co (low)

. 10 -~

3.50 . 3.00*.

11 3.50 4.co 12 4.50 *6.00 (l0t*1) 13 3.* 75 .*

• 4.50 (low)

. 14  : ,.3.50 3.50 15 4.00 3.50 16 3.00 3.50 17 2.25 *- - . ;.-,

2.00 18 3.00 -:-. 2.50 19 3.25 - 3.0b

. 20 3.25 2.75

. 21 . -. . 2.00 . 2. 00 22 4.50 3.75 23 Jo .. *. 2.50 . ~*" :...2.00

... 24 2.75. .. 1.75 25 " 3.50 "6.oo. (low) 26 1.50. Mo-G Visible (Inoperable) 27' 3.50 No*~ Visible (Izioperable)

• 2a 2.25 3.25 (l9w) 29 2.25 '* *. 1.25 30 2.50*- ., l.50 .

31 3.25 *.:., '* 3.00.

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.tr * *** <...

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• SNUBBERS ON TORUS

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... s*::.::.t.ion..J.& Pist.cn Roo Po~_d.tio:i (i.,"'1.) Fluid *:r.evel *Indicated *Position * (in'.)

2 3~25 3.50 3 . 3.25 3.75 4 - 3.25

., ,..~

• 3.75 5 *3~25 J. '"

7 *3.00 4.25 (low) s 3.25 3.75

.. '9 3.50 3.75 10 3.25 3.25 12 3.00 3.00*

13 3.2.5 3.CO 15 . 3.25 b,.00 (low)

'16 3.25 - 3.50

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