05000327/LER-1980-149-03, /03L-0:on 800807,during Preoperational Tests, Turbine Driven Feedwater Pump Failed to Maintain Rated Rpm. Caused by Overheated Automatic Governor.Ventilation Damper Linkage Repaired & Governor Controls Replaced
| ML19344F122 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/04/1980 |
| From: | Gelston A TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML19344F101 | List: |
| References | |
| LER-80-149-03L, LER-80-149-3L, NUDOCS 8009120443 | |
| Download: ML19344F122 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| 3271980149R03 - NRC Website | |
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Tennessee Valley Authority Sequoyah Nuclear Plant 1.Elt SUFFLEMENTAL INFORMATION
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SQRO-50-327-/80149 Technical Specification Involved:
3.7.1.2 Reported Under Technical Specification: 6.9.1.&3.b Date of Occurrence: August 7, 1980 Time of Occurrence: 0905 EDT August 8, 1980 Time of Occurrence: 2130 EDT Identification and Description of Occurrence:
On August 7, 1980, at 0905 EDT, prior to performing the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> endurance run (preoperational test) a simulated safety injection signal to the auxil-iary feed water pumps was initiated. The turbine driven pump came up to rated rpm and pressure then in approximately 20 seconds fell to 2900 rpm at 850 psig discharge pressure. The pump was declared inoperable and action stater.ent 3.7.1.2 of the tech specs was entered.
The babsequent investigation could not duplicate the original problem but it was found that the auxiliary feedwater flow indicating controller, 1-FIC-46-57, was not operating correctly. This component was replaced realizing that it was not the cause of the problem. Since the problem could not be identified, the pump was returned to service and the preoperation-al test continued. Investigation of the problem continued.
On August 8, 1980, at 2130 EDT, during preoperational testing of the turbine driven auxiliary feedwater pump, the turbine reduced speed causing the pump output to fall below rated flow. The pump had been at rated flow for approximately 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />. The pump was declared inoperable and action state-ment 3.7.1.2 of the tech specs was entered.
Investigation indicates that the turbine speed governor components are over heating. When the cover to the cabinet, which houses the electronic governor components, was opened and the components allowed to cool, for about 30 minutes, the speed increased and automatic control was reestablished. The pump then operated at full flow for the next 28 consecutive hours.
Conditions Prior to occurrence:
Mode 2, power at approximately 1.5%, RCS at 545 degrees F and 2235 psig Action specified in the Technical Specification Surveillance Requitecents met due to inoperable equipment.
3.7.1.2 states that the pump must be operable within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in Mode 3 within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. The automatic governor components were cooled and automatic speed control was maintained within 30 minutes.
Apparent Cause of Occurrence:
The turbine speed governor components were apparently overheating and as a result failed to maintain proper control of the turbine speed.
N
. Sequoyah Nuclear Plant i
LER Supplemental Information Analysis of Occurrence:
One ventilation damper to the auxiliary feedvater pump (turbine driven) room was found closed with broken linkage which caused deficient cooling. Also a length of insulation was found missing from the piping to the steam traps in this room. Governor electronic components were located in a non-ventilated panel adjacent to the turbine skid. During the 30 minuta loss of automatic control, manual control was available.
Corre tive Action:
The ventilation damper linkage was repaired and missing piping insulation was replaced. To provide additional assurance, the electronic governor controls were replaced and are now relocated in a cooler area with a vented panel to allow natural circulation of air.
Future retesting will be performed to evaluate operability of electronic components of the turbine speed governor in the new location.
The electronic components of the turbine speed governor will be returned to tie vendor for failure analysis. The resulta vill be evaluated to determine future reportability, and the need for any future modifications.
Failure Data:
None
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