ENS 44465: Difference between revisions
Jump to navigation
Jump to search
StriderTol (talk | contribs) (Created page by program invented by Mark Hawes) |
StriderTol (talk | contribs) (Created page by program invented by StriderTol) |
||
| Line 16: | Line 16: | ||
| event date = 07/23/2008 23:25 EDT | | event date = 07/23/2008 23:25 EDT | ||
| last update date = 09/05/2008 | | last update date = 09/05/2008 | ||
| title = Invalid System Actuation Due | | title = Invalid System Actuation Due to Loss of One Offsite Power Circuit to Safety Buses | ||
| event text = This 60-day report, as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10CFR50.73(a)(2)(iv)(A) to describe an unplanned, invalid actuation of specified systems, specifically the Units 2 and 3 Primary Containment Isolation Systems (PCIS). On 7/23/08, at approximately 2325 hours, Units 2 and 3 experienced invalid Primary Containment Isolation System (PCIS) partial isolations. Unit 2 experienced an outboard PCIS Group II isolation, while Unit 3 experienced inboard and outboard PCIS Group II isolations. The isolations involved various process lines including Reactor Water Cleanup (RWCU), Containment Atmospheric Control (CAC) / Containment Atmospheric Dilution (CAD), Drywell Sumps, and Containment Instrument Nitrogen. The Units 2 and 3 PCIS isolations were reset by approximately 2350 hours in accordance with procedures. All required isolation valves operated as designed. | | event text = This 60-day report, as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10CFR50.73(a)(2)(iv)(A) to describe an unplanned, invalid actuation of specified systems, specifically the Units 2 and 3 Primary Containment Isolation Systems (PCIS). On 7/23/08, at approximately 2325 hours, Units 2 and 3 experienced invalid Primary Containment Isolation System (PCIS) partial isolations. Unit 2 experienced an outboard PCIS Group II isolation, while Unit 3 experienced inboard and outboard PCIS Group II isolations. The isolations involved various process lines including Reactor Water Cleanup (RWCU), Containment Atmospheric Control (CAC) / Containment Atmospheric Dilution (CAD), Drywell Sumps, and Containment Instrument Nitrogen. The Units 2 and 3 PCIS isolations were reset by approximately 2350 hours in accordance with procedures. All required isolation valves operated as designed. | ||
The invalid PCIS isolations were a result of a fast transfer on associated 4 kV safety-related electrical buses for Units 2 and 3 caused by a loss of one of the two off-site power circuits that supply the 4 kV buses. This fast transfer resulted in a momentary voltage transient on electrical power supplies to the logic for the Units 2 and 3 PCIS. The two station off-site power circuits are fed from three offsite sources. The loss of the offsite power circuit was caused by failure of the 'A' phase of the '#1' transformer, which is associated with one of the three offsite power sources. This transformer is located at the North Substation. The transformer automatically isolated as a result of a fire associated with this transformer and resulted in the loss of two of the three offsite power sources. Subsequent to fire extinguishment, appropriate electrical switching was performed and the offsite power circuit was returned to an operable status by 0650 hours on 7/24/08. | The invalid PCIS isolations were a result of a fast transfer on associated 4 kV safety-related electrical buses for Units 2 and 3 caused by a loss of one of the two off-site power circuits that supply the 4 kV buses. This fast transfer resulted in a momentary voltage transient on electrical power supplies to the logic for the Units 2 and 3 PCIS. The two station off-site power circuits are fed from three offsite sources. The loss of the offsite power circuit was caused by failure of the 'A' phase of the '#1' transformer, which is associated with one of the three offsite power sources. This transformer is located at the North Substation. The transformer automatically isolated as a result of a fire associated with this transformer and resulted in the loss of two of the three offsite power sources. Subsequent to fire extinguishment, appropriate electrical switching was performed and the offsite power circuit was returned to an operable status by 0650 hours on 7/24/08. | ||
Latest revision as of 22:13, 1 March 2018
| Where | |
|---|---|
Peach Bottom  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1037.33 h43.222 days <br />6.175 weeks <br />1.421 months <br />) | |
| Opened: | Dave Foss 08:45 Sep 5, 2008 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Sep 5, 2008 |
| 44465 - NRC Website
| |