ML20086S913

AO-S2-74-05:on 740701,indications of Minor Primary to Secondary Steam Generator Tube Leak in Steam Generator B Found.Caused by Tube Failure Two Inches Above Top Tube Support.Tube Plugged

ML20086S913
Person / Time
Site:	Surry
Issue date:	07/19/1974
From:	Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AO-S2-74-05, AO-S2-74-5, NUDOCS 8403060024
Download: ML20086S913 (5)

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Ricarwoxo.VraoxxrA 20261 LTJ,, Q y-I July 19, 1974 p e -

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Mr. Norman C. Monaley, Director Serial No. 208 ,

Directorate of Regulatory Operatione PO&M/JTB:c1w United States Atomic Energy Commission Region II - Suite 818 Docket No. 50-281 230 Peachtree Street Northwest License No. DPR-37 Atlanta, Georgia 30303

Dear Mr. Moseley:

Pursuant to Surry Power Station Technical Specification 6.6.B.1 j the Virginia Electrie and Power Company hereby submits forty (40) copies of Abnorual Occurrence Report No. AO-32-74-05.

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

Very truly yours, Original Signed By STANLEY RAGONE f.VC.M.Stallings Vice President-Power Supply and Production Operations Enclosures 40 copies of A0-82-74-05 ces Mr. K. R. Coller, Assistant Director /

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• ABNORMAL OCCURRENCE REPORT REPORT NO. A0-S2-74-05 STEAM GENERATOR PRIMARY TO SECONDARY LEAKAGE JULY 8, 1974 DOCKET No. 50-281 LICENSE NO. DPR-37 SURRY POWER STATION VIRGINIA ELECTRIC AND POWER COMPANY r

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• INTRODUCTION O , ,

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In accordance with Technical Specification 6.6.B.1 for Surry Power Station, Operating License Number DPR-37, this report describes an abnormal i

occurrence which occurred on July 1, 1974. The Directorace of Regulatory Operations, Region II, was notified on July 2, 1974.

1 Rue occurrence reported herein is classified as an abnormal occurrence pursuant to Technical Specification 1.0.I.4 which states that "An abnormal occurrence is defined as: Any abnormal degradation of one of the several boundaries which are designed to contain radioactive materials resulting from the fission process."

The occurrence described herein involved a primary to secondary leak in the "B" steam generator, resulting in a degradation of the reactor coolant system boundary. The steam generator is a Series-51 generator manufactured by Westinghouse Electric Corporation.

II.

SUMMARY

OF OCCURRENCE Indications of a minor primary to secondary steam generator-(S/G) tube leak in "B" steam generator during normal operations . precipitated an inspection of subject S/G while the unit was at cold shutdown (CSD) for an inspection of the main steam non-return valves. The inspection on July 1,_

1974 revealed an actual tube leak. The unit was at CSD with reactor coola'nt average temperature at 120 de'rees g F and primary pressure at 4'00 psia.

III. ANALYSIS OF OCCURRENCE A recent leak in the liquid waste reboiler caused high activity in the auxiliary steam system which masked the activity due to the-S/G tube leak.

However, as the activity at time of shutdown was. higher.in "B" S/G than w

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V the other S/G's and contained several tracer isotopes of fission products, "B" S/G was inspected. It was found that a tube had failed at a point approximately two (2) inches above the top tube support on the hot leg side of the tube, row 43, column 62.

During the time the unit was in operation before the tube leak was discovered, the I-131 activity in "B" did not exceed 8.2 x 10-3 curies and the total primary system leak rate was less than one (1) gpm.

IV. CORRECTIVE ACTION TO PREVENT RECURRENCE The leaking tube was plugged. Five other tubes showing degradation were plugged as a precautionary measure.

This is the first steam generator tube leak experienced on either of the units at Surry Power Station. At the present time, more precise chemistry control is being maintained in the seconcary system, as well as a new sodium to phosphate ratio recommended by ,

Westinghouse.

V. ANALYSIS AND EVALUATION OF SAFETY IMPLICATIONS OF THE OCCURRENCE The unit is able to operate safely with minor steam generator leakage. ihe event described herein did not result in the violation of a limiting condition of operation as delineated in the Technical Specifications, nor have the 1Laits been approached. Therefore, there are no safety implications associated with this event.

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O O VI. CONCLUSIONS The licensee concludes that:

1. The degradation of the reactor coolant system boundary was caused by a primary to secondary leak in the "B" steam generator.

2. The occurrence reported herein did not affect the safe operation of the station.

3. The occurrence described herein did not adversely affect the health or safety of the general public.

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