ML20084K733

Ro:On 720216,flow Switches in RHR Sys Failed.Caused by Removal of Switches from Sys.Broken Switch Paddles Lost in Sys Must Be Located

ML20084K733
Person / Time
Site:	Quad Cities
Issue date:	02/23/1972
From:	Palmer F COMMONWEALTH EDISON CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084K735	List: ML20084K733
References
FAP-72-41, NUDOCS 8305190530
Download: ML20084K733 (2)

Text

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Commonwealth Edison Company

- Q U A O-C ITIE S NUCLEAR POWER STATION _.

Addr.n n.pty raa ' \$ LLl$l -

FO$T OfDCE BOX 216

• CORDOVA, ILllNotS 61242 ..

'/ n as7 ,c r FAP-72-41 February 23, 1972_d r'}\l o /

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x. j s Dr. Peter A. Morris, Director W Division of Recctor Licensing \ - ; ' N'X v/ '

U.S. Atomic Energy Commission "

Unshington, D.C. 20545 SUBJhCT: License EPR Quad-Cities nuclear Power Station Unit 1 Failure.of flow switches used to monitor RHRS flow

REFERENCE:

' Diagram of RHRS piping sheet 1 - Quad-01 ties Station Unit 1 - M-37

Dear Dr. Morris:

This is to inform you about the failure of two flow monitoring switches in the residual heat removal system at Quad-Cities 'Huclear Power Station Unit 1. The discovery of.the failed switches on Wednesday, February 16, 1972 was the result of the physical removal

, of the devicen from the RHR system. The removal resulted from simular failure on Unit 2 which was reported by telephone to Mr. Ed Jordon on Friday, January 28, 1972.

Description of Flow Switches The flow sensing switches nre manufactured by Fower Engineering.'

and Equipment Co.,'Inc. of Torrance, California. The switches are on/off paddle type with the paddle physically located in the fluid i flow. path. The purpose of the switches is to monitor for minimum l' flow conditions'and control the. opening and closing of recirculation

, valves for' pump protection.

Paddles - The padilles are fabricated' from stainless steel sheet to' form n rectangular coometry of length ~10". and width 1-1/8".

The thickness is stepped from a maximum of ~3/16" at the lever end to'a' minimum thickness of ~1/32" at the top end.

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' COPY S5 TliEGION

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'..;~ i O O The thick end (3/16") conciats of 4 laminatione of ctainleon steel. At the point where the number of laminations goes from 4 to 3, the paddle in banded and uecured with three spot welds. At the point where the number of laminations goes from 4 to 2, the paddle in handed and secured with three apot welds. At the tip end (two laminations) the two chects are welded together.

Dencription of Failuren Upon removal of the flow switchec from the four RHR3 pumps, paddle failures were observed on two switches:

1) RHRS - Pump 1A-1002 - flow cuitch 1-1001-81A The paddle wan found to be missing completely.

The paddle had broken off at the point of attachment to the actuating lever for the switch.

2) RHR3 - Pump 1B-1002 - flow switch 1-1001-813 One 3 inch neccent of sheet material was found  !

to be missing and the assembly band.

i Thene piec"s of stainless steel are still in the RHRS system or the reactor recirculation cyntem and may present a potential nafety problem until located.

Procedure for Location of Pecco Switch Paddles

1) Visual inspections of all accencible piping in likely areas.

2) Visua] jnspections of suppression pool.

3) Radiograph sucpect valves and poscibly none selected piping nections.

4) Check operationc of all valves in system for full stroke.

5) Check jet pump flow raten.

pn f e ty nnal.yni s A cafety nnalynia is being prepared and will be submitted if the paddlec are not located.

Yours truly, COMMCIT.;EALTH EDI OR COMPANY

/

7 3,7 6 u/ j a, baf i

Frank A. Palmer Station Uuperintendent FAP/dch

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