ENS 47533
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ENS Event | |
|---|---|
15:30 Dec 18, 2011 | |
| Title | Loss of Rhr Cooling Due to Incorrect Reactor Water Level Indication |
| Event Description | On 12/18/11 at approximately 0930 CST, with the plant in Mode 4, while Operations was lowering reactor water level as part of restoration activities following the Reactor Pressure Vessel hydrostatic test, an automatic reactor scram and Residual Heat Removal (RHR) 'A' pump trip occurred due to a valid Reactor Water Level Low (Level 3) signal. The cause of the low level appears to be due a significant disparity between the Upset and Shutdown Range level instrumentation and the Level 3 RPS [Reactor Protection System] instrumentation. No rod motion occurred during the reactor scram as all control rods were fully inserted at the time of the event. Operations immediately entered the station off-normal procedures for Loss of Shutdown Cooling and Reactor Scram. The 'A' RHR pump was restored at 0956 CST. Reactor coolant temperature increased from approximately 128.7 deg F to 131.7 deg F during the event. At 1112 CST, the scram was reset and at 1216 CST, the off-normal procedures were exited.
Following the event as part of trouble shooting, maintenance personnel performed a fill and vent of reactor water level transmitter, 1B21N027. At the completion of this fill and vent, indicated water level changed from 195" to 86" on Shutdown Range and from off-scale high (>180") to 103"on Upset Range. No change in other reactor water level indication was observed. This event is reportable under 10 CFR 50.72 (b)(3)(v)(B), as an event or condition that could have prevented the fulfillment of a safety function needed to remove residual heat, and 10 CFR 50.72 (b)(3)(iv)(A), event or condition that results in a valid actuation of the reactor protection system (RPS). The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Clinton  Illinois (NRC Region 3) | |
| 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: | 05000461/LER-2011-008 |
| Time - Person (Reporting Time:+2.63 h0.11 days <br />0.0157 weeks <br />0.0036 months <br />) | |
| Opened: | Dale Shelton 18:08 Dec 18, 2011 |
| NRC Officer: | Charles Teal |
| Last Updated: | Dec 18, 2011 |
| 47533 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | A |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
Clinton 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 541972019-08-03T07:26:0003 August 2019 07:26:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge En Revision Imported Date 8/7/2019 ENS 536232018-09-26T05:00:00026 September 2018 05:00:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Undervoltage Condition Initiates an Automatic Start of the Diesel Generator ENS 482692012-09-03T03:04:0003 September 2012 03:04:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Transfer of Emergency Reserve Auxiliary Transformer Isolating Fuel Pool Cooling and Cleanup System, and Fuel Building Ventilation System ENS 475332011-12-18T15:30:00018 December 2011 15:30:00 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 Loss of Rhr Cooling Due to Incorrect Reactor Water Level Indication ENS 467712011-04-20T14:15:00020 April 2011 14:15:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Watertight Doors Left Ajar Simultaneously During Room Checks ENS 421612005-11-21T16:42:00021 November 2005 16:42:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat Division 3 Emergency Diesel Generator Declared Inoperable ENS 408692004-07-14T05:45:00014 July 2004 05:45:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps and Containment Isolation Actuation Due to Low Rpv Level ENS 403682003-12-02T22:58:0002 December 2003 22:58:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Scram Due to Low Reactor Water Feed Pump Suction Pressure 2019-08-03T07:26:00 | |
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