ML20084J180

Ao:On 721020,during Testing,Hpci Turbine Stop Valve Would Not Open.Caused by Bent Valve Stem.Stem Replaced

ML20084J180
Person / Time
Site:	Quad Cities
Issue date:	11/03/1972
From:	Palmer F COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084J183	List: ML20084J180 ML20084J189 ML20084J193
References
FAA-72-199, NUDOCS 8305120222
Download: ML20084J180 (2)

Text

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Y Comm e Ith Edison

/ , GuarC; Ocier ;w.m Sta9on Pr! OSce Box 216

• Cedca Mom 61242 T M aphone 303/05 ;-2241

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n . Denuty Director for Peactor Projects Directorate of Licensine U. S. Atomic Enert,' Commission

'dashincton, D. o. 2054; Re fe re n ce : ^uad-rities "uclear Power Station Unit 2 License DT -30, Appendix A '

Sections 1.3.A.2, 3.5.C, and 6.4.B.3

Dear Vr. 11ambusso:

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". " .I The purpose of tnin letter is to inform you of the details * ;;

regardinr an incident involving the HPCI System at Quad- -

Cities Unit 2. Tnis abnormal occurrence was reported to . -

vou by telegram on Oc tober 21, 1972. ,,

DES CRIPTIC': OF INCIDENT At 1855 on October 20, 19 72, with the Unit 2 reactor at 45 per cent power, the HPCI S7ste:1 was to be run in con-f unction with a special test designed to monitor torus creasure waves and displacement duri'1g an electromatic relief valve actuation and HPCI operation. Tne HPCI I

tur"ine stop valve sould not cpen, however, and the sys tem was de clared inoperable. Additional surveillance

///O required by the Technical Specifications was conducted.

The unit was tc be shutdown on Octooer 21, f'or maintenance.

The investigation into the stop valve problem was later

/ complicated by a 250 Vdc ground and the railure cf eteam M admission valve '40 2-2301-3 IN7ESTIGATIONS On the evening of October 20, an inspection of the turbine stop valve trip and reset mechanism was made. The valve was capable of being reset locally, but it could not be held open. The problem appeared to be either a sticking 9'O i

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• 4 r . A. 'liamtusse November 3, 1c72 l

• r!r Solenoid or defective operating cylinder.

, Oil pressures ere normal and the reset relav, primary staton and secondary operatinc cylinder were found to be in sn*'= factory condition.

Additiocal t re it h shoctin7 w as to be conducted the next

, d a'. , however, ihile the unit was being cooled down, the "DCI t urb ine aperated cetisfactorily at '045 on October 21, 10 I?. Atternts later in tne day to duplicate the problem uith the stop valve were unsuccessful.

Durin7 these investlyations it was observed that numeraous alarms were received each time the control swit ch for the metor operated steam valve to the HPCI t urbine , v.C 2-ml-3, was cut in the CLOSF r odt ion .

In addition to the unrelated alarms, all of the indicating lights on panel 972-3 blinked. The swit ch for the 2301-3 valve was put te the close position several tims during the day while looking for a cround in the system. Since this valve has a seal-in feature to close the valve and a torque switch to stop closure, each time that the switch was put to the close position the valve motor started and applied a torque to the valve stem until it was tripped by the torque swit ch. At 1830 on October 21, the ~ valveltem

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was found to be bent.

CORRECTIVE ACTInN The cause of the spurious alarms was traced to a ground on the strip heaters inside the 2A Bus (250 vde) cabinet.

The hesters have been disconnected. A replacement valve stem was obtained from the Dresden Nuclear Power Station and the valve was returnen to service at 2225 on retober 22, 1972. All operators have been cautioned against attemnting to close an already closed valve with a seal-in feature.

very truly yours, COMMONWE ALTH EDISON COMPANY OUAD-CITIES NUCLEAR POWER STATION e

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$ 8 Y n y,ya .u ' %fe t F. A. Palner Superintendent PAP /cm l' J