ML19276G915

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Suppl 1 to Significant Deficiency 369-370/79-01 on 790413: Pressurizer Power Relief Valve Plug Experienced Binding in Bonnet Recess Area.Caused by Bonnet Deformation.Valve Operator Design Is Being Modified
ML19276G915
Person / Time
Site: McGuire, Mcguire  Duke Energy icon.png
Issue date: 08/15/1979
From: Parker W
DUKE POWER CO.
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 7908280608
Download: ML19276G915 (1)


Text

DUKE power COMPANY Powra Bettarwo 422 SocTn Cucacu Srazzi, CHAHLOTTz, N. C. 28342

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August 15, 1979

?t6t a=omt. as ta 704 S'ta= Paoovetica 3 7 3- 4 0 e 3 Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 ..a

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Re: McGuire Nuclear Station -. -3 Units 1 and 2 E 'O Docket Nos. 50-369 and 50-370 -

SD 369-370/79-01, Supplement 1  ;

Dear Mr. O'Reilly:

c My letter of April 13, 1979 transmitted Significant Deficiency SD 369-370/79-01 which described a problem with the pressurizer power operated relief valves. ,

This report also identified action necessary to correct the deficiency. Subse- -

quent evaluation of the problem has resulted in additional corrective measures to assure proper valve operation. The purpose of this letter is to supplement the original report.

The basic problem identified in the original report was valve plug binding in the bonnet recess area due to bonnet deformation under combined thermal and operating stress conditions. In addition to the corrective actions identified in the original report, the valve operator design is being modified to provide additional spring seating force in the event the air supply to the operator is interrupted. Also, to reduce the thermal transients on the valse, a drain has been added to the piping loop seal upstream of the valve, effectively removing the loop seal.

The schedule for modification and testing of the valves is as outlined in the original deficiency report.

Ver truly yourg,

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William O. Parker, .

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