ENS 51800
ENS Event | |
|---|---|
20:15 Mar 17, 2016 | |
| Title | Valid Engineered Safety Feature System Actuation Due to Lightning Strike |
| Event Description | At 1515 [CDT] on March 17th 2016, Grand Gulf Nuclear Station received a valid actuation signal of the Division 2 Engineered Safety Feature (ESF) Load Shedding and Sequencing system. The actuation signal was most likely caused by a lightning strike to the offsite power source supplying this ESF bus. This caused a loss of the in service shutdown cooling system and associated system actuations.
Grand Gulf Nuclear Station (GGNS) was in Mode 5 at 85 [degrees] F coolant temperature. Reactor Cavity was flooded to High Water Level with a time to reach 200 [degrees] F of 7.5hrs. GGNS is conducting a planned refuel outage with core alterations in progress. Systems were aligned as follows: Division 2 Diesel Generator was OPERABLE and the associated ESF bus aligned to transformer ESF12 (115KV Port Gibson offsite feeder). Residual Heat Removal (RHR) system 'B' was in service in shutdown cooling being supplied from this ESF bus (16AB) with Alternate Decay Heat Removal available as a backup. Division 3 Diesel Generator was unavailable due to planned maintenance on support systems. The associated ESF bus was also aligned to transformer ESF12 (115KV Port Gibson offsite feeder). Division 1 Diesel Generator was available and the associated ESF bus aligned to the transformer ESF 11 (Switchyard offsite power feeders Baxter-Wilson and Franklin). Power was never lost to this bus. RHR 'A' and Low Pressure Core Spray (LPCS) were not available due to planned maintenance (tagged out of service). ESF 21 Transformer was out of service for planned maintenance. A suspected lightning strike caused a momentary perturbation in power in the 115KV Port Gibson line causing the Division 2 Load Shedding and Sequencing (LSS) system to actuate. This actuation caused a loss of Residual Heat Removal system 'B' due to being shed (expected). The Division 2 Diesel Generator started and tied onto the bus as expected, restoring power in 7 seconds. Shutdown cooling was restored at 1518 [CDT] and was out of service for 3 mins 13 sec. Reactor coolant and spent fuel pool temperatures remained at 85 [degrees] F throughout this scenario. Core Alterations were suspended and fuel placed in its designated location per the approved movement plan. Division 3 systems; High Pressure Core Spray, Standby Service Water System 'C', and Division 3 Diesel Generator were tagged out of service for planned maintenance. Division 3 Diesel Generator received a valid actuation signal but did not start due to being out of service. The Division 3 bus was restored manually to ESF 11. All safety systems operated as expected for the loss of power to ESF 12 and Division 2 LSS actuation. This is being reported under: 1. 10CFR50.72(b)(3)(iv)(A)-Specified system actuation; Division 2 LSS and Division 3 Diesel Generator start logic. 2. 10CFR50.72(b)(3)(v)(B)-RHR Capability; Loss of shutdown cooling. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Grand Gulf  Mississippi (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| LER: | 05000416/LER-2016-001 |
| Time - Person (Reporting Time:+3 h0.125 days <br />0.0179 weeks <br />0.00411 months <br />) | |
| Opened: | Sean Dunfee 23:15 Mar 17, 2016 |
| NRC Officer: | Steven Vitto |
| Last Updated: | Mar 17, 2016 |
| 51800 - NRC Website
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Grand Gulf with 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 570532024-03-26T16:15:00026 March 2024 16:15:00
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Remove Residual Heat, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Engineered Safety Feature System Actuation Due to Lightning Strike ENS 499202014-03-17T10:14:00017 March 2014 10:14:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Steam Leak in Low Pressure Turbine Line ENS 492252013-07-30T19:32:00030 July 2013 19:32:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Turbine Generator Trip ENS 477982012-04-02T20:11:0002 April 2012 20:11:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Autostart of Division 3 Diesel Generator Following 4160 Volt Line Outage ENS 476792012-02-20T01:04:00020 February 2012 01:04:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram During Shutdown Due to Lowering Reactor Vessel Water Level (Rvwl) ENS 450442009-05-06T04:27:0006 May 2009 04:27:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Auto-Start and Loading of Emergency Diesel Generator to Safety Bus Due to Undervoltage Condition ENS 446012008-10-26T16:25:00026 October 2008 16:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram and Isolation Due to Turbine Trip ENS 445952008-10-23T12:20:00023 October 2008 12:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram with Manual Rcic Initiation ENS 438992008-01-12T22:26:00012 January 2008 22:26:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Degraded Cooling to Main Transformers ENS 433762007-05-19T16:27:00019 May 2007 16:27:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Turbine Trip on Loss of Condenser Vacuum ENS 414052005-02-12T01:59:00012 February 2005 01:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Rps Actuation 2024-03-26T16:15:00 | |