ENS 45071: Difference between revisions
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StriderTol (talk | contribs) (Created page by program invented by StriderTol) |
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| event date = 05/15/2009 05:19 EDT | | event date = 05/15/2009 05:19 EDT | ||
| last update date = 05/15/2009 | | last update date = 05/15/2009 | ||
| title = Group 1 Isolation | | title = Group 1 Isolation of All Main Steam Valves While Performing a Special Procedure | ||
| event text = At 0519 on 5/15/09, a Group 1 isolation signal was received which resulted in all eight Main Steam Isolation Valves closing. The signal was received based upon a valid main condenser low vacuum signal coincident with reactor mode switch placed in RUN position. The isolation was an unanticipated result of a special purpose procedure which was being performed as a functional test for maintenance work that had been performed on intermediate range nuclear instrumentation. The procedure had installed jumpers to bypass the Group 1 isolation for Mode Switch in Run, but did not account for low condenser vacuum isolation. The low condenser vacuum switches were in the bypass position, but this logic does not prevent Group 1 isolation in the Run mode. The Group 1 isolation was completed successfully with all MSIVs and small bore valves closing as designed. MSIV closure with Mode Switch in Run position also caused a RPS actuation / full scram. The reactor was subcritical and all control rods were already fully inserted as the reactor was being maintained in Cold Shutdown. | | event text = At 0519 on 5/15/09, a Group 1 isolation signal was received which resulted in all eight Main Steam Isolation Valves closing. The signal was received based upon a valid main condenser low vacuum signal coincident with reactor mode switch placed in RUN position. The isolation was an unanticipated result of a special purpose procedure which was being performed as a functional test for maintenance work that had been performed on intermediate range nuclear instrumentation. The procedure had installed jumpers to bypass the Group 1 isolation for Mode Switch in Run, but did not account for low condenser vacuum isolation. The low condenser vacuum switches were in the bypass position, but this logic does not prevent Group 1 isolation in the Run mode. The Group 1 isolation was completed successfully with all MSIVs and small bore valves closing as designed. MSIV closure with Mode Switch in Run position also caused a RPS actuation / full scram. The reactor was subcritical and all control rods were already fully inserted as the reactor was being maintained in Cold Shutdown. | ||
The licensee has notified the NRC Resident Inspector. | The licensee has notified the NRC Resident Inspector. | ||
Latest revision as of 21:12, 1 March 2018
| Where | |
|---|---|
Hatch  Georgia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+0.9 h0.0375 days <br />0.00536 weeks <br />0.00123 months <br />) | |
| Opened: | Edwen Urquhart 10:13 May 15, 2009 |
| NRC Officer: | Bill Huffman |
| Last Updated: | May 15, 2009 |
| 45071 - NRC Website
| |