ML20086S412

SR-S1-74-04:on 740904,sampling of Ventilation Vent Activity Revealed I-131 Activity of 5.8% of Tech Spec Limit.Caused by High Activity of Steam Generator a Blowdown Vent.Primary to Secondary Tube Leak Repaired

ML20086S412
Person / Time
Site:	Surry
Issue date:	01/10/1975
From:	Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Moseley C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20086S415	List: ML20086S412 ML20086S417
References
SR-S1-74-04, SR-S1-74-4, NUDOCS 8403010554
Download: ML20086S412 (4)

Text

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VIRGINI A E x.1:cT1 tic ANi> Po wn:it Co> 1*A N Y Hicar n owi>. Vi scor n:A cocon 'D

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/ ii\7 Mr. Norman C. Moseley, Director Serial No. 398 Directorate of Regulatory Operations P0&M/JTB:c1w United States Atomic Energy Commission Region II - Suite 818 Docket No. 50-280 230 Peachtree Street, Northwest License No. DPR-32 Atlanta, Coorgia 30303

Dear Mr. Moseley:

The Virginia Electric and Power Company hereby submits forty (40) copies of Special Report No. SR-SI-74-04.

The substance of this report has been reviewed by the Station N,uclear Safety and Operating Committee and will be placed on the agenda for the next meeting of the System Nuclear Safety and Operating Committee.

Very truly yaurs,

. .% d$ ace p C. M. Stallings Vice President-Power Supply and Production Operations Enclosure cc: Mr. K. R. Coller (39 copies) s S

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SPECIAL REPORT SR-SI-74-04 VENTILATION VENT CASEOUS AND PARTICULATE ACTIVITY DOCKET NO. 50-280 LICENSE NO. DPR-32 CCTOBER 10, 1974:

SURRY POWER STATION -

VIRGINIA ELECTRIC AND POWER COMPANY P

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I. INTRODUCTION 4

In accordance with Technical Specification 6.6.B.3 for Surry Power Station, this report describes the release of gaseous and airborne

< particulate releases in excess of 4 per cent of the Technical Specification limits established by Technical Specification 3.11.B.1.

II.

SUMMARY

OF OCCURRENCE On September 4, 1974, routine sampling of the ventilation vent

activity revealed an Iodine-131 activity of 5.8 per cent of the Technical Specification limit. An investigation to determine the source was initiated.

f Several minor valve leaks were found and repaired. However, Iodine-131 activity continued to rise, roughly in proportion to the activity in Unit No. 1 Steam Generator "A". Due to the absence of any known leakage of primary coolant into the auxiliary building and due to'the correlation between activity in Steam Generator "A" and ventilation vent activity,_it-was determined that airborne particulate in the blowdown was-the source of the ventilation vent activity.

On September 18, 1974, ventilation vent 8-y activity exceeded 4 per cent of the Technical Speciffcation limit. I-131 and particulate activity _

continued to increase with B-y activity reaching a peak of 9 per cent' of the Technical Specification limit on September 20', 1974 and I-131. activity . -

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! reaching a peak of 22 per cent of the Technical Specification limit cut September 27, 1974.

i Unit No. I was-shutdownton September 29, 1974 and returned to service.

on Saptember 30, 1974 with "A" loop isolated. Following conversion to.two loop operation ventilation vent I-131 -and By particulate activity decreased rapidly. On October 1,~1974, ventilation vent Sy activity was.3.0 per

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( cent of the Technical Specification limit and I-131 activity.was 6.5 per cent of the limit.

4 III. ANALYSIS AND EVALUATION OF SAFETY IMPLICATIONS OF THE OCCURRENCE The ventilation vent particulate and I-131 activity was caused by the high activity of the Unit No. 1 Steam Generator "A" blowdown vent.

The high activity.of Steam Generator "A" was due to primary to secondary tube leakage.

Two loop operation reduced the ventilation vent I-131 and By activity to 6.5 and 3.0 per cent, respectively, of. the Technical Specification limits (October 1, 1974).

The primary to secondary tube leak in Unit No. I steam generator "A" 4

has been repaired.

8 The releases described herein were well below the limits established by 10 CFR 20; therefore, there were no safety implications of the occurrence, l

J IV. CONCLUSION The ventilation vent particulate and I-131 activity was caused by the high activity of the Unit No. I steam generator "A" blowdown ~ vent.

The primary to secondary tube leak has been repaired.

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