Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 45231 | 27 July 2009 16:51:00 | At about 10:00, on July 27, 2009, the Technical Support Center (TSC) HVAC was found to be degraded. The fan motor was running but there was no air flow and the TSC rooms were not being maintained with a positive pressure. Upon investigation, the fan housing was found partially filled with water, submerging the motor and preventing air flow through the system. Repair of the motor will take more than one day and is being immediately pursued. This affects the ability of the TSC ventilation to maintain adequate radiological habitability in the event of an emergency with an airborne radiological release. All other capabilities of the TSC are unaffected by this emergent repair. Existing procedures provide direction to relocate TSC personnel in the event of a TSC habitability concern; however, the backup facility does not have standby electrical power or a filtered ventilation system. Therefore, this condition is considered a major loss of emergency assessment capability and is reportable under 10CFR50.72(b)(3)(xiii). The TSC HVAC was last functionally tested satisfactorily on 06/29/09. The licensee believes the water found in the HVAV fan housing may be a result of a clogged drain line. The licensee will inform the NRC Resident Inspector. |
| ENS 45324 | 3 September 2009 09:04:00 | This event is being reported via a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. In this case, the telephone report is not considered an LER. This report is being made under 10 CFR 50.73(a)(2)(iv)(A). During a maintenance activity to replace an Engineered Safeguards Actuation System (ESAS) relay, one of the two High Pressure Injection (HPI) valves (MU-V-16C) in the 'B' train partially opened. The HPI system consists of the 'A' and 'B' trains, with each train containing two HPI valves. The cause of the partial opening of the HPI valve was inadvertent contact with adjacent energized circuits during the replacement of the ESAS relay. This resulted in a momentary short circuit, which bypassed the normal actuation logic, causing the HPI valve to open approximately 0.17 inches before blowing the control power fuse that stopped the valve movement. The event resulted in the inadvertent transfer of approximately 1000 gallons of water from the Make-up Tank into the Reactor Coolant System (RCS), before the valve could be restored to the closed position. No other valves or components actuated as a result of the inadvertent short circuit. RCS volume and pressure were stabilized and returned to normal. The 'B' HPI train had been declared inoperable and the unit entered a 72 hour LCO at 1:03 AM on 7/10/2009 due to configuration requirements needed for the planned ESAS relay replacement. The inadvertent partial 'B' train HPI did not impact the 'A' HPI train, and the unit remained at full power during this event. Following troubleshooting and replacement of the control power fuse, MU-V-16C was tested and restored to OPERABLE at 4:59 AM on 7/11/2009. The licensee notified the NRC Resident Inspector. |
| ENS 44715 | 12 December 2008 08:25:00 | This event is being reported via a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. In this case, the telephone report is not considered an LER. This report is being made under 10CFR 50.73 (a)(2)(iv)(A). During Engineered Safeguards Actuation System (ESAS) logic testing on October 24, 2008, an invalid actuation of the following heat removal systems occurred: 'B' train of the Decay Heat River Water System (DR), 'B' train of the Decay Heat Closed Cooling Water System (DCCW), and the 'B' train of the Nuclear Services River Water System (NR). There was no injection into the Reactor Coolant System. The invalid actuation occurred when the channel under test was taken to its tripped position. Since ESAS utilizes a 2 out of 3 logic for actuation, another actuation signal was present on one of the two channels not being tested, satisfying the actuation logic for the affected systems. The invalid actuation of these heat removal systems during testing on October 24, 2008 was due to oxidation on a silver-plated contact in one of the other two channels that was not being tested. This contact oxidation caused a higher input resistance to the timer relay, which resulted in an inadvertent actuation of the relay and its associated systems. The contact oxidation was caused as a result of using silver plated contacts in a low voltage application (approximately 12 VDC). During this invalid actuation, the heat removal systems were fully actuated. These heat removal systems functioned successfully and the operation of these systems did not have any adverse impact on plant operation. All of the silver-plated contacts in the affected circuits will be replaced with gold-plated contacts. The contacts are scheduled to be replaced by December 18, 2008. The NRC Resident Inspector has been notified. |
| ENS 44295 | 13 June 2008 12:05:00 | The following Part 21 notification was received via fax: On June 13, 2008, AmerGen Energy Company, LLC (AmerGen) completed a reportability determination which concluded that relay contacts contained an underlying design vulnerability that created a failure mode, and were reportable under Part 21, since the underlying vulnerability could create a substantial safety hazard. The relay contacts are Commercial Grade items dedicated by AmerGen. The relay contacts are provided by Joslyn Clark Controls Inc. (formerly AO Smith) as Normally Closed (N/C) open top contact assemblies (part numbers KPM-44, KPM-46, KPM-6A, and KPM-4A). These contacts are used in safety related applications, primarily in the engineered safeguards actuation system (ESAS). They are also used in safety related applications in the makeup/high pressure injection (HPI) system, main steam system, and the heat sink protection system (HSPS). The underlying vulnerability associated with the N/C Joslyn Clark contact is the design of the nylon contact arm. The design allows the contact to become configured incorrectly during assembly or following maintenance. If installed improperly, the moving contactor can hang up on the lip of the slot in the nylon actuator. The hang up results in failure of the contact to fully close and perform its function. Following proper assembly, the N/C Joslyn Clark contacts will not become hung-up during normal relay operation. As a result of this exposed design vulnerability, the Commercial Grade Dedication (CGD) plans as well as the maintenance procedures have been enhanced to prevent a relay from being placed into service with an improperly configured contact. Extent of condition reviews performed to date on relays installed in the plant, have not identified any of these deficiencies. The NRC resident inspector was notified of this part 21 notification by the licensee. |
| ENS 43498 | 17 July 2007 15:17:00 | This event is being reported via a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. In this case, the telephone report is not considered an LER. This report is being made under 10CFR 50.73 (a)(2)(iv)(A). During Engineered Safeguards Actuation System (ESAS) logic testing on June 27, 2007, an invalid actuation of the 'A' train of the Decay Heat River Water System (DR) occurred. The DR is comprised of the 'A' and 'B' trains, and serves as the reactor's ultimate heat sink. The ESAS has three independent input channels, which cause actuation in a two out of three logic. During ESAS logic testing, the channel under test is placed in the tripped state. Actuation relays in the other two channels should remain energized by the outputs from the other two channels not under test. The invalid actuation of the 'A' DR train during testing on June 27, 2007, was due to a failed ESAS relay in one of the other two channels not being tested. During this invalid actuation, the 'A' DR train was fully actuated. The operation of this normally standby system did not have any adverse impact on plant operation, nor any negative impact on the DR. The failed relay that caused the invalid actuation during ESAS logic testing did not impact the OPERABILITY of the ESAS, since the relay was failed in the actuated state. The failed relay was replaced on June 29, 2007. The licensee notified the NRC Resident Inspector. |
| ENS 41663 | 3 May 2005 14:32:00 | TMI Issue Report # 329440 identifies an issue associated with a previously unidentified/unanalyzed Appendix R fire scenario involving multiple high impedance faults. An engineering evaluation has determined that certain safety related power circuits are not protected against multiple high impedance faults, which in combination with a fire in the 305' elevation of the Control Building, could cause a loss of safe shutdown functions from the control room and the remote shutdown panel. An hourly fire-watch has been established in the affected fire zone in the 305' elevation of the Control Building as an interim compensatory measure. The NRC Resident Inspector will be notified. |
| ENS 40296 | 4 November 2003 15:50:00 | On November 4, 2003, during the TMI Unit 1 15th (T1R15) refueling outage, an inspection of the Pressurizer Heater Bundle (PHB) Diaphragm Plate was completed. This Inspection identified a leak path emanating from the lower Pressurizer Heater Bundle. The initial indication of a potential Reactor Coolant System (RCS) leak was boric acid residue located between the PHB Diaphragm Plate and the PHB Cover Plate. Initially the leak was believed to be from a seal weld, which is considered comparable to a gasket leak. Following disassembly of the PHB Cover Plate and performance of NDE, it was determined that the pathway was through the edge of the PHB Diaphragm Plate. This degraded condition of the PHB Diaphragm Plate is indicative of a RCS pressure boundary leak. This notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(A)." The licensee provided the following pre-refuel outage information: RCS Leak Rate = less than 0.1 gallons per minute Activity = 0.45 microcuries/milliliter TS (Technical Specifications) Limits: No leakage (3.1.6.4) Secondary System Activity = less than 1E-10 microcuries/milliliter The licensee has notified the NRC Resident Inspector. * * * UPDATE ON 11/24/03 AT 0114 EST FROM JOHN SCHORK TO HOWIE CROUCH * * * Subsequent to the initial report made on 11/4/03, the Pressurizer Heater Bundle (PHB) Diaphragm Plate was repaired. On November 23, 2003 during performance of post-maintenance testing inspections with the plant in Hot Shutdown, steam was observed emanating from either the seal weld or the PHB diaphragm plate. This update is being made to EN 40296 because the observed leak is being conservatively classified as a leak from the Primary System Pressure Boundary and is being addressed in a manner consistent with TMI Technical Specifications 3.1.6.4 and 3.1.6.6. An evaluation of the safety implications of the leak has been initiated. A condition report has been generated to capture all of the actions that have been and will be taken in response to the leak. The plant is being taken to cold shutdown in order to perform an inspection and repair of the leak. The plant continues to be subcritical with all control rods fully inserted and the Reactor Coolant System boron concentration is at the refueling boron concentration. The plant continues to remain in the T1R15 refueling outage. The NRC TMI-1 Sr. Resident Inspector has been notified of the leak. No other notifications were made to the State, Local or other governmental agencies. No press release has been issued regarding the event. The cause and corrective action to repair the leak will be addressed in the licensee event report being submitted in response to EN 40296. The location of the leak observed on November 23, 2003 is in the immediate vicinity of the lower Pressurizer Heater Bundle. There has been no determination of the volumetric leak rate. The leak consists (of) steam wisping from the location. The start date of the leak is November 23, 2003 and the leak was initially observed during hot shutdown checks at 1930 hours on November 23, 2003. There has been no radiological release to the environment as a result of this leak. The licensee has notified the NRC Senior Resident Inspector. Notified R1DO (John Rogge) and NRR (William Ruland). |