ENS 41584
ENS Event | |
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10:00 Apr 10, 2005 | |
Title | |
Event Description | Nine Mile Point Unit 1 received a valid RPS SCRAM signal from high water level in the SCRAM Dump Volume (SDV). While restoring the Hydraulic Control Rod Unit (HCU) for control rod 02-35 to service, the internals to the plug valve for the Instrument Air Supply (116 Valve) to the SCRAM Inlet and Outlet valves failed. This failure caused an approximate 1/2" hole in the SCRAM Air Header, which resulted in the SCRAM Air Header pressure lowering rapidly due to the leak.
Operators at the HCU recommended isolating the SCRAM Air Header. The Shift Manager was contacted by the job supervisor and received permission to isolate the SCRAM Air Header. SCRAM inlet and outlet valves opened, SDV vents and drains closed due to the loss of SCRAM Air Header pressure. Approximately 3 minutes after SCRAM Air Header depressurization, a full SCRAM signal occurred as expected due to the water level in the SDV. There was no fuel in the Reactor Vessel (RPV). No Control Rod motion occurred due to all Control Rods being inserted or isolated for maintenance. Immediate (8 Hour Non-Emergency) notification of this event being made as a result of the requirements of 10CRF50.72(b)3(iv)(A). The licensee stated that more information on the event can be found in Nine Mile Point Internal document DER - NM-2005-1565. The license will be notifying the NRC Resident Inspector.
The scram event that occurred on April 10, 2005 was not initiated from a "valid" scram initiation signal (i.e., none of the instrumentation signals identified in Technical Specification Table 3.6.2a triggered the scram). To the contrary, a valve on a CRD hydraulic control unit (HCU) failed and Operations took action to isolate instrument air from the scram air header. This operator action had the identical effect that a scram signal would have had - the scram air header completely vented through the broken valve and caused the scram inlet and outlet valves on the HCUs to open and the scram discharge volume vents and drains to close. At the time, the reactor was defueled and all control rods were either already inserted or properly removed from service for maintenance, thus, the event did not result in any control rod movement (i.e., the system had been properly removed from service and the safety function had already been performed). Subsequent to the initiating event, as per the design of the CRD and RPS systems, the scram discharge volume filled and a full RPS scram signal was generated. Conclusion: The scram event that occurred on April 10, 2005, resulted from an invalid scram initiation signal. At the time, the reactor was defueled, the CRD system had been properly removed from service and the safety function had been properly performed (no control rods moved). Thus, pursuant to the guidance in NUREG-1022, it is appropriate to conclude that the event is not reportable under 10CFR50.72(b)(2)(iv) or 10CFR50.73(a)(2)(iv). As such, the 8-hour ENS notification that was made at 11:46 on 4/10/05 (reference Event Number #41584) is being retracted The licensee notified the NRC Resident Inspector. R1DO (Bellamy) was contacted. |
Where | |
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Nine Mile Point New York (NRC Region 1) | |
Reporting | |
10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
Time - Person (Reporting Time:+1.77 h0.0738 days <br />0.0105 weeks <br />0.00242 months <br />) | |
Opened: | Quentin Hicks 11:46 Apr 10, 2005 |
NRC Officer: | Bill Huffman |
Last Updated: | May 19, 2005 |
41584 - NRC Website | |
WEEKMONTHYEARENS 570042024-03-04T00:42:0004 March 2024 00:42:00
[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 Scram Due to Main Turbine Trip on LOW Condenser Vacuum ENS 567102023-09-02T10:32:0002 September 2023 10:32:00 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 Automatic Reactor Scram Due to Feedwater Transient ENS 560892022-09-04T20:39:0004 September 2022 20:39:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Activation ENS 558212022-04-05T06:23:0005 April 2022 06:23:00 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 Scram on LOW Level ENS 540352019-04-29T20:33:00029 April 2019 20:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Power Oscillations and High Pressure Coolant Injection System Initiation ENS 539982019-04-14T04:03:00014 April 2019 04:03:00 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 Specified System Actuation ENS 533952018-05-10T06:48:00010 May 2018 06:48:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Emergency Diesel Start on Partial Loss of Offsite Power ENS 529502017-09-06T15:57:0006 September 2017 15:57:00 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 ENS 524252016-12-10T13:48:00010 December 2016 13:48:00 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 High Main Turbine Vibrations ENS 513692015-09-04T13:16:0004 September 2015 13:16:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Automatic Scram and Specified System Actuations Due to Msiv Closure ENS 498322014-02-16T17:16:00016 February 2014 17:16:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Unit 2 Experienced a Partial Loss of Offsite Power with Autostart of Division I and III Edgs ENS 485902012-12-13T21:30:00013 December 2012 21:30:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Primary Containment System Declared Inoperable ENS 484812012-11-06T05:06:0006 November 2012 05:06:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation High Pressure Coolant Injection Actuation Signal ENS 484772012-11-03T12:23:0003 November 2012 12:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram on Low Reactor Water Level ENS 484562012-10-30T01:00:00030 October 2012 01:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Initiation of Emergency Diesel Generator Due to Loss of One Off-Site Power Source ENS 484532012-10-29T04:00:00029 October 2012 04:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Actuation While Critical Due to Generator Load Reject ENS 483232012-09-20T13:23:00020 September 2012 13:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram and High Pressure Coolant Injection System Initiation ENS 481102012-07-17T15:18:00017 July 2012 15:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to High Neutron Flux ENS 468082011-05-03T00:51:0003 May 2011 00:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram ENS 464092010-11-10T15:56:00010 November 2010 15:56:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Automatic Scram and High Pressure Coolant Injection System Initiation During Testing ENS 454122009-10-05T15:58:0005 October 2009 15:58:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Scram and High Pressure Coolant Injection Following a Loss of Feedwater Level Control ENS 449822009-04-10T09:38:00010 April 2009 09:38:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation High Pressure Coolant Injection Automatic Initiation Due to Turbine Trip ENS 449232009-03-21T05:21:00021 March 2009 05:21:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation High Pressure Coolant Injection System Initiation Following Planned Manual Scram ENS 445982008-10-24T01:26:00024 October 2008 01:26:00 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 Loss of the Electronic Pressure Regulator ENS 442062008-05-13T12:25:00013 May 2008 12:25:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 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 Loss of Offsite Power ENS 426332006-06-12T17:02:00012 June 2006 17:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Hpci Inititation Signal Due to Turbine Trip Signal During Startup ENS 419272005-08-18T13:49:00018 August 2005 13:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram Due to Loss of a Power Board ENS 415842005-04-10T10:00:00010 April 2005 10:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Scram Signal Resulting from Failure of a Supply Valve to the Scram Air Header ENS 409982004-08-30T12:35:00030 August 2004 12:35:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 1 Manually Scrammed Due to Oscillating Reactor Vessel Water Level ENS 407192004-05-02T06:17:0002 May 2004 06:17:00 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)(i), Tech Spec Required Shutdown Manual Scram Due to Rising Torus Temperature Due to Stuck Open Erv ENS 406842004-04-18T22:30:00018 April 2004 22:30:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Residual Heat Removal System Isolation Due to a Rise in Reactor Pressure ENS 403222003-11-14T02:49:00014 November 2003 02:49:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of 115 Kv Line Results in Emergency Diesel Generator Auto-Start 2024-03-04T00:42:00 | |