ML20086D183

Deficiency Rept Re Failure of Valves Important to Safety to Meet Min Wall Thickness Requirements.Valve Verification Program Underway.Of 97 Valves tested,37 Set Aside for Further Testing.Results of Tests Forthcoming

ML20086D183
Person / Time
Site:	Diablo Canyon, 05000000
Issue date:	08/21/1973
From:	Searls F PACIFIC GAS & ELECTRIC CO.
To:	Knuth D US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086D171	List: ML20086D172 ML20086D183 ML20086D192
References
NUDOCS 8311300406
Download: ML20086D183 (2)

Text

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_ O PACIFIC GAS AND E I.aE C T R,I C C O1VIPANY l l

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U. S. Atomic Energy Commission 0*lin'!l."J'.

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Attention: Mr. D. F. Knuth, Director **';, .;*c,*.";...

Directorate of Regulatory Operatior}

Re: Dockets 0-275 50-323 Gentlemen:

In your letter dated June 20, 1972, you requested a verifi-cation, through manufacturing records and other suitable means, that valves important to nuclear safety installed or to be installed at Diablo Canyon meet the minimum wall thickness requirements of the specified codes or standards.

As outlined in our letter dated July 20, 1972, we have been pursuing a verification program at the plant site using ultrasonic methods. This program involves approximately 230 valves one inch and larger in size within the reactor coolant pressure boundary. At pres-ent writing, 97 valves have been tested; 75 for Unit 1 and 22 for Unit 2.

For each valve in the test program, Westinghouse has provided a nominal design wall thickness. In the testing program the wall thick-ness of each valve is measured and recorded at a number of locations.

Valves in which all measurements exceed the nominal wall thickness are accepted. Valves in which one or more measurements fall below the nominal wall thickness are tagged and set aside pending engineering analysis. At the present stage of our investigation 37 of the 97 valves measured have been placed in the latter category. A tabulation of the results of the measurement program is attached to this letter.

The testing is being performed in accordance with procedures i prepared and approved by PGandE. Results of the tests are being evalu- '

ated at our request by Westinghouse Electric Corporation in consultation I

with the various valve manufacturers..

l 8311300406 740802 Very truly yours, i PDR ADOCK 05000275 A PDR f

Attachment .

CC: Mr. R. H. Engelken, Director '

• l Directorate of Regulatory Operations  !

Region V , e 'yQ 13 p. .

3 G789

, 4' WESTINGHOUSE SUBJECT VALVE IDENTIFICATION QUANTITY TO FURTHER SIZE NUMBER TYPE BODY TESTED ACCEPTABLE EVALbATION 10" 10C48Z Check Cast 16 3 13 8" 8C48Z Check Cast 4 2 2 g 6" 6C58 Check Forged 15 15 0 Gate Forged 4 0 4 4" 4G58 Check Forged 20 2 18 3" 3C58 3" 3G58 Gate Forged 5 5 0 2" 2T58 Globe Forged 10 10 0 2C58 Check Forged 19 19 0 2"

Gate Forged 2 2 0 14" 14GM48SEZ 3" 3IA58RGP Globe Cast 1 1 0 2IA58RE Globe Cast 1 1 0 0

2" 97 62 37

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