ML20086H390

Responds to 720622 Request for Verification of Wall Thickness for RCPB Valves.Program to Verify 56 Valves Will Be Proposed within 10 Days

ML20086H390
Person / Time
Site:	Vermont Yankee
Issue date:	07/21/1972
From:	Minnick L VERMONT YANKEE NUCLEAR POWER CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086H382	List: ML20086H384 ML20086H390
References
NUDOCS 8401170095
Download: ML20086H390 (2)

Text

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'4 O o VERMONT Y ANKEE NUCLEAR POWER CORPORATION SEVENTY SCVCN OROVC STRCCT Rurimo, Vennosr osvoi REPLY TO:

ENGINEERING OFFICE July 21, 1972 TURNPlKE ROAD WESTDORO. M ASS ACHUSETTS 01581 TELEPHONE 617 366 9011 Mr. James P. O'Reilly, Director Division of Compliance, Region 1 United States Atomic Energy Commission 970 Broad Street Newark, New Jersey 07102 USAEC letter dated June 22, 1972, Docket No. 50-271

Dear Sir:

Your letter requests Vermont Yankee to provide verification that valves within the reactor coolant pressure boundary meet the minimum wall thickness requirements of specified codes and stand-ards, or, in the event that verification is not available, to ad-vise you of our plans and schedules for demonstrating by suitable means that such valves are acceptable with respect to wall thick-ness.

As you are aware the codes and standards in effect at the time valves for this plant were purchased and installed did not require Standard documentation of specific wall thickness measurements.

practice was for the valve manufacturer to check for acceptable wallTh thickness on each valve.

except as general statements that the check was satisfactorily com-pleted.

A review of the piping systems at Vermont Yankee indicates that there are sight-two valves, 1-1/2 inch and larger, in the reactorUltrasonic ve coolant pressure boundary.

ness exists for fourteen of these valves and this documentation is available at the plant for review by your inspector.

We do not propose to attempt physical verification of the wall thickness for valves two inches and smaller because loss of coolant accident analyses have shown that a rupture of this sire would not re-sult in damage to the cora and, therefore, we do not consider these"'hus, there remain

( smaller valves to be significant to nuclear safety.e nominal size of two incbes for fifty-six valves above th.

cation has not been confirmed at this time.

0401170095 730206 PDR ADOCK 05000271 P PDR

O O' Mr. J. P. O 'Reilly July 21, 1972 We are continuing our investigation of manufacturing records in the hope that the wall thickness of additional valves can be verified from existing documentation. In addition, we will attempt tc identify those valves which, for any reason, were manufactured to ratings higher than actually required by service conditions. 'y In the meantime we have initiated a program to develop methods by -

which wall thickness can be physically verified. We are presently evalu-ating the use of ultrasonic and/or mechanical measuring techniques. The actual methods employed and the overall schedule will reflect considera-tion of attainable accuracy of ultrasonic devices, types of materials, surface conditions of castings, number and location of measurements, accessibility, radiation levels, etc.

We will inform you as to the details of our proposed program as quickly as they are complete or in any event as to its status in ninety days. The program we will propose will be based on completion within the three year period specified in your letter.

We trust that the above is responsive to your letter and, of course, are prepared to discuss this matt er at your convenience.

Very truly yours, VERMONT YANKEE INCLEAR POWER CORIORATION L. E. Minnick Vice President LM4/aj xs e

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