ML19261F251
| 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$.7 REPORT TO:
FROM:
D ATE OF DOCUMENT Metropolitan Edison Company 10/20/75
' r. James P. O'Reilly Reading, Pa.
o47s Receivco R. C. Arnold 11/3/76 MLETTER O NOTO RIZ E D PROP tNPUT FORM NUMBER OF COPIES RECEIVE D JiEoRiciN A L KUNC LASSIFI E D One signed CCOey DESCRIPTION EN CLOSU R E Licensee EvCnt Report (R0 50-239/76-34/3L)
On 9/22/76 concerning failure of Reactor 3uildin; Isolation Valve to fully close on ACKNOWLEDGED a Remote Signal.
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PIANT NAME:
NOTE:
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POST OFFICE BOX 542 READING, PENNSYLV ANI A 19603 TELEPHONE 215 - 929-3601
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October 20, 1976
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Mr. J. P. O'Reilly, Director Office of Inspections and Enforcement, Regicn 1 U.S. :iuclear Regulatory Cc==ission 631 Park Avenue x;
King of Prussia, Pa.
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Dear Sir:
Docket Ilo. 50-289 Cperating License :;o. DPR-50 In accordance with the Technical Specifications of our Three Mile Island Nuclear Station Unit 1 (TMI-1), we a'e reporting the following reportable occurrence:
1.
Report Number: ER T6-3h/3L 2.
a.
Required Report Date: 10/22/76 b.
Date of Cccurrence :
9/22/76 3
Facility: Three Mile Island Nuclear Station - Unit 1 h.
Identification of Occurrence:
Title:
Failure of Reactor Building Isolation Valve to Fully Close en a Remote Signal Type : A reportable occurrence as defined by Technical Specificaticns 6.9 2.3(2) in that the Reactor Building Isolation Valve, CA-VhA failed to fully close on a remote signal from the Control Room, thus leading to operaticn in a degraded =cde permitted by a limiting condition for cpe defined by Technical Specifications 3.6.6.
b_.
D N
5 Conditions Prior to Occurrenc N
6}f 2.
Power:
Core:
251h !Gt jj y,,,
l 44 A n
Elec:
3h0 INe (1
1..I. L'l
,l
\\i~
~COalM:="===ca s
2$q M I*'E42 v
s 1481 253
/ of 14-
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
- i. ~
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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