ML19344F238

Part 21 Rept Re Potential Nonconservatism in Indicated Feedwater Flow Due to Fouling of Feedwater Venturi. Detailed Engineering Evaluation Is Being Performed

ML19344F238
Person / Time
Site:	North Anna
Issue date:	08/15/1980
From:	Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
References
REF-PT21-80-275-000 712, NUDOCS 8009120702
Download: ML19344F238 (3)

Text

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R xcnwoNo, VIRGINIA 20261 August 15, 1980 To -A 75% o o Mr. James P. O'Reilly, Director Serial No. 712 Office of Inspection and Enforcement N0/FHT:smv U. S. Nuclear Regulatory Commission Docket No. 50-338 Region II License No. NPF-4 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

On August 9, 1980, a report was made under the provisions of 10CFR21 concerning a potential nonconservatism in the indicated feedvater flow due to fouling of the feedwater venturi.

In accordance with the reportiar requirements of 10CFR21, the following infor-mation is submitted:

A. Name and address of reporting individual:

Mr. E. A. Baun , Executive Ma nager Licensing and Quality Assurance Virginia Elcetric and Power Company P. O. Box 26666 Richmond, Virginia 23261 B. Facility, activity and/or component affected:

North Anna Power Station Unit 1 Feedwater flow venturf input to reactor protection logic circuits.

C. Name of firm constructing the facilr.ty or supplying the component, activity or service:

Westinghouse Electric Corporation NSSS Vendor D. Description of defect, deficiency or failure to comply:

A review of Unit I calorimetric data revealed that indicated feed-water flow was greater than indicated steam flow. It was postulated that this was caused by fouling in the feedwater venturi. Westing-house was asked to confirm that the indicated feedwater flow was in error.

On August 7,1980, notice was received from Westinghouse, by letter VPU(JLV)-7, that this feedwater flow could be indicating higher than actual flow by 3% to 5% due to venturi fouling. Since the feedwater

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flow signal feeds the solid state protection system, a nonconserva-tive error in the setpoint of steam flow greater than feedwater may be produced.

E. Date of' determination of reportability:

August 11, 1980 t

F. Similar components, activities or services:

North Anna Unit 2 Surry Units 1 and 2 G. Corrective action which has been, is being, or will be taken, the individual responsible, and the length of time to complete the action.

As a precautionary measure, a setpoint change to reduce the steam flow greater than feed flow setpoint by 5% was approved and imple-mented on August 7,1980, while a detailed engineering evaluation was being performed to determine if the steam flow 'eed flow setpoint was nonconservative.

On August 8, 1980, the original setpoint was confirmed to be noncon-

, servative by approximately 4% contrary to the limits in T.S. Table 2.2-1 and reportable by T.S. 6.9.1.8.b. The precautionary setpoint adjustment made on August 7,1980, is sufficient to compensate for this error. Feedwater fouling will be monitored by comparison to steam flow to ensure that the setpoint remains conservative. Addi-tional adjustments to the setpoint will be made if required.

H. Other information:

Preliminary analyses indicate that the venturi fouling may be due to feedwater system corrosion products plating out on the venturi surface.

Although Surry Units 1 and 2 use similar venturis in their feedvater lines, inspections and operational monitoring have not indicato a problem with fouling at these two units.

If you have any questions or require additional information, please contact this office.

Very truly yours, B. R. Sylvia Manager - Nuclear Operations and Maintenance FHT/sav:ST2 cc: Director, Office of Inspection and Enforcement (3)

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