ENS 43635
ENS Event | |
|---|---|
10:35 Sep 12, 2007 | |
| Title | Reactor Scram Following Intake Structure Traveling Screen Fouling |
| Event Description | As a result of high winds and a severe storm front moving through the area a Nuclear Plant Operator (NPO) found the intake canal water murky, wind speed was noted to be 40 MPH. The Traveling Screens were placed in the continuous mode of operation and increased monitoring was put in effect. At 0520 the NPO noted that 'a lot of weeds and fish were coming in through the intake' and that a full trash basket had been changed out. At approximately 0630 the NPO reported that the traveling screens were not moving and intake level was lowering due to the influx of debris. The Shift Nuclear Operator (SNO) entered the appropriate Abnormal Operating Procedure (AOP) for lowering intake level and commenced rapid power reduction. At 0635 with intake level at 240 feet the SNO inserted a manual scram and entered the appropriate AOP and Emergency Operating Procedure (EOP).
Reactor Vessel level decreased to less than 177 inches above the top of active fuel resulting in a Primary Containment Isolation System (PCIS) Group 2 isolation signal. The PCIS Group 2 isolation resulted in a valid signal to close PCIS valves in the Drywell Floor Drain System, the Drywell Equipment Drain System, the Residual Heat Removal (RHR) System, the Traversing In-Core Probe (TIP) System, the Containment Atmosphere Dilution (CAD) System, and the Reactor Water Clean-Up (RWCU) System. However, as a result of the power reduction the operators were able to maintain reactor vessel level above the actuation setpoint for the High Pressure Coolant Injection (HPCI) System and the Reactor Core Isolation Cooling (RCIC) Systems and these systems were not required to operate. At 0640 the Scram was reset, at 0710 the Group 2 PCIS Isolation was verified, and at 0729 the Group 2 PCIS Isolation was reset. The cause of the traveling screens stopping has been determined to be due to shear pins on the traveling water screen shearing due to excessive debris loading. All equipment responded as expected during the downpower and subsequent manual Scram. All rods are in and the plant is stable in MODE 3, Hot Shutdown." Decay heat is being removed by dumping steam to the condenser via the turbine bypass valves. The safety buses are being powered by offsite power. The 'B' train Residual Heat Removal pump was out of service at the time of the event for planned maintenance. The licensee notified the NRC Resident Inspector.
At 1034 with the plant shutdown and a cooldown in progress reactor vessel (RV) level lowered to less than 177 inches above TAF [Top of Active Fuel]. This resulted in a valid Reactor Protection System (RPS) Scram signal and a PCIS Group 2 Isolation Signal. AP systems responded as expected. Reactor vessel level remained above the actuation setpoint for HPCI and RCIC and they were not required to operate. RV level was restored and the Scram was reset. At the time of the initial event and at this update the plant is in LCO action statement 3.5.1.A for the 'B' RHR Pump being out of service. The system is being restored at this time. The licensee notified the NRC Resident Inspector. The licensee also notified the state and is providing a press release to the media. Notified R1DO (Trapp). |
| 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 | |
| LER: | 05000333/LER-2007-002 |
| Time - Person (Reporting Time:+-0.62 h-0.0258 days <br />-0.00369 weeks <br />-8.49276e-4 months <br />) | |
| Opened: | Eugene Dorman 09:58 Sep 12, 2007 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Sep 12, 2007 |
| 43635 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | Yes, Manual Scram |
| 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 | |