ML19276F150

Forwards Non-Routine Rept 50-313/79-01

ML19276F150
Person / Time
Site:	Arkansas Nuclear
Issue date:	03/16/1979
From:	Reuter D ARKANSAS POWER & LIGHT CO.
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19276F151	List: ML19276F150 ML19276F156
References
1-039-12, 1-39-12, NUDOCS 7903270412
Download: ML19276F150 (1)

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H E L PI N G BUILO A n n~ A N S A S A RK ANS AS POWER & LIGHT COMPANY P Q DOX 551

• LITTLE AOOK. AAKANSAS 72203*(501)371-4191 March 16, 1979 OONALO A. AUETER DIRECTOR TECHN: CAL AND EN' 10NMENTAL SERVICES 1-039-12 Mr. K. V. Seyfrit, Director Office of Inspection 6 Enforcement U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011

Subject:

Arkansas Nuclear One-Unit 1 Docket No. 50-313 License No. NPR-51 Non-Routine Report No. 50-313/79-1 (File: 0520)

Gentlemen:

In accordance with Arkansas Nuclear One - Unit 1, Appendix B Technical Specification 5.6.2(b), we have attached the subject non-routine report concerning tbc failure to maintain the maximum differential temperature across the condenser below 15'F as required by Tech Spec 2.1.1(a).

Very truly yours,

/ s.; ,.m - ' '

/ a&l /

,i

?- -

- Donald A. Rueter DAR:REI;1g Attachment cc: Mr. Norman M. Haller, Director Office of Management and Program Analysis U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. John G. Davis, Acting Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 7903270hp TAX P AY 8 N G. IN V E S T O A OW N E O $ MEMD E R MIDDLE SOUT H UTILITIE S SY STEM

Non-Routine Report No. 50-313/79-1

8. Designation of Apparent Cause of Occurrence:

Design Procedure Manufacture _ Unusual Service Condition Includ-ing Environmental X Installation /

Construction Component Failure (See Failure Data)

Operator X Other (specify)

The abnormally high temperature differential across the condenser was caused by an excessive impingement of Threadfin Shad fish on the circulating water intake screens.

Carryover from the screens apparently caused some plugging I of the condenser circulating water inlet tube sheets, re-stricting the flow of cooling water. The lower flow rate resulted in a higher temperature rise. The excessive temperature rise beginning on 2/9/79 was not discovered during the normal daily review of operating conditions.

9. Analysis of Occurrence:

There was no thermal stress to the aquatic ecosystem as the temperature rate of increase was slow, the maximum discharge temperature was less than 52*F, and the tempera-ture differential was only exceeded by 0.45*F. The higher than normal temperature differential caused no operating difficulties.

10. Corrective Action:

The condenser inlet water box isolation valves are being cycled, as necessary, to allow the debris to wash off the condenser circulating water inlet tube sheets. This improves the flow rate. Monitoring the condenser ,

differential temperature has been improved by displaying the condenser differential and outlet temperatures,on a plant computer trend recorder.

11. Failure Data:

There have been no similar occurrences.