ML20086S306

AO-S1-74-16:on 741220,radiation Monitor Alarm Accurred on RM-SW-107 Which Monitors Svc Water Leaving Component Cooling Hxs.Caused by Pin Holes in Component Cooling HX 1-CC-E-1C Tubes.Hx Isolated from Svc Water Sys

ML20086S306
Person / Time
Site:	Surry
Issue date:	01/23/1975
From:	Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AO-S1-74-16, NUDOCS 8403010492
Download: ML20086S306 (6)

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VzuotNIA ELECTRIC AND Powan COMPANY Racaxoxn.VraoxxtA 20261 g

January 23, 1975 4 gg+.at0 e gu 301975- ,

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Mr. Norman C. Moseley, Director Se " '

-) C Directorate of Regulatory Operations P0&M United States Atomic Energy Commission ,

Region II - Suite 818 Docket No. 50-280 230 Peachtree Street, Northwest License No. DPR-32 >

Atlanta, Georgia 30303 1

Dear Mr. Moseley:

N Pursuant to Surry Power Station Technical Specification 6.6.B.1, the Virginia Elect.ric and Power Company hereby submits forty (40) copies f, of Abnormal Occurrence Report No. A0-SI-74-16. e The substance of this report has been reviewed by the Station Nuclear Safety and Operating Committee and will be placed on the agenda for the next L meeting of the System Nuclear Safety and Operating Committee.

Ver; t=ly ycurc,

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C. M. Stallings Vice President-Power Supply and Production Operations Enclosures 40 copies of A0-SI-74-16 l(

f cc: Mr. K. R. Goller, Assistant Director '] ,

for Operating Reactors '1 Mr. Bryce P. Scholfield -

Supervisor, Radiological Health Section Department of Health lj 3

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a B403010492 750123 PDR ADOCK 05000280 S PDR 1>

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% ,I ABNORMAL OCCURRENCE REPORT REPORT NO. A0-SI-74-16 UNPIRINED RELEASE OF LOW LEVEL RADIOACTIVE COMPONENT COOLING WATER TO JA'1ES RIVER DECEMBER 23, 1974 DOCKET NO. 50-280 LICENSC NO. DPR-32 SURRY POWER STATION VIRGINIA ELECTRIC AND POWER COMPANY h

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(us I. INTRODUCTION In accordance with Technical Specification 6.6.B.1 for Surry 7ower Station, Operating License Number DPR-32, this report describes an abnormal occurrence which occurred on December 20, 1974. The Directorate of Regulatory Operations, Region II, was notified on December 20, 1974.

The occurrence reported herein is classified as an abnormal occurrence pursuant to Technical Specification 1.0.'.3 which states that "An abnormal occurrence is defined as: any uncontrolled or unplanned release of radio-activity from the site."

The occurrence described herein resulted in the release of radioactive component cooling water to the James River.

II.

SUMMARY

OF OCCURRENCE On December 20, 1974 at about 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> with both units at cold shutdown, a radiation monitor alarm occurred on RM-SW-107. This device monitors the service water leaving the component cooling heat exchangers.

Component cooling heat exchanger 1-CC-E-lC was immediately isolated from both the service water and component cooling water systems. The shell pressure of 1-CC-E-lC was observed to decrease to less than component cooling system pressure thus indicating a leak. It is estimated that this leak resulted in the release of 349 gallons of low level radioactive com-ponent cooling water to the James River.

III. ANALYSIS OF OCCURRENCE Subsequent to the isolation of 1-CC-E-1C from the service water system, the strip chart for RM-SW-107 was analyzed. An upward trend 1

o o-in service water radic'ctivity was indicated for a period of 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> and 15 minutes prior to the isolation of 1-CC-E-1C. A downward trend in service water radioactivity started af ter 1-CC-E-1C was isolated.

1-CC-E-1C was opened so that the actual tube leakage could be observed. When the shell side of 1-CC-E-1C was pressurized to component cooling system pressure, pin-hole leaks were observed in two tubes. This leakage was measured to be .376 and .139 gallons per minute, respectively.

Thus the actual total leak rate from 1-CC-E-1C was .515 gpm. As a con-servative estimate, this rate of leakage existed for 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> and 15-minutes, and resulted in the release of.349 gallons of low level radio-active component cooling water to the James River via the . service water system.

IV. CORRECTIVE ACTION TO PREVENT RECURRENCE The initial corrective action taken was to isolate 1-CC-E-1C from the service water system. In order to prevent recurrence the following corrective action has been implemented:

1. A tube which failed previously in 1-CC-E-1C has been extracted and cut into sections for analysis. Pre-liminary results of the ~ analysis indicate that the mode

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of failure was mechanical in nature and not related to corrosion phenomena.

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2. Procedures have been instituted which prohibit the

. use of! component cooling system pump and heat Jex :

changer combinations which could stress heat. exchanger tubes and cause further failures.

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3. RM-SW-107 is being monitored and readings logged every two hours to ensure that trends are detected in a timely manner.

4. Two tubes from 1-CC-E-lC have been removed for further inspection.

V. ANALYSIS AND EVALUATION OF SAFETY IMPLICATIONS OF Tile OCCURRENCE The concentration of the radionuclides present in the component cooling water during the leak were as follows: Cesium 134-4.81 x 10-5 pCi/ml, Cesium 137-1.94 x 10-4 pCi/ml. During the leak, the percentages of MPC released for each radionuclide are as follows: Cs l34 .473 x 10-3%,

Csl37 .85 x 10-3%. This represents a prorated aggregate of 1.32 x 10-3%

FTC.

The above figures are based on the following additional assumptions:

no radioactive decay of the radionuclides of interest, and three circulating water pumps running for the duration of the release.

Therefore, it can be concluded that no 10 CFR 20 limita were exceeded as a result of this unplanned release. The limit specified in Technical Specification 3.11.A.2 has not been exceeded for the present calendar quarter.

V1. CONCLUSIONS The licensee concludes that:

1. The unplanned release was due to tube failure and subsequent leakage in component cooling heat ex-l changer 1-CC-E-IC.

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2. An insignificant amount of radioactivity was released to the environment and all radionuclide concentrations were within 10 CFR 20 limits.

3. The occurrence described herein did not af fect the safe operation of the station.

4. The occurrence described herein did not affect the health and safety of the general public.

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