ML20147A343
| ML20147A343 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 07/18/1982 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1982-024-00 | |
| Download: ML20147A343 (1) | |
Text
LER 334/82-024 Event
Description:
Transient with Two CCW Pumps Inoperable Date of Event:
July 18, 1982 Plant:
Beaver Valley 1 Summary During plant startup on July 18, 1982, a high-temperature alarm came in on the B component cooling water (CCW) system pump bearing. Steam generator blowdown was isolated to decrease the load on the system and pump B was shut down. Pump C was out for maintenance as well.
Pump A remained operable. The B pump bearing had failed due to an apparent motor/pump misalignment. Pump B was restored to service 43 hours4.976852e-4 days <br />0.0119 hours <br />7.109788e-5 weeks <br />1.63615e-5 months <br /> later. On the same day, an auto scram occurred due to a high B steam generator level.
This event was modeled as a transient with one train of the CCW inoperable. The CCW has three pumps and two trains. Two pumps provide flow to two trains. The third pump can supply flow to either train in the event that a pump fails. One pump is sufficient to supply CCW to one train of the residual heat removal (RHR) system heat exchangers and pump seal coolers as well as the reactor coolant pump (RCP) thermal barriers, motor lubrication oil coolers and motor air coolers.
One train of RHR and HPR was set to failed to reflect the failure of the two CCW pumps on a single RHR pump train. The main feed water (MFW) train was set to failed and the non-recovery probability was set to 0.1 to reflect the isolation of MFW due to the high B steam generator level trip. The estimated conditional core damage probability for this event is 3.5x10-6. The dominant sequence did not involve the loss of HPR or RHR, but the failure of auxiliary feed water, the failure of main feedwater, and the failure of feed and bleed.