ML19261F251

Environ Rept 76-34/3L:on 760922,reactor Bldg Isolation Valve CA-V4A Failed to Fully Close on Remote Control Room Signal. Caused by Loose Lock Nut on Valve Operator Allowing Stem Nut to Move Out of Position,Not Allowing Valve to Close

ML19261F251
Person / Time
Site:	Three Mile Island
Issue date:	10/20/1976
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-1436, NUDOCS 7910250683
Download: ML19261F251 (4)

Text

t NRCFOnM 195 U.s. NUCLE AR REcvLATORY ( AISSION DOCKET NUMBE R (2 76)30-239 NRC DISTRIBUT.lON FOR PART 50 DOCKET MATERI AL 77 CID$.7 REPORT TO: FROM: D ATE OF DOCUMENT Metropolitan Edison Company 10/20/75

' r. James P. O'Reilly Reading, Pa. o47s Receivco R. C. Arnold 11/3/76 MLETTER O NOTO RIZ E D PROP tNPUT FORM NUMBER OF COPIES RECEIVE D JiEoRiciN A L KUNC LASSIFI E D One signed CCOey DESCRIPTION EN CLOSU R E Licensee EvCnt Report (R0 50-239/76-34/3L)

On 9/22/76 concerning failure of Reactor 3uildin; Isolation Valve to fully close on a Remote Signal. .

ACKNOWLEDGED o-P)

DONOT REMOVE PIANT NAME: NOTE: IF PERSOITNEL "r.J':POSURE IS INVOLVED Three Mile Island 41 SEND DIRECTLY TO KREGER/J. . COLLINS FOR ACTION /INFORMATION ll/4/76 RJL

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POST OFFICE BOX 542 READING, PENNSYLV ANI A 19603 TELEPHONE 215 - 929-3601

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October 20, 1976 ^?,

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Mr. J. P. O'Reilly, Director Office of Inspections and Enforcement, Regicn 1 ,

U.S. :iuclear Regulatory Cc==ission 631 Park Avenue x; King of Prussia, Pa.

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Dear Sir:

Docket Ilo. 50-289 Cperating License :;o. DPR-50 In accordance with the Technical Specifications of our Three Mile Island Nuclear Station Unit 1 (TMI-1), we a'e reporting the following reportable occurrence:

1. Report Number: ER T6-3h/3L

2. a. Required Report Date: 10/22/76

b. Date of Cccurrence : 9/22/76 3 Facility: Three Mile Island Nuclear Station - Unit 1

h. Identification of Occurrence:

Title:

Failure of Reactor Building Isolation Valve to Fully Close en a Remote Signal Type : A reportable occurrence as defined by Technical Specificaticns 6.9 2.3(2) in that the Reactor Building Isolation Valve, CA-VhA failed to fully close on a remote signal from the Control Room, thus leading to operaticn in a degraded =cde permitted by a limiting condition for cpe defined by Technical Specifications 3.6.6. b_. D N

5 Conditions Prior to Occurrenc . N Power: Core: 251h !Gt 6}f .

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Mr. J. P.'O'Reilly October 2% I?76 G;L 1k36 RC Flow: 1h1 x 10 lbs./hr.

RC Pressure: 2155 psis RC Te=p. : 579 F PRZR Level: 22h Inches PRZR Te=p.: 652 F

6. Descriptica of Occurrence:

At 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> en Septe=ber 22, 1976, the Centainment Isolation Valve, CA-VhA, failed to fully close when actuated by its remote control switch. The incident occurred when terminating a sample frc= Steam Generator "A." This ecnstituted operation in a degraded mode since cnly cne of the two isolatica valves was cperaticnal. I:=ediately the Steam Generatcr "A" sa=ple line redundant isolation valve, CA-VSA, was closed and tagged.

7. Designation of Apparent Cause of Occurrence:

The cause of this occurrence has been determined to be material in that a loose lock nut en the valve operator caused the failure. The loose lock nut allowed the ste= nut to move out of its nor=al position on the valve ste=. Thus, when the valve was closed, the ste= nut came out of positicn to the point that the valve would not close ec=pletely.

The contact mechanis= for the opening torque switch was found broken.

'4 hen the valve was given an cpen signal, it traveled until the cpen contactor de-energized due to the open torque switch, which stopped the travel. This caused the inter =ediate pcsition indication. The brcken torque switch is not related to failure of the valve to close.

8. Analysis of Occurrence:

It has been determined ;--t the occurrence did not constitute a threat to the health and safety of the public in that:

a. One (1) containment isolation valve is sufficient to isolate Stea=

Generator "A" sa=ple line in the event of a loss of coolant accident.

b. The redundant centain=ent isolation valve for the Stea= Generator "A" sa=ple line, CA-VSA, was operable.,

9 Corrective Action:

I:=ediate: The valve ste= nut was placed in the proper pcsition and its icek nut tightened. The torque switch was replaced. CA-VLA checked cut satisfactorily and returned to service.

148p1 254

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Mr. J, P. O'Reilly cetober 20, 1976 GQL lh36 Lcng Ter=: In addition to the i==ediate corrective action described above, inspection and trouble shooting of similar valve operators for proper securing of the valve operators lock nut vill be perfor=ed.

The Plant Operators Review Co==ittee and Unit Superintendens have reviewed and approved the above corrective acticn and have taken steps to assure its completion.

10. Failure Data:

Valve Operator Valve Manufacturer: Limitorque 1" - 1500s/ Globe Stop Valve Type / Size: St.G-000 Rockwell Mfg. Co.

Motor: Reliance Fig. 362h (F316) JM h60V 30 Socket Weld End 60 hz 316 Stainless Steel Body 0.95 A=ps Operating Press. 1050 psig Type P Cperating Te=p. 6000F 1700 RPM K h8 Frame :To.

2 ft. lbs. start

. h ft . lbs. run Si=ilar Events:

A0 75-06 (RR-V3C loose lock nut)

The loose lock nut previously reported was on an SI2 C.

The ste= nut on that valve is different than on CA-VhA and, therefore, the failure is not identical.

Sincerely,

[

R. C. .. _ id Vice President RCA:DGM:=ft

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