ML20215C577

Part 21 Rept Re Small Leak in Unit B Cooling Water Header Lower Pipe in Right Bank of Emergency Diesel Generators. Affected Water Header Pipes Replaced W/Upgraded Matl & Unit a Water Header Pipes Visually Inspected for Leakage

ML20215C577
Person / Time
Site:	Beaver Valley
Issue date:	06/10/1987
From:	Garfinkel P STONE & WEBSTER, INC.
To:	Berlinger C Office of Nuclear Reactor Regulation
References
REF-PT21-87-113-000 PT21-87-113, PT21-87-113-000, NUDOCS 8706180174
Download: ML20215C577 (3)

Text

i STONE 8 WEBSTER ENGINEERING CORPORATION 245 SUMMER STREET, B O STO N. M ASS ACH U SETTS j ADDRESS ALL CORRESPONDENCE TO P.O. BOX 2325. BOSTON. M A 02107 W U, TELEX 94 0001 l

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} O' Mr. Carl Berlinger June 10, 1987 Generic Communications Branch Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555 NOTIFICATION OF DEFECT BEAVER VALLEY POWER STATION UNIT 2 DUQUESNE LIGHT COMPANY Stone & Webster Engineering Corporation (SWEC), pursuant to the provisions of 10CFR21, hereby provides notification of a " defect" concerning the Beaver Valley Power Station Unit 2, owned in part by Duquesne Light Company (DLC), and for which SWEC is providing both engineering and construction services.

In accordance with the reporting requirements of Section 21.21(b)(3), the following information is submitted:

i. Name and address of the individual informing the Commission: 1 l

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Mr. P. Garfinkel j Director of Engineering Stone & Webster Engineering Corporation P.O. Box 2325 Boston, MA 02107 ii. Identification of the facility, or the basic component supplied for such facility, which contains a defect:

Beaver Valley Power Station Unit 2 Emergency Diesel Generators lii. Identification of the firm constructing the facility or supplying the basic component which contains a defect:

Basic component supplied by Colt Industries iv. Nature of the defect and the safety hazard which could be created:

During preoperational (warranty) testing of the emergency diesel generators, a small leak appeared in the Unit "B" cooling water header lower pipe (2 inch Schedule 40) in the right bank.

Subsequently, during normal weekly field testing of Unit "B", g@

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r-2 a leak appeared in the left bank of the cooling water header lower pipe. It was noted that both pipe failures occurred in the coolant system's low spots and at the 6 o' clock location. Because similar through wall pitting was experienced at two low spots where water could be trapped, other water trap locations could be affected. Investigation of the possible causes of the corrosion found in the jacket and intercooler water piping of the emergency diesel generators concluded that the material corroded due to.

either microbiological 1y induced corrosion (MIC), or a reduction in the effective strength of the corrosion inhibitor used during shop testing and/or storage.

The emergency diesel generators serve as the primary electrical supply during accident conditions. Makeup water to the cooling water . system is provided. from the nonsafety-related demineralized water system. A safety-related low level alarm in the cooling water expansion tank annunciates locally and on the control board after the loss of approximately 33 gallons. This corresponds to the expected coolant leakage during a seven day period (FSAR Table 9.5-7). Any additional loss of inventory over a seven day period could reduce cooling system efficiency and cause EDG shutdown on cooling water high temperature. This represents a major reduction in the degree of protection provided to the public health and safety and could create a substantial safety hazard,

v. Date on which information of such defect was obtained:

June 10, 1987 >

vi. In the case of a basic component which contains a defect, the number and location of all such components in use at, supplied for or being supplied for facilities subject to the regulation:

Beaver Valley 2 is the only project for which SWEC has or had applicable engineering, design or procurement responsibility determined to have this defect.

i vii. Corrective action which has been taken; name of individual or organization responsible; and length of time taken to complete the action:

The affected water header pipes on Diesel Generator Unit B were replaced with upgraded material. The water header pipes on Unit A were visually inspected (externally) for leakage, and no leakage was found. Additionally, the water header pipes on Unit A were ultrasonically inspected to ensure adequate vall thickness and were determined to be within specified limits.

The following remedial actions for both diesels were recommended to DLC to preclude further corrosion.

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1. Drain and flush the entire coolant system.  !

2. Refill the entire system with demineralized water and a l concentration of hydrogen peroxide (H2 02 ) between 50 and I 100 ppm. j l

3. Run the units to assure that the solution is mixed and distributed thoroughly (all valves and thermostats open).

4. Monitor the system for H 202 to ar,sure the concentration is ,

between 50 and 100 ppm. Monitor hourly for at least five hours to assure the H 202 concentration has stabilized between 50 and 100 ppm. Thereafter, monitor every five hours 1 for a total exposure of 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />. Add H022 as required, l

5. After treatment, flush the system with at least two volume changes of sterile demineralized water, and refill with sterile demineralized water containing a manufacturer's approved corrosion inhibitor (preferably NALC0 39M) at the  :

recommended concentration and a biocide (glutaraldehyde) at a concentration of 50 to 100 ppm. The inhibitor, NALC0 39M, j used after treatment, will prevent corrosion from occurring when maintained at the proper concentration.

6. The integrity of the cooling water piping of both units will then be tested by a hydrotest of the system at 125 percent design pressure.

viii. Advice related to the defect that has been given to purchasers or licensees:

DLC was advised of the defect and the corrective action.

If you require any further information, please contact Mr. R. B. Bradbury at (617) 589-1291.  ;

f au P. Gar inkel Director of Engineering i