ENS 42237: Difference between revisions
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| event date = 12/31/2005 14:12 CST | | event date = 12/31/2005 14:12 CST | ||
| last update date = 01/06/2006 | | last update date = 01/06/2006 | ||
| title = Automatic Actuation | | title = Automatic Actuation of the Emergency Feedwater (Efw) Due to a Transient on the "B" Main Feedwater (Mfw) Pump | ||
| event text = The EFW actuation occurred when the 'B' MFW pump RPM rose then dropped to ~4000 rpm. The MFW pump then recovered immediately. This transient caused EFIC [Emergency Feedwater Initiation Control] to actuate and both EFW pumps received start signals on invalid low SG level from the EFIC low range level instruments. These instruments measure level based upon a dp [differential pressure] across an orifice and are not considered reliable at 95% power and full MFW flow. All other SG level instruments indicate SG level was above EFIC setpoint during the MFW pump transient. This can be concluded by reviewing the OTSG [Once Through Steam Generator] level prior to and during the transient. Prior to the transient the EFIC low range level instruments indicated a level of ~24 inches. During the transient the EFIC low range level instruments indicated as low as 4 inches. However, the Startup Range level only lowered from ~122 inches prior to the transient to ~120 inches. | | event text = The EFW actuation occurred when the 'B' MFW pump RPM rose then dropped to ~4000 rpm. The MFW pump then recovered immediately. This transient caused EFIC [Emergency Feedwater Initiation Control] to actuate and both EFW pumps received start signals on invalid low SG level from the EFIC low range level instruments. These instruments measure level based upon a dp [differential pressure] across an orifice and are not considered reliable at 95% power and full MFW flow. All other SG level instruments indicate SG level was above EFIC setpoint during the MFW pump transient. This can be concluded by reviewing the OTSG [Once Through Steam Generator] level prior to and during the transient. Prior to the transient the EFIC low range level instruments indicated a level of ~24 inches. During the transient the EFIC low range level instruments indicated as low as 4 inches. However, the Startup Range level only lowered from ~122 inches prior to the transient to ~120 inches. | ||
Both EFW pumps were immediately overridden and stopped once it was verified this was not an actual under feed condition to the OTSGs. No EFW injection into the OTSGs occurred due to the EFW actuation. | Both EFW pumps were immediately overridden and stopped once it was verified this was not an actual under feed condition to the OTSGs. No EFW injection into the OTSGs occurred due to the EFW actuation. | ||
Latest revision as of 21:19, 1 March 2018
| Where | |
|---|---|
Arkansas Nuclear  Arkansas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+-0.93 h-0.0388 days <br />-0.00554 weeks <br />-0.00127 months <br />) | |
| Opened: | Richard Harris 19:16 Dec 31, 2005 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Jan 6, 2006 |
| 42237 - NRC Website
| |