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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 49195 | 28 May 2013 17:39:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 Day Report - Invalid Actuation of Specified System | This 60-day optional report as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10 CFR 50.73 (a)(2)(iv)(A) to describe an invalid actuation of a specified system, specifically the Nuclear Service Water (RN) system. This event had no impact on public health and safety. During work to replace a timer associated with an RN (Nuclear Service Water) level circuit, electrical adapters and jumpers were installed incorrectly, resulting in generation of an Emergency Low Pit Level signal. This resulted in an unplanned actuation for RN to realign its suction source from Lake Wylie (normal source) to the alternate source, the SNSWP (Standby Nuclear Service Water Pond). On 5/28/13, with both units at 100% power, a lo-lo level signal was received for A Train RN Pit, initiating the realignment to the SNSWP for both A and B trains. Prior to this event, both trains of RN were aligned to the SNSWP for maintenance. The lo-lo level signal did initiate a start of all available RN Pumps. Associated valves, including RN crossover valve, return header isolation valves and non-essential header isolation valves closed as expected. This separated RN trains A and B. This was a complete actuation for Train A and the system performed as designed for existing plant conditions. This event was entered into the site corrective action program for resolution. The licensee will notify the NRC Resident Inspector, as well as, the State and local governments. | Service water | |
| ENS 48706 | 22 December 2012 06:42:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 Day Report - Invalid Actuation of the Afw System | This 60-day optional report as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a specified system, specifically the Auxiliary Feedwater (AFW) system. On December 22, 2012 at 0142, with Unit 1 in Mode 4, the 1A AFW pump automatically started due to failure to reset the signal created when the 1B Feedwater Pump was tripped for testing. The 1A feedwater pump was already in the 'tripped' condition when the 1B feedwater pump was tripped, resulting in an auto start signal being generated for the AFW system. Both trains of the AFW had the auto start defeat instated at the time of the testing of the 1B Feedwater pump, blocking the start signal. During subsequent alignment of the AFW for standby readiness, the auto start defeat was removed from the 1A AFW system without resetting the system to remove the signal generated during the 1B Feedwater pump testing, resulting in the actuation of the system. The 1B Feedwater Pump had been reset and was in service therefore the signal associated with the trip of both feedwater pumps was not consistent with the actual plant conditions at the time that the auto start defeat was removed from the 1A AFW system. Following the auto start of the 1A motor driven AFW pump, operators confirmed the 1A AFW train experienced a complete actuation and that the 1A AFW Pump and its associated valves functioned as designed. The pump was subsequently secured and the AFW system was returned to standby readiness. This event was entered into the site specific correction action program for resolution. The NRC Resident Inspector has been informed. The licensee will notify the states of North Carolina and South Carolina. Additionally the licensee will notify York, Gaston, and Mecklenburg County. | Feedwater Auxiliary Feedwater | 05000414/LER-2015-001 |
| ENS 44352 | 9 June 2008 20:31:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 Day Report - Invalid Actuation of Main Steam Isolation System | This 60-day optional report, as allowed by 10 CFR 50.73 (a)(1), is being made under the reporting requirement in 10 CFR 50.73 (a)(2)(iv)(A) to describe an invalid actuation of a specified system, specifically the Main Steam (SM) System. On June 9, 2008, at 1631 with Unit 1 in Mode 5, an invalid signal was generated on Train B of the SM system during Engineered Safety Features testing. During the performance of returning the Solid State Protection System (SSPS) to 'normal', the SSPSB mode selector switch was placed to operate. A Unit 1 Feedwater and Main Steam isolation occurred. Part of the 'return to normal' sequence is to place the SSPS Input Error Inhibit switch to the inhibit position. The technician failed to insure the inhibit switch 'snapped' into position and trip signals were generated when the Output Test relay switch was placed to Operate. The SM system was returned to standby readiness. This was considered a partial system/train actuation. During this event, the SM system performed as expected. This event was entered into the site specific corrective action program for resolution. The licensee has notified the NRC Resident Inspector, and will be notifying the State, local and other government agencies. | Feedwater Main Steam | |
| ENS 44051 | 24 January 2008 07:35:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 Day Report - Invalid Actuation of the Nuclear Service Water System | This 60-day optional report as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10 CFR 50.73 (a)(2)(iv)(A) to describe an invalid actuation of a specified system, specifically the Nuclear Service Water System (NSWS). While performing changeout of a Nuclear Service Water (RN) current module, there was an unexpected auto swap from the normal heat sink (Lake Wylie) to the ultimate heat sink (Standby Nuclear Service Water Pond (SNSWP)) occurred and the system responded as designed. Work was stopped when notified by Operations. This event occurred when technicians attempted to isolate power to the module prior to replacing. Unable to do so, they decided to perform a changeout under hot conditions. While tracing power utilizing wire tabs, the technicians did not identify that removing wire from terminal 12 of the module disturbs the power path to other channels. The channel associated with the bad module remained in the trip condition throughout, and when power to other channels was disturbed, the logic for a swap from the normal heat sink to the ultimate heat sink was completed and the automatic swap occurred as designed. This event was entered into the site corrective action program for evaluation. The licensee will inform local and state agencies and has informed the NRC Resident Inspector. | Service water | |
| ENS 42873 | 8 August 2006 20:17:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 Day Report - Invalid Actuation of Auxiliary Feed Pump 2B | This 60-day report as allowed by 10 CFR 50.73 (a)(2)(iv)(A) to describe an invalid actuation of a specified system, specifically the Auxiliary Feedwater System (AFW). This event involved an invalid actuation of the Motor Driven Auxiliary Feedwater pump 2B during routine Unit 2 Auxiliary Safeguards Testing on 8/8/06. The system was properly aligned and did inject water into Steam Generators 2C and 2D as designed to perform a complete actuation of AFW pump 2B. The motor driven auxiliary feedwater pumps will automatically start and provide the minimum required feedwater flow within one minute following any of these conditions: 1. Two out of four low-low level alarms in any one of the four steam generators. 2. Loss of both main feedwater pumps 3. Initiation of safety injection signal 4. Loss of station normal auxiliary electric power 5. AMSAC signal Since none of the five auto-start parameters were met at the time of the system actuation the signal was determined to be invalid. Engineering reviewed the CA Pump Start circuit to determine which equipment failures could cause the switchgear breaker for the AFW Pump 2B to close and start the pump. These included reviewing sequencer start signals, manual pushbuttons, and associated contacts and breakers. The failure of the fluke meter used during the testing was considered, also. In addition, the Operations Test Group performed an analysis of the human performance aspects of this testing. Based on these investigations potential equipment failures have been ruled out and based on the correspondence in time with when the inadvertent start occurred and when the meter reading was taken, it is believed that the inadvertent start is due to an anomaly with the Fluke 189 meter or issues when taking the measurement. The measurement is taken across an energized circuit, which can be susceptible to inadvertent actuations. The test procedure has been revised to open links on the circuit to prevent inadvertent operation. The licensee notified the NRC Resident Inspector. | Steam Generator Feedwater Auxiliary Feedwater | |
| ENS 41132 | 22 August 2004 08:50:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 Day Report - Invalid Actuation of Specified System | This 60-day optional report as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a specified system, specifically the Nuclear Service Water System (NSWS). During TSM 158 work associated with W/O 98686671 a SPOC Relief Supervisor inadvertently caused a ground when disconnecting test meter leads from an energized circuit. This ground resulted in an unplanned RN (Nuclear Service Water) swap to the SNSWP (Standby Nuclear Service Water System). At 0450 on 8/22/04, a lo-lo level signal was received for B Train RN Pit and this initiated a swap to the SNSWP for both A and B trains. Prior to this event, both trains of RN had been aligned to the SNSWP on 8/16/04 for maintenance, and remained on the SNSWP due to 1RN-4B degraded condition (PIP C-04-3937) The lo-lo level signal did initiate a start of all four RN Pumps (1B and 2B started; 1A and 2A were already operating). RN crossover valves 1RN-53B and 1RN 54A closed as expected, separating RN trains A and B. Flow was manually initiated through all four NS Heat Exchangers to attempt to meet RN pump minimum flow demands. This was a complete actuation for Train B and the system performed as designed for existing plant conditions. This event was entered into the site corrective action program for resolution (PIP C04-04056). At 1629 on 8/22/04, a lo-lo level signal was received for B Train RN Pit and this initiated a swap to the SNSWP for both A and B trains. Prior to this event, both trains of RN had been aligned to the SNSWP on 8/16/04 for maintenance, and remained on the SNSWP due to 1RN-4B degraded condition (PIP C-04-3937). RN system response was as expected. The lo-lo level signal did initiate a start of all four RN Pumps (1B and 2A started; 1A and 2B were already operating). RN crossover valves 1RN-47A and 2RN-47A closed as expected, and return header isolation valves 1RN-53B and 1RN-54A closed as expected, separating RN trains A and B. Flow was manually initiated through all four NS heat exchangers to attempt to meet RN pump minimum flow demands. The reasons for the inadvertent actuation was a blown fuse. Performed Troubleshooting Plan to I/R Cause of Fuse HA-1 in 1EATC6 blowing under W/O #98686856-01 and 03. No cause for the fuse blowing on 2004-08-22 could be found. All data obtained under the plan were well within normal values. Thermography data indicate the fuse temperature was about 3 Deg F above ambient. The current through the fuse is 1.3 Amps. (Fuse HA-1 is a FLQ-3) Current alarm HF in 1EATC6 was calibrated, and was found in tolerance. No change in current through the fuse was noted during the calibration of the current alarm. The current alarm was cycled 5 times. This was a complete actuation for Train B and the system performed as designed for the existing plant conditions. This event has been entered into the site specific corrective action program for resolution. (C04-4060). The licensee notified the NRC Resident Inspector. | Service water |