ML20084S735

AO 50-265/75-20:on 750623,reactor Bldg to Suppression Chamber Vacuum Breaker Found Inoperable.Caused by Fouled Swing Gate Bushings.Packing Replaced & Teflon Bushing Cleaned

ML20084S735
Person / Time
Site:	Quad Cities
Issue date:	07/02/1975
From:	Kalivianakis N COMMONWEALTH EDISON CO.
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20084S739	List: ML20084S735 ML20084S741
References
AO-50-265-75-20, NJK-75-344, NUDOCS 8306170199
Download: ML20084S735 (3)

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July 2, 1975 Director of Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Reference:

Quad-Ci ties Nuclear Power Station Docket No. 50-265, DPR-30, Uni t 2 Appendix A, Sections 1.0.A.5, 3.7.A.3.a. 3 7.A.3.b, 6.6.B.I.a Enclosed please find Abnormal Occurren~ce Report No. SC-265/75-20 for Quad-Cities Nuclear Power Station. This occurrcnce was previously reported to Region lil, Directorate of Regulatory Operations by telephone on June 24, 1975 and to you and Region 111, Di rectorate of Regulatory Operations by telecopy on June 24, 1975 This report is submitted to you in accordance wi th the requi rements of Tech-nical Speci fication 6.6.B. I .a.

Very truly yours, COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION l

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. J. Kalivianakis Station Superintendent NJK/HGL/lk cc: Region li t , Di rectorate of Regulatory Operations J. S. Abel 8306170199 750702 FDR ADOCK 0500026 S PDR c

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REPORT NUMBER: A0 50-265/75-20 ,

REPORT DATE: June 30, 1975 OCCURRENCE DATE: June 23, 1975 FACI LI TY: Quad-Cities Nuclear Pover Station Cordova, Illinois 61242

' IDENTIFICATION OF OCCURRENCE:

The Unit 2 reactor building to suppression chamber vacuum breaker (2-1601-31 A) was inoperable.

CONDITIONS PRIOR TO OCCURRENCE:

Unit 2 was operating at 2023 MWt and 607 MWe, The occurrence was encountered during routine reactor building to suppression chamber vacuum breaker sur-veillance testing as prescribed in Technical Speci fication 4.7. A.3.a.

DESCRIPTION OF OCCURRENCE':

On June 23,1975, at 11:30 a.m. the quarterly surveillance testing of the reactor building to suppression chamber vacuum breaker 2-1601-31A was being performed as prescribed in Technical Speci fication 4.7. A.3.a. At this time it was discovered that the torque necessary to fully open the vacuum breaker valve exceeded the Quad-Cities surveillance procedure 43-7.1.5-2 limit

. of 50 ft. Ibs. Additional torque was applied to the vacuum breaker valve.

Movement was noted in the valve counterweight at a torque of between 85 and 90 ft. lbs. but the torque indicating test apparatus broke at this point. Further torque was required to fully open the valve. The 2-1601-31 A vacuum breaker was declared to be inoperable as defined by Quad-Lities surveillance procedure 43-7 1.5-2 because of excessive opening torque and the Shif t Engineer was notified of the situation. A Work Request was issued to repair vacuum breaker 2-1601-31A. To insure the integrety of the vacuum breaker function, the parallel 2-1601-31B vacuum breaker valve was operated. Although no test apparatus was available at this instant the torque needed t.o fully _open this valve was noticably less than .

that needed to open the 2-1601-31A valve.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

The apparent cause of this occurrence was equipment failure. The reactor

! building to torus vacuum breaker, 2-1601-31A, would not open due to fouled swing gate bushings.

ANALYSIS OF OCCURRENCE:

The effects of this occurrence were minimized due to the fact that the parallel vacuum breaker 2-1601-31B was functional at all times and valve 31A was repaired and retested in less than the seven days allowed by i

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o o A0 50-265/75-20 June 30, 1975 i

Technical Speci fications. It should also be noted that this occurrence was detected from a routine preventative surveiliance and not during an

actual required reactor scram function; therefore, there was no effect on public health and safety. '

CORRECTIVE ACTION:

The action taken to correct this abnormai occurrence was to replace the packing and clean the teflon bushing of the 2-1601-31 A vacuum breaker.

Once this was completed the check valve swung freely. Repai rs and re-testing were completed on June 27, 1975 In order to deter the recurrence of such equiprent failures, surveillance procedures were enlarged in Temporary Change No. 449 to include the following limitation:

"If the vacuum breaker, does not swing f ree to i ts closed posi tion, regardless of i ts opening torque valve, the vacuum breaker must be considered inoperable. Natify the Shif t Engineer, initiate a Work Request for repai rs, and refer, to Technical Speci fications section

.3 7.A.3."

4 l In this way fouling of the vacuum breaker can be acted on as soon as impair-ment of free movement of the valve is detected.

I FAILURE DATA:

1 This is the first failure of this type since the vacuum breakers were

! modi fied by Mod Number M-4-2-74-61 during the past Unit two refueling i

outage. Therefore, there are no safety implications based on cumulative experience.

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