Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56896 | 18 December 2023 07:23:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection System Inoperable | The following information was provided by the licensee email: At 0223 EST, on 12/18/2023, while Unit 2 was at 100 percent power in mode 1, the high pressure coolant injection (HPCI) outboard steam isolation valve closed resulting in the HPCI system being declared inoperable. The cause of the outboard steam isolation valve closing is under investigation. HPCI does not have a redundant system, therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). The safety function was restored at 0512, on 12/18/23, and HPCI has been declared operable. Reactor core isolation cooling (RCIC) and low pressure emergency core cooling systems (ECCS) were operable during this time. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | High Pressure Coolant Injection Reactor Core Isolation Cooling Emergency Core Cooling System | |
| ENS 55448 | 8 September 2021 05:59:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Unit 1 High Pressure Coolant Injection (HPCI) System Inoperable | At 0159 EDT on 09/08/2021, the HPCI pump discharge valve failed to reopen during a valve surveillance, resulting in the HPCI system being declared INOPERABLE. HPCI does not have a redundant system; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). Reactor Core Isolation Cooling system and low pressure Emergency Core Cooling Systems were OPERABLE during this time. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | High Pressure Coolant Injection Reactor Core Isolation Cooling Emergency Core Cooling System | |
| ENS 54677 | 22 April 2020 14:15:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection System (Hpci) Inoperable | At 1015 (EDT), on 04/22/2020, while Unit 2 was at approximately 0.4 percent power in MODE 2, reactor pressure was increased to 150 psig while HPCI was INOPERABLE due to not having been placed in standby. HPCI does not have a redundant system; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). ADS (Automatic Depressurization System) and low pressure ECCS (Emergency Core Cooling System) systems were OPERABLE during this time. HPCI was returned to OPERABLE status at 1109 hrs. on 04/22/2020. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | High Pressure Coolant Injection | |
| ENS 54237 | 23 August 2019 02:34:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection (Hpci) System Inoperable | At 2234 (EDT), on 08/22/2019, while Unit (2) was at approximately 100 percent power in MODE 1, it was discovered that Unit 2 HPCI was INOPERABLE. HPCI does not have a redundant system; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Initial evaluation is that it is a power supply issue. The system had no indications, followed by smoke from behind the circuitry, and then indications returning. This is associated with a 14-day Limiting Condition for Operation. | High Pressure Coolant Injection | |
| ENS 53944 | 19 March 2019 05:40:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection System Inoperable | At 0140 (EDT) on 03/19/2019, while the unit was at approximately 1% power and 154 psig pressure in MODE 2, it was discovered that Unit 2 High Pressure Coolant Injection (HPCI) was INOPERABLE. HPCI does not have a redundant system, therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Unit 2 entered LCO 3.5.1.c for the HPCI being inoperable. There is no effect on Unit 1. | High Pressure Coolant Injection | |
| ENS 52543 | 8 February 2017 16:51:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection System Inoperable Due to Degraded Dc to Ac Inverter | During a control room panel walk down by an on-shift Reactor Operator at approximately 1151 (EST) on 2/8/2017, Unit 1 High Pressure Coolant Injection (HPCI) suction and discharge pressure indicators were noted to be downscale. I & C investigated and found the output of 1E41K603, DC to AC inverter, degraded. This inverter also powers the HPCI flow controller. Without the flow controller HPCI would not auto-start to mitigate the consequences of an accident, thus HPCI was declared inoperable. All other emergency core cooling systems and the Reactor Core Isolation Cooling (RCIC) system remain operable. HPCI is a single train system with no redundant equipment in the same system, thus this failure is reportable as an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident, 10CFR50.72(b)(3)(v)(D). Inverter 1E41K603 was replaced and functionally tested satisfactorily at 1630 on 2/8/2017, restoring HPCI to operable status. The NRC Resident Inspector was notified. | High Pressure Coolant Injection Reactor Core Isolation Cooling Emergency Core Cooling System | |
| ENS 50080 | 2 May 2014 00:45:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Loss of Hpci Operability Due to Water Accumulation in the Hpci Turbine | While investigating a Unit 1 high pressure coolant injection (HPCI) room instrument sump level high alarm, condensation was observed dripping out around the HPCI turbine shaft gland seals. A steady stream of water was also observed coming out of the governor end gland seal along with a slight leak coming from the coupling end. Observation revealed that leakage through the 'closed' steam admission valve (1E41-F001) was apparently resulting in water accumulation in the HPCI turbine. A blown fuse that prevented the associated HPCI exhaust drain pot from draining in conjunction with the leakage by the steam admission valve was determined to be sufficient to impact HPCI operability. Required actions were taken in accordance with the Technical Specifications. Efforts are underway to determine the actions needed to restore the HPCI system to operable status. The licensee has notified the NRC Resident Inspector.
HPCI has been restored to an Operable but degraded nonconforming condition. Fuses replaced and automatic functions restored. Leakage confirmed to not be excessive for this condition. Compensatory actions established. Restoration time 2345 EDT 5/1/14. The licensee will notify the NRC Resident Inspector. Notified R2DO (Ayers). | High Pressure Coolant Injection | |
| ENS 48827 | 18 March 2013 13:10:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection Inoperable Following Refueling Outage | On 3/18/2013, with the Unit 2 reactor at approximately 165 psig while in Mode 2 (Startup) following a refueling outage, the high pressure coolant injection (HPCI) system was undergoing post-maintenance testing to demonstrate operability of the system following the performance of major system maintenance. The provision allowed by the Technical Specifications was being used to increase reactor pressure above 150 psig for the purpose of performing operability testing and there was reasonable assurance that the HPCI system had been restored to support successful test results. (However, the HPCI system failed to pass operability testing and) as a result of the inability of the HPCI system to function as required during this testing while above 150 psig, HPCI was not capable of performing its safety function. Reactor pressure was decreased below the Technical Specification 3.5.1 LCO Applicability Requirement of 150 psig and work is in progress to make the needed repairs to support returning HPCI to an operable condition. The licensee notified the NRC Resident Inspector. | High Pressure Coolant Injection | |
| ENS 45541 | 5 December 2009 15:59:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpci Out of Service Due to the Loss of the Suction Auto-Swap Function | On 12-04-09 at 16:00, condensate storage tank (CST) level switch (2E41 N002), was declared inoperable due to not actuating at the correct set point. A RAS (Required Action Statement) was entered to align high pressure coolant injection (HPCI) suction to the suppression pool within 24 hours as required by Tech Spec (Technical Specification) action statement 3.3.5.1.D 2.2. The switch was found stuck and was freed up after manual manipulation and tripped correctly during a functional test. It was decided on 12-05-09 to perform a calibration on the level switch prior to declaring it operable. During performance of calibration procedure 57CP-CAL-012-2 at 1059 EST on 12-05-09, a jumper was installed that rendered the HPCI and reactor core isolation cooling (RCIC) auto-transfer suction swap from CST to suppression pool inoperable. This is a loss of function for the initiation capability of HPCI and RCIC CST low level suction swap instrumentation. This loss of function was not discovered until 1330 on 12-05-09, at which time TS (Technical Specification) 3.3.5.1.D was entered for HPCI and TS 3.3.5.2.D for RCIC, until HPCI and RCIC suction were manually aligned to the suppression pool which allowed the plant to exit the required actions to declare HPCI and RCIC inoperable within 1 Hour. HPCI and RCIC were aligned to the suppression pool at 1341 EST. The RCIC suction was realigned to the suppression pool as required by the Tech Specs in order to restore its operability. It should be noted that no credit is taken for RCIC in the safety analysis nor is this system considered an ESF system. For this reason there are no reporting requirements associated with the inoperability of RCIC. HPCI was declared inoperable in accordance with the instrumentation Tech Specs, but during this time frame HPCI was capable of performing its safety function. However- additional review will be needed to confirm that HPCI could have operated for the duration of its mission time of 4 hours while aligned to the condensate storage tank. Absent that information this report is being made due to HPCI being declared inoperable until its suction was realigned to the suppression pool. This assumed loss of function for HPCI is being reported in accordance with 10CFR50.72(b)(3)(v)(D) since a final determination has not been made that HPCI would have continued to perform its safety function for the required mission time while aligned to the CST. The licensee notified the NRC Resident Inspector. | High Pressure Coolant Injection Reactor Core Isolation Cooling | |
| ENS 44849 | 12 February 2009 17:30:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection Suction Source Instrument Malfunction | Unit 2 HPCI (High Pressure Coolant Injection) system is being considered inoperable due to the following information: (Condition Report 2009101257) The instrumentation associated with the automatic suction swap for Unit 2 HPCI was reviewed as a result of CR 2009100480 to confirm the set points that determine the condensate storage tank (CST) level at which the suction swap would occur. During the course of this review, the corporate design engineer contacted the level switch vendor to review the configuration of the level switches and to confirm the expected operation of the switches (2E41-N002 & 2E41-N003) given their configuration. Based on the configuration of the instrument lines and physical location of the level switches, the vendor reported that either liquid or gas would most likely be entrapped in the external cage of the Magnetrol level switches. This would prevent the instruments from performing their automatic swap function. Based on this information the 'as found' condition of the switches indicate that this condition has been present since the installation of the switches when implementing the DCP in 1991 which affects the operability of this instrumentation. Even though the suction swap instrumentation on low CST level is considered inoperable, there is no apparent actual adverse impact on nuclear safety. However, the instrumentation is included in the Technical Specifications and its inoperability would make HPCI inoperable if it is aligned to the CST rather than being aligned to the suppression pool. The normal system alignment is with its suction source to the CST, therefore HPCI is being considered as inoperable. Until the configuration of the level switches has been addressed, these Magnetrol level switches must be considered inoperable, the appropriate Technical Specification RAS (Required Action Statement) will be entered and the suction source for HPCI should be aligned to the suppression pool when HPCI is required to be operable. This condition only applies to Unit 2. The licensee has notified the NRC Resident Inspector.
Event Report 44849 Retraction: On February 12, 2009, a condition was discovered where the physical location of level switches relied upon for automatically transferring the suction of the Unit 2 high pressure coolant injection (HPCI) system from the condensate storage tank (CST) to the suppression pool on low CST level did not meet the setpoints given in the Technical Specifications. Based on the information available at that time HPCI would have to be considered inoperable based on the fact that the affected instrumentation was inoperable and with HPCI aligned to the CST. Since the unit was shutdown HPCI was not required to be operable. After further review the determination has been made that at the time of discovery the 'as found' plant configuration associated with the suction swap setpoint for the Unit 2 high pressure coolant injection (HPCI) system could NOT have prevented the fulfillment of the safety function since the unit was in Cold Shutdown, and HPCI was not required to be operable. Based on this information this condition did not require an NRC notification in accordance with I0CFR50.72 and as such is being retracted through this update response. The condition will be reported in accordance with I0CFR50.73(a)(2)(v), The licensee has notified the NRC Resident Inspector. Notified R2DO (Sykes) | High Pressure Coolant Injection | |
| ENS 43884 | 6 January 2008 16:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpci Declared Inoperable Due to Failed Surveillance Test | During HPCI pump operability surveillance in preparation for a system outage, the system failed to achieve rated flow and pressure in the time required by procedure and Tech Specs. The procedural requirement is <49 seconds and the Tech Spec requirement is < 50 seconds. The system achieved rated flow and pressure in 54 seconds. The system outage has been delayed until troubleshooting plans can be developed and implemented. The licensee notified the NRC Resident Inspector.
The initial notification was made as a result of the failure of HPCI to meet its response time of 50 seconds as defined in the Technical Requirements Manual (TRM) due to a degraded component. Failure to meet the operability procedure requirements resulted in the high pressure coolant injection (HPCI) system being considered inoperable. Since HPCl is a single train system, its inoperability was the event that warranted a notification to meet the following reporting requirement: 10 CFR 50.72(b)(1)(v) Any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems needed to: (D) Mitigate the consequences of an accident. An additional review and evaluation of the licensing basis was performed and demonstrated that the procedural required response time was set conservatively. As expected, the licensing basis does not require or assume any specific start time and HPCl is not credited in the accident analyses. The acceptance criterion contained in the TRM is within licensee control via the 10 CFR 50.59 process. Consequently, the TRM criterion was revised to 75 seconds to retain a value to assure continued monitoring and trending of HPCl performance in order to recognize and prevent continued performance degradation. Additionally, it is reasonable to conclude that HPCl would have completed its mission time of 4 hours despite the degraded condition of the EGR (Electronic Governor Remote) that caused the initial slower response time. This is based on the fact that HPCl started and ran at rated flow and pressure for approximately 39 minutes prior to shutdown with no problems identified. This removes any questions regarding its ability to restart and run based on demand during its mission time of 4 hours. An industry expert on this system and the engineer from the vendor that supports this system concurred with that conclusion. Since this subsequent review and evaluation determined that the slower response time did not render HPCl inoperable, no single train failure of HPCl occurred. The system was fully capable of performing its intended safety functions during the event timeline. Based on this information this notification serves to retract notification # 43884 made on 1/06/08. The licensee notified the Resident Inspector of this retraction. Notified the R2DO (Musser). | High Pressure Coolant Injection | |
| ENS 43374 | 18 May 2007 21:45:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Inoperable Hpci Pump | While investigating an oil leak on the HPCI oil piping, the reservoir level was determined to be higher than expected. Further investigation led to the discovery of water in the HPCI oil system. The quantity of water in the oil was sufficient to impede normal HPCI operation. Therefore, HPCI was declared inoperable. The licensee noticed an oil leak while conducting routine plant rounds. When the operator investigated the oil leak further, he noticed the oil level in the reservoir was higher than expected. The licensee is investigating the source of the water but they believe the seal leak-off line may be clogged. The licensee plans to drain down, flush the system, refill and run the pump for operability determination by the afternoon of 5/19/07. The licensee will notify the NRC Resident Inspector. | ||
| ENS 43242 | 15 March 2007 19:32:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpci Declared Inoperable During Startup Testing | While performing the HPCI Pump Operability Test (34SV-E41-005-2), HPCI failed to start. Upon starting the HPCI Turbine, the turbine control valve failed to open. It was observed that alarm 'Oil Filler Differential Pressure High' was received (setpoint 11 psid). Local indication indicated that the differential pressure was 12 psid. Operators locally at the turbine did not observe any movement of the turbine shaft. The HPCI system was returned to standby and an investigation by Engineering and I & C has been initiated. (The licensee) suspects a problem with the EGR (Electronic Governor Module). The licensee will remain at the current power level and mode until the HPCI is repaired. The licensee notified the NRC Resident Inspector. | ||
| ENS 43221 | 8 March 2007 01:50:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpci Declared Inoperable Following Surveillance Testing | While Performing HPCI ATTS Panel, 1H11-P927, Functional Test & Calibration Surveillance (57SV-SUV-013-1S) For Ambient Torus Temperature High, The HPCI System Isolated. The Functional Test & Calibration Was Complete. The Isolation Was Reset. Following Return Of The Test Switch To Normal, HPCI Isolation Trip Logic 'A' Initiated & Closed 1E41-F002. HPCI Isolation Valve F002/F003 Alarm Annunciated When The Isolation Valve Started Closing & The HPCI Turbine Trip Solenoid Energized. I&C Investigating Time Delay Relay For Possible Cause. HPCI has been declared inoperable placing Unit 1 in TS LCO A/S 3.5.1.c - 14 days to restore. The licensee informed the NRC Resident Inspector. | ||
| ENS 43153 | 8 February 2007 09:32:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection (Hpci) System Inoperable | During performance HPCI Pump Operability (34SV-E41-002-1), HPCI Steam Supply Valve (1E41-F001) failed to open. When steam supply valve control switch was taken to open position, double indication was observed; however, HPCI turbine speed did not increase. Shortly afterward, HPCI Valve overload alarm was received. When steam supply control switch was taken to close position, a ground indication was received. The steam supply valve breaker tripped and ground indication cleared. Personnel in the field reported that the steam supply valve motor was hot to the touch. All other required safety systems are operable and available. The electrical power system is in a normal configuration with no power sources unavailable. The licensee will notify the NRC Resident Inspector. | High Pressure Coolant Injection | |
| ENS 43152 | 7 February 2007 21:40:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolent Injection (Hpci) Declared Inoperable | The HPCI minimum flow valve was found to have no position indication. The valve was verified to be in the closed position. Maintenance subsequent investigation found the control power fuse to be blown in the breaker, rendering it inoperable to stroke on low flow as designed. HPCI then declared inoperable." The fuse has been replaced and they position indication for HPCI minimum flow valve. Licensee entered Technical Specification 3.5.1 (14 day limiting condition of operation). All other Emergency Core Cooling Systems and the Emergency Diesel Generators are fully operable. The NRC Resident Inspector was notified of this event by the licensee. | Emergency Diesel Generator Emergency Core Cooling System | |
| ENS 42914 | 17 October 2006 15:21:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Accident Mitigation - Hpci System Inoperable | Unit HPCI system declared inoperable. During performance of the quarterly surveillance, HPCI pump operability, the HPCI system was secured when the "HPCI Turbine Oil Pressure Low" alarm was received and confirmed. Turbine governor end bearing oil pressure was 2 PSIG. The alarm setpoint is 6 PSIG and procedure limit is 10-12 PSIG. Pressure adjust valve was throttled open to raise pressure to 11 PSIG. The HPCI system was not immediately declared inoperable since an evaluation was being performed to determine if 2 PSIG turbine bearing oil pressure was adequate. Evaluation by the vendor will not be complete until 10/18/06. At 1655 hours, HPCI declared operable after a successful run with adequate oil pressure. HPCI is a single train system. The licensee notified the NRC Resident Inspector.
Original report was entered in error on 10/17/06 with Unit 2 versus Unit 1. Changed EN #42914 to accurately reflect the affected unit (Unit 1).
EN #42914 was submitted by Southern Nuclear Operating Company based upon a conservative decision to declare the HPCI system inoperable pending further evaluation to support its operability. Southern Nuclear Operating Company retracts EN #42914 based on the following discussion. During a subsequent review of the parameters by the HPCI Turbine Vendor, Dresser-Rand, and site engineering it was concluded that the HPCI system would have been capable of performing its intended safety function with the lower turbine governor end bearing oil pressure. During the operation of the system, the visual local indication was approximately 2.5 PSIG oil pressure at the governor end bearing. A review of the data showed that with a governor end oil pressure of the procedural minimal of 10 PSIG, the predicted oil flow rate would be 1.08 gpm with a minimum film thickness of 0.48 mils and a maximum bearing temperature of 228 deg F. With a degraded oil pressure of 2.5 PSIG, the predicted oil flow rate would be 0.54 gpm with a minimum film thickness of 0.46 mils and a maximum bearing temperature of 233 deg F. Based on the calculated data, the turbine governor end bearing would have performed satisfactorily for at least 8 hours at an oil pressure of 2.5 PSIG. Using the design basis success criteria, HPCI operation is successful if the system can inject water through the core Feedwater line for a total of 4 hours over a 24 hour period. The 4 hour mission time for HPCI is based on the design basis - if HPCI fails, it is backed up by the Automatic Depressurization System (ADS) in combination with Core Spray and Low Pressure Coolant Injection. The HPCI system is not credited for long term injection or late injection. Although the oil flow rate was reduced by 50% and the minimum film thickness reduced by 4%, the bearing temperatures were predicted to only increase a maximum of 5 deg F. Supporting this conclusion is the fact that the bearing was not damaged during the operation with low oil pressure when the turbine was run for 9 minutes at 2.5 PSIG governor end bearing oil pressure. The licensee will notify the NRC Resident Inspector. | Feedwater Core Spray Automatic Depressurization System Low Pressure Coolant Injection | |
| ENS 42657 | 21 June 2006 04:15:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection (Hpci) Declared Inoperable Due Excessvie Aux Oil Pump Motor Current | During routine weekly operation of High Pressure Coolant Injection (HPCI) Auxiliary Oil Pump (AOP), 2E41C002-3, the pump displayed indications of excessive motor current after the pump had been inservice for approximately 45 minutes. The pump was secured and, following review of electrical diagrams and consultation with Electrical Maintenance, the operating current of the AOP was checked and determined to be excessive. The AOP was declared inoperable, with the AOP inoperable, the HPCI system cannot be considered operable. The HPCI System is a single train ECCS system. Investigation into the cause of the high motor current is ongoing. All other Emergency Core Cooling Systems are fully operable including Reactor Core Isolation Cooling (RCIC). The NRC Resident Inspector was notified of this event by the licensee.
Retraction of NRC Event # 42657: After further review and evaluation it has been determined that the eight hour call made June 21, 2006 per the guidance of 50.72(b)(3)(v)(D) should be retracted. On 06/21/2006 at approximately 0015 EDT, Unit 2 was at 100 percent Rated Thermal Power. During routine weekly operation of the High Pressure Coolant Injection (HPCI) Auxiliary Oil Pump, 2E41-C002-3, the pump displayed indications of excessive motor current after the pump had been in-service for approximately 45 minutes. Investigation revealed the running amps to be 46 amps with nameplate data running amps shown as 27 amps. An evaluation was performed for the as-found condition that considered the cause and effects of the increased running amps on the ability of the auxiliary oil pump to perform its design function. Specifically, the effect of a shunt resistor short to open was reviewed. Areas reviewed for impact were motor speed, system over pressurization, motor insulation, Environmental Qualification, and motor service life. The results of the evaluation showed that significant margin existed to ensure the auxiliary oil pump design function was maintained. Therefore, the auxiliary oil pump operability was maintained and HPCI operability was also maintained. The HPCI system was immediately removed from service using normal plant procedures; a work order initiated, and the existing motor was replaced to ensure continued long term reliability. The licensee notified the NRC Resident Inspector. Notified R2DO (Ernstes) | High Pressure Coolant Injection Reactor Core Isolation Cooling Emergency Core Cooling System | |
| ENS 42578 | 16 May 2006 13:38:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpci Inoperable Due to Hpci Discharge Check Valve Body Leak | The Unit 2 High Pressure Coolant Injection (HPCI) system was declared inoperable due to a leak occurring in the pump discharge check valve (2E41-F005). Specifically, the HPCI system was started as part of a planned surveillance. Personnel observing the HPCI surveillance locally saw water discharging from underneath the insulation on the check valve. The individual, being in constant communication with the Main Control Room personnel, immediately notified the Reactor Operator of the leak. The operator subsequently secured HPCI and isolated the leak. The leak was later estimated to be approximately 20 gpm. The water is supplied from the Condensate Storage Tank. All water was contained in the HPCI room and processed by the room sump system. Investigations are continuing into the nature and cause of the leak. The licensee informed the NRC Resident Inspector. | High Pressure Coolant Injection | |
| ENS 42262 | 16 January 2006 23:31:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Hpci System Isolated Due to Atts Card Failure | HPCI (High Pressure Coolant Injection) isolation rendered the HPCI system inoperable. An ATTS card 2E41-N658B, for HPCI steam line low pressure, failed. Concurrent with this card failure was several annunciators, one of which was 'HPCI Steam Line Diff. Press High'. One HPCI steam line low pressure card failing or tripping will not cause a HPCI isolation, but one HPCI steam line differential press high trip condition (indication of high flow) will cause an isolation. Both of these cards are fed from the same power supply. Investigation to confirm the isolation cause is in progress. Licensee indicated 2E41-F003, outboard isolation valve, auto closed and 2E41-F002, inboard isolation valve was manually closed. The licensee notified the NRC Resident Inspector. | High Pressure Coolant Injection | |
| ENS 40824 | 17 June 2004 09:21:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Pressure Coolant Injection (Hpci) Declared Inoperable | While changing out a light bulb in the Unit 1 HPCI room, the surveillance operator noticed that the bolts for the HPCI pump discharge check valve, 1E41-F005, bonnet on pressure seal were loose. All six bolts could be turned by hand. HPCI was declared inoperable until an investigation is performed. The bolts were properly torqued and HPCI pump run is complete and sat. Licensee entered Technical Specification 3.5.1 (14 day Limiting Condition of Operation). All other Emergency Core Cooling Systems are fully operable including the Reactor Core Isolation Cooling System. The NRC Resident Inspector was notified of this event by the licensee.
The following information was obtained from the licensee via facsimile: A subsequent investigation revealed that a hot torque of the Unit 1 HPCI pump discharge check valve (1E41-F005) was performed during the 165 psig pump operability surveillance test which was performed following reassembly during the Unit 1 refueling outage. During this surveillance, the pump discharge pressure and thus internal pressure on the pressure seal cover, is maintained between 265 and 305 psig. However, during the rated pressure run, the pump discharge pressure achieved is required to be greater than or equal to 1135 psig. This difference in internal pressure (1135-305 = 830 psig minimum), acting on the bottom of the pressure seal cover, forced the pressure seal cover to move upward toward the cover retainer, compressing the pressure seal more tightly. As the pressure seal cover moved toward the cover retainer, the retainer bolts also moved upward, but the cover retainer remained stationary, due to gravity. Therefore, the retainer bolts were no longer torqued against the retainer cover, creating the 'as found' condition. It is site and vendor (Flowserve) experience that once the pressure seal cover is wedged upward, sufficient friction exists between the pressure seal cover, the pressure seal, and the valve body to prevent the pressure seal cover from relaxing the sealing force on the pressure seal once the valve internal (system) pressure is removed. Furthermore, no gap existed between the head of any of the retainer bolts and the retainer cover. The sealing function of the pressure seal was never lost, and the valve would have performed its design function while the retainer bolts were in the 'as found' 'finger tight' condition. Therefore, the valve remained operable at all times when the HPCI system was required to be operable following the Unit 1 refueling outage. This was further substantiated by the fact that no leakage was observed during the rated pressure pump operability run on 3/14/04. Following discovery of the 'finger tight' condition, the retainer bolts were cold torqued to the appropriate value (370 ft-lbs) by Maintenance personnel on 6/17/04. A HPCI pump surveillance was then performed and a hot torque of 370 ft-lbs was performed immediately after the system was shutdown. Tampering was considered as a possible cause for the loosened bolts, but no evidence could be found to support these bolts being loosened intentionally. All evidence available suggests that the bolts were loosened by internal pressure, which is consistent with vendor experience. Based on the above information this event is not reportable, and this notification serves to withdraw the previous notification made on 6/17/2004. The licensee has notified the NRC Resident Inspector. The Headquarters Operations Officer notified R2DO (Bonser). | High Pressure Coolant Injection Reactor Core Isolation Cooling Emergency Core Cooling System |