ML20084R739

AO 50-249/75-01:on 750104,insp of Bergen-Paterson Shock Suppressors Revealed Eight Snubbers Low on Oil W/Two Considered Inoperable.Caused by Pinched O-rings,slight Deterioration of Seals & Scratched Cylinder

ML20084R739
Person / Time
Site:	Dresden
Issue date:	01/16/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
32-75, AO-50-249-75-01, AO-50-249-75-1, NUDOCS 8306150527
Download: ML20084R739 (3)

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Dresden Nuclear Power Station' BBS Ltr. #32-75 R. R. #1 Morris, Illinois 60450 January 16, 1975 Mr. James G. Keppler, Regional Director Directorato of Regulatory Operations-Region III U. S. Atomic Energy Co::niccion 799 Roosevelt Road Glen Ellyn, Illinois 60137 SUBJET: REPORT OF AP"0R'aL OCCURRE::CE PER SECTION 6.6.A 0F THE TECHNICAL SPECIFICATIC:3 '

HYDRAULIC PIPlHG RESTRAINT FAILURE

References:

1) Regulatory Guide 1.16 Rev. 1 Appendix A

2) Notification of Region III of AEC Regulatory Operations Telephone: Mr. P. Johnson, 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br /> on January 6, 1975 Telegram Mr. James G. Keppler, 1545 hours0.0179 days <br />0.429 hours <br />0.00255 weeks <br />5.878725e-4 months <br /> on January 6, 1975

3) ReporL 50-237/1974-53, Inspection of Eergen-Iacerson 5 hock Suppressors Report Number: 50-249/1975-1 Report Date: January 16, 1975 Occurrence Date: January 4, 1975 Facility: Dresden Nuclear Power Station, Morris, Illinois IDENTIFICATION OF GCCURRENCE When Unit 3 was shutdown en January 3,1975, an inspection' was made of all thirty-five s nibbers in the drywell. The, inopoetion of the Eergen Paterson chock supprescorn on January 4, 1975, revealed that cicht enubbers were low on oil with two of than considered inoperacle. This conditicn could have prevented the performance of the intended cafety Ibnction of an engineered safety feature system.

CONDITIONS PRIOR TO OCCURRENCE

. Unit 3 was in the shutdown mode at the time of the inspection. The last inspection of the drywell snubbers was made about 105 days prior to this inspection.

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0 DESCRIIPION OF dC URRE2:CE -

The inoperable snubbers were found during a routine inspection during unit shutdown. The results of the inspections on the eight low snubbers are given in the following table.

Snubbers Found With Low Levels Snubber Piston Rod. Fluid Level Snubber I.D. No. Extension Position Location 1 2 5" 3 5" (low) B Recirculation Pump 14 2 5" 3 5" (low) A Recire Pump Discharge Line 19 3.o" 4.o'" (low) Recire. Header 22 3.0" 6.0" (inoperable) HPCI Line 25 3 5" 6.o" (inoperable) Feedwater Line 26 i.0" 2.0" (low) Feedwater Line 34 2 5" 3 5" (low) 3A Target Rock Safety Valve 35 2.75" 4.25" (low) 3A Target Rock Safety Valvc Note: The seal material for the above eight snubbers is othylene propylene.

DESIGNATION OF APPARETT CAUSE OF OCCURRD;CE (Equipment Failure)

The tuo inoperable snubbers were removed from the drywell and disassembled for a more thorough e:: amination. This inspection revealed that the 0-ring's were pinched, the seals showed slight deterioration and the cylinder was scratched. No singular cause can be assigned as modo of failure, rather all of the aforemontioned problems contributed to the loss of oil frca the snubbers.

ANALYSIS OF OCCURRE!CE ,

l . . The tuo-ihoperable snubbers did not threaten the health and. safety,of the public. The emergency core cooling systems and prir.ary containment were j - available to provide adequate core cooling and containment within the i

drywell had a pipe rupture occurred.

CORIETIVE ACTION The two inoperable snubbers were replaced with rebuilt snubbers containing ethylene propylene seal material and oil was added to the other six snubbers c~ .

Mr. James G. Keppler -3.- January 16, 1975 4 * -^,

. Q\ (v3 theneEtday. ld inspection was made of the eight snubbers to verify proper operation prior to start up.

FAILURE DATA Most of snubber failures in the past were related to the usage of polyurethane seal material. This occurrence has no singular cause, but is attributable to the several minor problems which allowed an excessive oil leakage condition to exist during the 105 day operating period between inspections.

On January 16, 1975, Mr. R. Knop of AEC Region III was notified that this Abnormal Occurrence report would be submitted 12 days after the date of occurrence due to extended review of the problem.

% r &4 4%. B. Stephenson Superintendent

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