ENS 44605
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ENS Event | |
|---|---|
04:42 Oct 26, 2008 | |
| Title | Valid Safety Injection Signal Due to Maintenance Error |
| Event Description | At approximately 2342 on 10/25/2006, while performing maintenance on the solid state protection system in Mode 5 cold shutdown, Unit 2 received an automatic safety injection signal which resulted in all three ESF Diesel Generators starting and a containment ventilation isolation and containment phase A isolation. All safety injection pumps were in pull-to-lock per plant conditions so that the pumps did not start and no water was discharged into the reactor coolant system. As a result, the ESF Diesel Generators started but did not load as designed. The residual heat removal pumps were stripped from the ESF electrical busses due to the actuation. The first residual heat removal pump was restored within 4 minutes upon the loss of residual heat removal cooling and the second pump was restored within 6 minutes. The residual heat removal system heat exchangers were bypassed at the time of the event and the plant was being allowed to heat up.
The cause of the automatic safety injection signal was an inadvertent removal of the block for the low pressurizer pressure safety injection system during the maintenance. Therefore, the signal was a valid signal initiated in response to a parameter satisfying the requirements for initiation of the safety function of the system. Although the actuation was the result of a valid signal, safety injection was not required in this Cold Shutdown Mode of Operation. This notification is being made under 10CFR50.72(b)(3)(iv) as an event that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section. This actuation was initially determined to be due to an invalid signal. Upon further review, it was determined at 1745 on 10/27/08 that the actuation was due of a valid signal. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+38.65 h1.61 days <br />0.23 weeks <br />0.0529 months <br />) | |
| Opened: | Klay Klimple 19:21 Oct 27, 2008 |
| NRC Officer: | Jason Kozal |
| Last Updated: | Oct 27, 2008 |
| 44605 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 571242024-05-12T21:41:00012 May 2024 21:41:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 568772023-12-02T12:10:0002 December 2023 12:10:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Auto Start of Emergency Diesel Generator ENS 556922022-01-06T12:03:0006 January 2022 12:03:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Auto Start Emergency Diesel Generator ENS 546052020-03-24T15:46:00024 March 2020 15:46:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Auto Start Emergency Diesel Generators ENS 543512019-10-25T01:51:00025 October 2019 01:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Undervoltage Actuation During Edg Sequencer Maintenance ENS 518972016-05-02T01:21:0002 May 2016 01:21:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Generator Lockout ENS 516872016-01-27T05:25:00027 January 2016 05:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Loss of Feedwater to a Single Steam Generator ENS 516152015-12-21T21:33:00021 December 2015 21:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Feedwater Isolation ENS 496662013-12-20T04:33:00020 December 2013 04:33:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Main Steam Isolation Valves That Was Not Part of a Preplanned Sequence ENS 486592013-01-08T22:40:0008 January 2013 22:40:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Main Transformer Fire ENS 486512013-01-04T15:41:0004 January 2013 15:41:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Manually Tripped After Two Shutdown Control Rods Unexpectedly Dropped During Surveillance Testing ENS 474852011-11-29T09:29:00029 November 2011 09:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Turbine Trip on Generator Lockout ENS 463872010-11-03T15:21:0003 November 2010 15:21:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to an Explosion in the Protected Area Which Affects Normal Operations ENS 462982010-10-01T00:04:0001 October 2010 00:04:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Standby Diesel Generator Autostart Due to Loss of a Switchyard Bus During Maintenance ENS 461912010-08-20T20:25:00020 August 2010 20:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to an Inadvertent Turbine Trip Signal During Testing ENS 446052008-10-26T04:42:00026 October 2008 04:42:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Safety Injection Signal Due to Maintenance Error ENS 404732004-01-23T22:16:00023 January 2004 22:16:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to High-High Steam Generator Level 2024-05-12T21:41:00 | |
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