ENS 48651
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ENS Event | |
|---|---|
15:41 Jan 4, 2013 | |
| Title | Unit 2 Manually Tripped After Two Shutdown Control Rods Unexpectedly Dropped During Surveillance Testing |
| Event Description | On January 4, 2013, at 0941 hours0.0109 days <br />0.261 hours <br />0.00156 weeks <br />3.580505e-4 months <br /> [CST], Unit 2 was manually tripped after 2 shutdown rods unexpectedly dropped during monthly control rod surveillance testing. Shutdown Bank C rods were being inserted in accordance with the surveillance procedure, when 2 rods in Shutdown Bank E (D-8 and M-8) unexpectedly dropped. This met the criteria for a manual reactor trip, which was immediately performed.
The appropriate procedures were entered to mitigate the transient and all systems responded as designed. Unit 2 is currently in Mode 3 and the cause of the 2 dropped rods is under investigation. All three (3) motor-driven and the steam-driven Auxiliary Feedwater Pumps started as required and have since been secured. Decay heat is being removed using normal startup feedwater with steam discharge to the main condenser via the bypass valves. Unit 2 is in a normal post trip electrical lineup. The licensee informed the NRC Resident Inspector. |
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-1.37 h-0.0571 days <br />-0.00815 weeks <br />-0.00188 months <br />) | |
| Opened: | Charles Ayala 14:19 Jan 4, 2013 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Jan 4, 2013 |
| 48651 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | Yes, Manual Scram |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
South Texas with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 568772023-12-02T12:10:0002 December 2023 12:10:00
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