ENS 41987
ENS Event | |
|---|---|
06:13 Sep 14, 2005 | |
| Title | Automatic Reactor Scram on Low Reactor Vessel Water Level During Planned Maintenance |
| Event Description | An automatic reactor scram on low reactor water level occurred following a momentary loss of the UPS (Uninterruptible Power Supply) system. The power loss resulted in a lock-out of the RFP (Reactor Feed Pump) controls. The HPCI system started on low reactor level but did not inject, reactor level had risen above the initiation set-point. The RCIC did not receive an initiation signal. Overall plant response was as expected.
Prior to the transient the licensee was in the process of transferring UPS electrical loads to the alternate power supply. The momentary loss of UPS power locked-out the RFP controls during a downtrend in the reactor water level from the normal 201-203 inch operating band. Before Operators could establish manual control, reactor water level reached the 177 inch scram setpoint. Following the scram, reactor water level continued to decrease to the HPCI and RCIC initiation setpoint of 126 inches before recovering. HPCI received a start signal but RCIC did not for reasons under investigation. The unit will remain in mode 3 pending the results of the post-scram investigation and restart. The licensee informed the NRC Resident Inspector and is planning on issuing a press release.
On September 14, 2005 at approximately 0213. an automatic reactor scram on low reactor water level occurred following a momentary loss of the UPS (Uninterruptible Power Supply) system. The power loss resulted in a lock-out of the RFP (Reactor Feed Pump) controls. A level transient occurred causing reactor water level to lower, resulting in an automatic reactor scram on low reactor water level. The HPCI system auto initiated on low reactor water level but did not inject as reactor water level had risen above the initiation setpoint. The RCIC system auto initiated (and sealed-in) and injected into the reactor vessel. Both systems operated as designed. In addition, a Primary Containment Isolation System (PCIS) Group 2 isolation occurred, resulting in multiple system isolations. This included isolation signals to Reactor Water Cleanup, Reactor Building Ventilation, Containment Atmosphere Dilution. Torus Vent and Purge, Drywall Floor and Equipment Drain Sumps, Drywall Containment Atmospheric Monitors, Recirculation System Sample Lines, Traversing In-Core Probes, LPCI Inboard Injection Valves, Residual Heat Removal Drain to Radwaste, and auto initiation of Standby Gas Treatment. (Note that two Reactor Water Cleanup PCIS valves did not close due to their respective circuit breakers being in the open position for planned maintenance activities.) The above event meets the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) for RPS actuation while the reactor was critical, as well as 10 CFR 50.72(b)(3)(iv)(A) for the valid actuation of systems listed in 10 CFR 50.72(b)(3)(iv)(B), including general containment isolation signals affecting containment isolation valves in more than one system, the HPCI system, and the RCIC system. The NRC Resident Inspector has been briefed. |
| Where | |
|---|---|
Fitzpatrick  New York (NRC Region 1) | |
| 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:+-1.42 h-0.0592 days <br />-0.00845 weeks <br />-0.00195 months <br />) | |
| Opened: | Dan Johnson 04:48 Sep 14, 2005 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Sep 14, 2005 |
| 41987 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Shutdown (0 %) |
FitzPatrick with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 563732023-02-19T06:05:00019 February 2023 06:05:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation ENS 561192022-09-26T07:06:00026 September 2022 07:06:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram ENS 545032020-01-31T10:55:00031 January 2020 10:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram Due to Main Turbine Trip ENS 520422016-06-24T16:15:00024 June 2016 16:15:00 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 Reactor Recirculation Pumps Degradation ENS 516802016-01-24T03:41:00024 January 2016 03:41:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Scram Due to Lowering Intake Level ENS 486762013-01-16T02:12:00016 January 2013 02:12:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of a 4160 Volt Bus While Performing Testing ENS 485012012-11-11T08:55:00011 November 2012 08:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Reactor Scram Due to Turbine Trip Followed by Unusual Event Declared Due to Main Transformer and Bus Duct Fire ENS 484792012-11-05T02:53:0005 November 2012 02:53:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram from Full Power Following Turbine Trip ENS 483862012-10-05T17:03:0005 October 2012 17:03:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Rps and Pciv Actuation Due to Loss of Offsite Power ENS 445462008-10-07T10:35:0007 October 2008 10:35:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation Due to Loss of Power During Testing ENS 437522007-10-28T04:59:00028 October 2007 04:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Scram Due to Lowering Intake Level ENS 436352007-09-12T10:35:00012 September 2007 10:35:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Following Intake Structure Traveling Screen Fouling ENS 419872005-09-14T06:13:00014 September 2005 06:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram on Low Reactor Vessel Water Level During Planned Maintenance ENS 400722003-08-14T20:26:00014 August 2003 20:26:00 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 a Loss of Offsite Power. 2023-02-19T06:05:00 | |