ML20235F169

Ro:On 721020,boot Seal on Air Operated Reactor Bldg to Suppressio Chamber Vacuum Breaker Valve Found Depressurized. Caused by Excessive Clearance Between Actuating Arm & Valve. Procedural Changes Being Initiated

ML20235F169
Person / Time
Site:	Monticello, 05000000
Issue date:	11/15/1972
From:	Mayer L NORTHERN STATES POWER CO.
To:	Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20235B311	List: IA-87-111, Submits Rept on Plant,As Discussed in ACRS 150th Meeting on 721012-14.Listed Items Can Be Resolved During Const & Facility Can Be Constructed W/Reasonable Assurance for Operation W/O Undue Risk to Public Safety IR 05000254/1972009 IR 05000358/1972003 IR 05000358/1973001 IR 05000358/1973002 IR 05000358/1973003 IR 05000358/1973005 IR 05000358/1973006 IR 05000358/1973007 IR 05000358/1974001 IR 05000358/1974002 IR 05000358/1974003 IR 05000358/1975004 ML20235B308 ML20235B364 ML20235B401 ML20235B405 ML20235B424 ML20235B456 ML20235B461 ML20235B465 ML20235B477 ML20235B488 ML20235B507 ML20235B552 ML20235B582 ML20235B585 ML20235B588 ML20235B605 ML20235B618 ML20235B623 ML20235B649 ML20235B656 ML20235B662 ML20235B670 ML20235B679 ML20235B683 ML20235B687 ML20235B702 ML20235B708 ML20235B713 ML20235B714 ML20235B718 ML20235B720 ML20235B730 ML20235B734 ML20235B748 ML20235B754 ML20235B762 ML20235B764 ... further results
References
FOIA-87-111 NUDOCS 8709280441
Download: ML20235F169 (1)

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DTEG NORTMERN STATES POWER C O M P A'N Y Minneapolis, Minnesota 55401 Evember 15, 1972

/y" Mr. A. Giambusso Deputy Director for Reactor Projects

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United States Atomic Energy Connisaien i t

Washington, D. C.

20545 Dy

Dear Mr. Giambusso:

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10EICEll.0 WCLEAR G3CIAi!E PLAW Docket %. 50263 Liconse No. DP&22 Inoperability of Primery Containment Valve Boot Seals A mndition occurred at the %nticello helear Generatirig Plant recently which we are reporting to your office in accordance with provisions of Section 6.6.C.1 of ndix A, Technical Specifications, of the Provisional Operating License DPS On October 20, 1972, the boot seal on an air operated reactor building to suppression chamber vacuum breaker valve (A0 2380) was found depressurized.

A subsegaont investigation of all d 11 and suppression chamber vent and purge valves of the same design as A0 2

, revealed a second valve (A0 2387) with the seal depressurized. A0 23Erl is the outboard drywell vent velve. These valves are of a butterfly type design with an inflatable rubber seal for positive valve disc sealing.

When the valves are in a closed position, an actuating arm attached to the valve shaft oports a boot seal pilot valve, allowing air pressure to the seal.

Examination of the valves on October 20th revealed that the pilot and the pilot valve. valve was not being actuated due to excessive clearance betwee Immediately upon discovery of this problem, the boot seals for both valves I

automatic inflation of the boot seal upon valve closure was verifled.Subs were pressurized.

Procedaral changes are being initiated to insure that the boot seal pressure gauges on all primary containment valves are checked as part of the regularly scheduled Surveillance i

Test Program.

A S.gnificant Operatin l

Operstions inspector. g Event report will be available at the site for Regulatory I

Yours ver truly, k.N h.h.

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Tu LU, L}g L 0 Mayer, P..

Director of Nuclear Support Services 2gg BMD S350 cc: 8 H Grier 8

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