ML20086S701

Suppl 1 to USRE-S1-76-01:751204,no Air Flow Indicated from Local Flow Indicator on Containment Gaseous & Particulate Monitor Cabinet.Caused by Failed Bearing on Vacuum Pump. Bearing Replaced & Pump Tested Satisfactorily

ML20086S701
Person / Time
Site:	Surry
Issue date:	05/07/1976
From:	Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20086S707	List: ML20086S701 ML20086S709
References
USRE-S1-76-01, USRE-S1-76-1, NUDOCS 8403050059
Download: ML20086S701 (5)

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.O VimonxxA Er.ucraic Axn Powr.n CourAxy Riouxoxo.V mointA 20261

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May 7, 1976 &

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u.s...q m y y ?. "7 ;s y ,e Mr. Norman C. Moseley, Director Seria[N -

Office cf Inspection and Enforecment PO8H/ALHijlf i United States Nuclear Regulatory Commission

Region II - Suite 818 Docket Nos. 50-230 230 Peachtree Street, Northwest 50-281 j Atlanta, Georgia 30303 License Nos. DPR-32 i DPR-37

Dear Mr. Moseley:

). Pursuant to Surry Power Station Technical Specification 6.6.2, the

! Virginia Elcetric and Power Company hereby submits a copy of The Supplemental Report To USRE-S1-76-01.

The substance of this report has been revicwed by the Station Nucicar Safety and Operating Committee and will be placed on the agenda for the next Eceting of the System Nuclear Safety and Operating Committee.

Very truly yours,

. . A[N '

C. M. Stallings Vice President-Power Supply and Production Operat. ions i '

, Enclosure cc: Mr. Robert W. Reid, Chief (40)

. Operating Reactors Branch 4 4

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4679 8403050059 760507 PDR ADOCK 05000200 S PDR I

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SUPPLFJfENTAL REPORT

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USRE-St-76-01 INOPERABILITY OF UNIT NO. 1 AND UNIT NO. 2

, CONTAINMENT CASEOUS AND PARTICULATE MONITmS APRIL 28,1976 DOCKET NOS. 50 280 AND 50-281 LI_ CENSE N_OS. DPR-3 2 AND _ DPR-3 7 i

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SURRY POWER STATION VIRGINIA ELECTRIC AND POWER COMPANY .

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l I. INTRODUCTION This report is submitted to provide supplemental information to USRE-S1-76-01, which described an occurrence involving the inoperability of contain-ment gaseous and particulate monitors of Unit Nos. 1 and 2. This report will be concerned with the duration of the inoperable condition and with actions taken to prevent recurrence.

II.

SUMMARY

OF OCCt'RRENCE At the time of the occurrence, Unit No. I was at refueling shutdown and Unit No. 2 was operating at 100 percent power. On December 4, 1975, at approximately 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br />, a member of the operations staff noted that there was no air flow indicating from the local flow indicator on the Unit No. 2 con-tainment gascous and particulate monitor cabinct. The flow indicator on Unit No. 1 was then checked and found to be reading zero. While the vacuum pump control switch on each unit was checked "on", neither unit indicated any air flow.

Investigation revealed a failed bearing on the Unit No. 1 vacuum pump.

The bearing was replaced and the pump tested satisfactorily, and was returned

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to service. The loss of flow through the Unit No. 2 monitors was due to a clogged inline charcoal filter. Following replacement of the filter element, the flow rate through the monitors returned to the design level of 10 cfm.

III. DURATION OF INOPERABILITY ,

A review of station records has been made to determine the duration of the inoperability of the containment gascous and particulate monitors on ~

Unit Nos. 1 and 2.

A maintenance request for Unit No. 1 issued November 17, 1975 indicates that the loss of flow was originally noted on that date. However, the operator

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L O I did not designate the maintenance request as " urgent" in that the unit was shut-down and refueling was completed. The Unit No.1 vacuun pump was repaired on December 4, 1975. Thc, Unit No.1 monitors were inoperable for 18 days.

A maintenance request for Unit No. 2, noting zero monitor flow, was l

originally issued on November 25, 1975. The problem was originally believed I

to be due to a vacuum pump failure. However, on January 6, 1976, the loss of 4 flow was determined to be the result of a clogged inline charcoal filter. The filter was replaced at that time and monitor flow returned to normal. The Unit No. 2 monitors were inoperable for 42 days.

During the period of time that the Unit No. 2 monitors were inopera-l bic, the process vent system particulate and gaseous monitors served as an al-l ternate method of reactor coolant Icak detection via the containment vacuum I

pumps. The discharge of the vaquum pumps leaves the site via the process vent s'ystem. Therefore, any reactor coolant leckage would have been detected by This indication in conjunc-the process vent particulate and gaseous monitors.

tion with other indicators (changes in reactor coolant inventory, high sump levels, etc.) provide evidence of reactor coolant leakage.

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IV. ACTIONS TAKEN TO PREVENT RECURRENCE l Prior to this occurrence, the only indication of a loss of flow through these monitors has been the flow fault alarm. This alarm system failed 4

to indicate the loss of flow on the Unit No. 2 monitors.

In order to provide a redundant indication of loss of flow Periodic Test No. 26.1, Radiation Monitoring Equipment Check', has been revised to in-clude a recording of the containment gaseous and particulate monitor flow rates.-

! This will provide a daily verification of monitor flow via the local flow indi-Cator.

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'V. CONCLUSION The duration of inoperability of the containment gaseous and.particu-late monitors on Unit Nos. 1 and 2 was 18 and 42 days, respectively.

The periodic check of radiation monitors has been revised to provide redundant checks of the flow rates through these monitors.

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