05000237/LER-1979-002-01, /01X-1 on 790103:during Normal Operation,Hpci Turbine Failed to Start During Quarterly Flow Test.Caused by Partial Engagement of Interlock Dump Valve Operating Lever. Lever Adjusted.Hpci Started to Verify Operability
| ML19261D627 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/05/1979 |
| From: | Parcell COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML17173A922 | List: |
| References | |
| LER-79-002-01X, LER-79-2-1X, NUDOCS 7906200409 | |
| Download: ML19261D627 (2) | |
| Event date: | |
|---|---|
| Report date: | |
| 2371979002R01 - NRC Website | |
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LICENSEE EVENT REPORT UPDATE REPOPT i
PREVIOUS REPORT DATE:
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t,0 G1 DOCKET NUMB ER L2 09 EVENT DATE 74 7S REPORT DATE 80 EVENT OtSCRIPTION AND PROBABLE CONSEQUENCES h HPCI
- o 2 l During normal operation. HPCI turbine failed to start during omrearly fl ev ene _
declared inoperable and required ECCS surveillances (T.S.3.5.C.2) commenced. During l
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later testing, HPCI operated successfully six consecutive times. HPCI then declared l
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!i o l On 1/4/79. technical reoresentativa noted oartial eneagement of interlock duma valve l
operating lever. Lever adjusted.
HPCI started to verify operability. During re-g i
i l fueling outage 4/79 found control oil restriction in motor speed changer pilot valve 7
prevented full electric positioner piston travel. Relieved restriction. Will inspect; 3
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t ATTACHMENT TO LICENSEE EVE'IT REPORT 79-02/01r-1 COMMONWEAL'ni EDISON COMPANY (CWE)
DRESDEN UNIT (ILDRS-2)
DOCKET # 050-237 With the unit operating at steady load, the HPCI turbine failed to start during performance of quarterly flow test surveillance DOS 2300-3. Uhen the motor speed changer was run from the low speed stop to the high speed stop, the turbine control valves did not open. As a result the HPCI s stem was declared inoperable and the required ECCS surveillances (T.S. 3.5.C.2) commenced. At 1430 the HPCI surveillance was performed again and the HPCI turbine started on the second attempt. Six consecutive turbine startups were performed and the surveillance successfully completed. The HPCI system was declared operable. This event has minimal safety significance since the required ECCS surveillances with the exception of auto blowdown were completed.
The auto blowdown surveillance was terminated when HPCI was declared operable.
On 1/4/79 at 1100 the HPCI turbine was operated with the General Electric Technical representative present. He noted that the pin on the motor speed changer linkage which actuates the interlock dump valve when the motor speed changer is on the low speed stop was not fully depressing the interlock dump valve operating lever. The purpose of the interlock dump valve is to prevent the control valves from opening during system startup with the turbine reset and the motor speed changer not on the low speed stop. The interlock dump valve actuating lever was adjusted to provide full engagement and HPCI pump and valve operability surveillance DOS 2300-1 successfully performed at 1400.
During the Unit 2 refueling outage on 4/79, the General Electric Technical representative made an inspection of the HPCI turbine control system. This included checking linkage measurements and piston travel during control system operation. He found that the electric positioner piston did not fully re-tract to the required position when the motor speed changer is run to the low speed stop.
The pin discussed above is connected to the electric po-sitioner piston rod.
This accornts for the adjustment required previously to effect proper interlock dump valve operation. Further investigation revealed that an oil restriction existed in the motor speed changer pilot valve resulting in incomplete venting of the control. oil;from.;the electric positioner piston. When the restriction ptoblem was rectified, the control system was verified to operate properly.
It is planned to perform a similar control system inspection on the Unit 3 HPCI turbine during the next Unit 3 refueling outage.
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