ML20072C954
| ML20072C954 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/26/1983 |
| From: | Diederich G COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 8306210308 | |
| Download: ML20072C954 (1) | |
Text
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/^N. Commonwealth Edison
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) RuralRouts #1, Box 220LaSilla County Nucl:ar Station v
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7 Marseilles, Illinois 61341 i
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Telephone 815/357-6761 May 26, 1983
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Mr. James G. Keppler Regional Administrator Region ill U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Dear Sir:
This Special Report is being submitted to correct the Special Report submitted May 17, 1983, in accordance with LaSalle County Nuclear Station Technical Specification 3.5.1 Action i) concerning ECCS actuation and injection of water into the reactor coolant system.
On 3/22/83, at approximately 0509, UI reactor experienced a SCRAM on low reactor water level. The HPCS and RCIC systems auto initiated due to low reactor water level. The cause of the event follows:
On 3/22/83, at approximately 0503, the RR B FCV ramped open on a spurious signal resulting in a power increase from approximately 68% to 73%. The two TDRFP's were operating, one in single element control and the other in manual control.
FW Pump Three element control was not being used due to FW control testing and tuning. The 5% power change resulted in a reactor water level transient. The unit NSO attempted to re-establish vessel level by increasing FW flow at approximately 0505 and 0509 utilizing the FW Pump that was in manual control. The increases in FW flow and condensate flow resulted in abnormally low condensate pump discharge pressures.
There were correspondingly lower CB discharge and FW suction pressures. At approximately 0509:30, the HD pump forward valves closed, due to low HD tank level. Upon HD loss, the standby CD/CB pump auto started on low FW suction pressure and the FW pumps tripped on low suction pressure. The Rx subsequently auto scrammed on low Rx water level.
Rx wa te r l eve l reached a low level of approximately -48 inches before being restored by HP and RI auto initiation and the MDRFD.
Post Scram Calibration Verification showed HP and RI initiation setpoints to be more conservative than required by Tech Specs.
Other system trip setpoints that are required by Tech Specs to occur at
-50" were veri fied to be wi thin Tech Spec limits.
The total accumulated actuation cycles to date of the HPCS system into the reactor coolant system is one cycle.
The fatigue usage factor for the HPCS nozzle following the HPCS initiation of 3/22/83 has been determined to be 0.01533.
If there are questions concerning this Special Report, please contact J.
Renwick, LSCS Technical Staff Supervisor.
8306210308 830526 G.
. Diederich DR ADDCK 05000373 Station Superintendent S
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