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| Entered date | Site | Region | Reactor type | Event description | |
|---|---|---|---|---|---|
| ENS 52787 | 3 June 2017 09:29:00 | Vermont Yankee | NRC Region 1 | GE-4 | A contract employee had just arrived on-site and sat down at his desk within the protected area. He was taken to the Brattleboro Memorial Hospital where he passed away later in the morning. A news release is planned. |
| ENS 51831 | 30 March 2016 11:58:00 | Vermont Yankee | NRC Region 1 | GE-4 | A non-licensed, licensee supervisory employee had a confirmed positive test for alcohol during a random fitness-for-duty test. The employee's access to the plant has been removed. The licensee notified the NRC Region I. |
| ENS 50164 | 3 June 2014 06:42:00 | Vermont Yankee | NRC Region 1 | GE-4 | This notification is being made in accordance with 10 CFR 50.73 (a)(2)(iv)(A) to provide information pertaining to an invalid Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment valves in more than one system. On April 5, 2014, with the reactor at 100% power, an invalid PCIS Group 3 actuation occurred from a momentary spike of the 'A' Refuel Floor radiation monitor which reached the instrument's high radiation trip set point. A radiation protection technician was dispatched to the refuel floor and dose rates in the vicinity of the 'A' radiation monitor detector were verified to be normal and below the alarm set points. The radiation monitor was verified to be indicating normal expected radiation levels. The detector was replaced, a functional check and calibration of the radiation monitor was completed satisfactory and the instrument channel was returned to service. The issue has been entered into the station's corrective action program. Both trains of Standby Gas Treatment System started as designed and Reactor Building ventilation isolated as a result of the invalid PCIS actuation. The PCIS functioned successfully, providing a complete Group 3 isolation. PCIS Group 3 involves the following system isolation valves: Drywell and Suppression Chamber Air and Vent: V16-19-6, 6A, 6B, 7, 7A, 7B, 8, 9, 10, 23 Containment Makeup: V-16-20-20, 22A, 22B Containment Air Sampling: VG-23, 26, V109-76A, 76B Containment Air Compressor Suction: V72-38A, 38B Containment Air Dilution: VG-9A, 9B, 22A, 22B, NG-11A, 11B, 12A, 12B, 13A, 13B Since no actual high radiation condition existed which required the PCIS Group 3 isolation, and the actuation was not in response to actual plant conditions satisfying the requirements for isolation, this event has been classified as an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. In accordance with 10 CFR 50.73(a)(1) a telephone notification is being made instead of submitting a written Licensee Event Report. The licensee has notified the NRC resident inspector. |
| ENS 49934 | 20 March 2014 08:50:00 | Vermont Yankee | NRC Region 1 | GE-4 | A non-licensed contract employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The licensee notified the NRC Resident Inspector. |
| ENS 49825 | 13 February 2014 10:16:00 | Vermont Yankee | NRC Region 1 | GE-4 | This notification is being made in accordance with 10 CFR 50.73 (a)(2)(iv)(A) to provide information pertaining to an invalid Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment valves in more than one system. On 12/15/2013, with the reactor at 100% power, invalid PCIS Group 3 actuation occurred from a momentary spike of the 'B' Refuel Floor radiation monitor which reached the instrument's high radiation trip set point. A radiation protection technician was dispatched to the refuel floor and dose rates in the vicinity of the 'B' radiation monitor detector were verified to be normal and below the alarm set points. The radiation monitor was verified to be indicating normal expected radiation levels. The detector and trip unit were replaced, a functional check and calibration of the radiation monitor was completed satisfactory and the instrument channel was returned to service. The issue has been entered into the station's corrective action program. Both trains of Standby Gas Treatment System started as designed and Reactor Building ventilation isolated as a result of the invalid PCIS actuation. The PCIS functioned successfully providing a complete Group 3 isolation. The PCIS Group 3 isolation involves the following systems: Drywell and Suppression Chamber Air and Vent: V16-19-6, 6A, 6B, 7, 7A, 7B, 8, 9, 10, 23 Containment Makeup: V-16-20-20, 22A, 22B Containment Air Sampling: VG-23, 26, V109-76A, 76B Containment Air Compressor Suction: V72-38A, 38B Containment Air Dilution: VG-9A, 9B, 22A, 22B, NG-11A, 11B, 12A, 12B, 13A, 13B Since no actual high radiation condition existed which required the PCIS Group 3 isolation, and the actuation was not in response to actual plant conditions satisfying the requirements for isolation, this event has been classified as an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. In accordance with 10 CFR 50.73(a)(1) a telephone notification is being made instead of submitting a written Licensee Event Report. The licensee has notified the NRC Resident Inspector. |
| ENS 49514 | 7 November 2013 15:52:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 11/7/13, it was identified that a missing conduit flood seal between an outside manhole and the West switchgear room compromised the flooding design of both the East and West switchgear rooms. Compensatory measures were implemented for the flood seal in accordance with the plant's barrier control process. Repair of the seal is in progress. The event is being reported under 10CFR 50.72(b)(3)(v) as internal flooding of both Switchgear Rooms could affect (a.) safe shutdown, (b.) removal of decay heat, (c.) control of release of radioactive material and (d.) mitigating an accident. The NRC Senior Resident Inspector has been notified of this condition. |
| ENS 49358 | 19 September 2013 13:17:00 | Vermont Yankee | NRC Region 1 | GE-4 | This notification is being made in accordance with 10CFR50.73 (a)(2)(iv)(A) to provide information pertaining to an invalid Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment valves in more than one system. On 7/23/2013, and again on 7/24/2013, with the reactor at 100% power, an invalid PCIS Group 3 actuation occurred from a momentary spike of the 'B' Reactor Building ventilation radiation monitor which reached the instrument's high radiation trip set point. A radiation protection technician was dispatched and radiation levels in the vicinity of the 'B' radiation monitor were verified to be normal and below the alarm set points. The radiation monitor was verified to be indicating normal expected radiation levels. Subsequent visual inspection and functional checks of the radiation monitors were completed satisfactory and the instrument channel was returned to service. At the recommendation from the vendor, the detectors were replaced in both of the Reactor Building ventilation monitors as well as the Refuel Floor radiation monitors. On 8/19/2013, 9/12/2013, and 9/13/2013, with the reactor at 100% power, invalid PCIS Group 3 actuations occurred from a momentary spike of the 'A' Refuel Floor radiation monitor which reached the instrument's high radiation trip set point. A radiation protection technician was dispatched to the refuel floor and dose rates in the vicinity of the 'A' radiation monitor detector were verified to be normal and below the alarm set points. The radiation monitor was verified to be indicating normal expected radiation levels. Subsequent visual inspection and functional checks of the radiation monitors were completed satisfactory and the instrument channel was returned to service. Both trains of Standby Gas Treatment System started as designed and Reactor Building ventilation isolated as a result of the invalid PCIS actuation. The PCIS functioned successfully providing a complete Group 3 isolation. The PCIS Group 3 isolation involves the following systems: Drywell and Suppression Chamber air and vent: V16-19-6A, 6B, 7, 7A, 7B, 8, 9, 10, 23 Containment Makeup: V-16-20-20, 22A, 22B Containment Air Sampling: VG-23, 26, V109-76A, 76B Containment Air compressor suction: V72-38A, 38B Containment Air Dilution: VG-9A, 9B, 22A, 22B, NG-11A, 11B, 12A, 12B, 13A, 13B Since no actual high radiation condition existed which required the PCIS Group 3 isolation, and the actuation was not in response to actual plant conditions satisfying the requirements for isolation, this event has been classified as an invalid actuation. This event did not result in any adverse impact to the health and safety of the public. In accordance with 10CFR50.73(a)(1) a telephone notification is being made instead of submitting a written Licensee Event Report. The licensee has notified the NRC resident inspector. |
| ENS 49355 | 18 September 2013 18:48:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 9/18/13, during performance of the High Pressure Coolant Injection (HPCI) pump operability surveillance, a minor steam leak was discovered on the governor valve inspection cover flange. Due to the leak, HPCI was declared inoperable. Actions taken: A 14-day LCO per TS 3.5.E.2 has been entered and corrective actions are in progress. The licensee has notified the NRC Resident Inspector.
After further evaluation, the gasket leak at the flange was determined to have no impact on the operability of the HPCI system, and therefore the HPCI system was able to perform all safety functions with the identified condition. The immediate determination, made on September 18, 2013, that the HPCI system was inoperable was revised based on the results of an analysis of the HPCI room heat up rate. The heat up rate was modeled using a calculated steam leak rate based on actual measurements of the damaged gasket after removal from the HPCI turbine flange. The time to heat up was based on the first set point at which isolation due to a temperature increase would occur. It was determined that the existing gap in the gasket represented approximately one-tenth of the approximate size of a steam leak that would be expected to result in an isolation, therefore the existing flange leak had no impact on operability of the HPCI system or its ability to mitigate the consequences of an accident. The licensee has notified the NRC site Resident Inspector. Notified R1DO (Krohn). |
| ENS 49211 | 24 July 2013 07:55:00 | Vermont Yankee | NRC Region 1 | GE-4 | This notification is being made in accordance with 10CFR50.73(a)(2)(iv)(A) to provide information pertaining to an invalid Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment valves in more than one system. On 6/14/2013, and again on 7/11/2013, with the reactor at 100% power, an invalid PCIS Group 3 actuation occurred from a momentary spike of the 'A' Refuel Floor radiation monitor which reached the instrument's high radiation trip setpoint. A radiation protection technician was dispatched to the refuel floor and dose rates in the vicinity of the 'A' radiation monitor detector were verified to be normal and below the alarm setpoints. The radiation monitor was verified to be indicating normal expected radiation levels. Subsequent visual inspection and functional checks of the radiation monitors were completed satisfactory and the instrument channel was returned to service. The cause of the spurious spikes is attributed to an unknown source of electrical noise. The issue with spurious spiking has been entered into the station's corrective action program. Both trains of Standby Gas Treatment System started as designed and Reactor Building ventilation isolated. The train actuation was complete. The PCIS functioned successfully providing a complete Group 3 isolation. The PCIS Group 3 isolation involves the following systems. Drywell and Suppression Chamber air and vent: V16-19-6A, 6B, 7, 7A, 7B, 8, 9, 10, 23 Containment Makeup: V-16-20-20, 22A, 22B Containment Air Sampling: VG-23, 26, V109-76A, 76B Containment Air compressor suction: V72-38A, 38B Containment Air Dilution: VG-9A, 9B, 22A, 22B, NG-11A, 11B, 12A, 12B, 13A, 13B In accordance with 10CFR50.73(a)(1) a telephone notification is being made instead of submitting a written Licensee Event Report. The licensee has notified the NRC Resident Inspector and will notify the State and local agencies. |
| ENS 49109 | 12 June 2013 21:36:00 | Vermont Yankee | NRC Region 1 | GE-4 | Vermont Yankee Control Room was notified by E-Plan personnel at 1638 (EDT) that the tone test initiated by the National Weather Service from Albany, NY, failed to activate tone alert radios via the Ames Hill NOAA transmitter and would be out for greater than one hour. At 1712 (EDT) the tone alert radios were functionally tested from the backup transmitter link (WTSA Radio Studio) satisfactorily verifying the ability to activate tone alert radios is available. The licensee suspects a phone service change was not sufficiently tested. The licensee notified the NRC Resident Inspector.
On 6/13/13 at 1045 EDT, the Ames Hill transmitter was returned to service after restoration of the transmission link between Ames Hill and the National Weather Service. The licensee notified the NRC Resident Inspector. Notified R1DO (Dentel). |
| ENS 48847 | 24 March 2013 13:16:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 3/23/13 it was identified that a conduit flood seal between an outside manhole and the switchgear rooms is displaced. This degraded flood seal compromises the flooding design of both the East and West Switchgear Rooms. Compensatory measures were implemented for the flood seal in accordance with the plants barrier control process. Repairs of the seal are in progress. Per the licensee these switchgear rooms contain both normal and safety related 4kV and 480 V electrical boards. Compensatory measures implemented include: Plant Maintenance personnel will take actions to seal any leak within 24 hours of a flooding event and also provide sump pumps to remove any water that has leaked in. The licensee notified the NRC Resident Inspector and the Vermont State Liaison.
This is an update to NRC Event No. 48847 reported on 3/24/13 at 1316 (EDT). On 3/27/2013 the extent of condition review identified two additional possible water intrusion paths from the outside to the switchgear rooms. Compensatory measures were implemented for these paths in accordance with plant procedures. Efforts to seal these paths are in progress. This is an on-going extent of condition assessment. The licensee will inform the NRC Resident Inspector and the Vermont State Liaison. Notified R1DO (Krohn). |
| ENS 48418 | 17 October 2012 16:05:00 | Vermont Yankee | NRC Region 1 | GE-4 | A non-licensed employee supervisor had a confirmed positive during a for-cause fitness for duty test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The NRC Resident Inspector has been notified. |
| ENS 47962 | 24 May 2012 21:59:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 5/24/12, it was identified that a conduit flood seal was missing between an outside manhole and the interior of the switchgear rooms. The missing flood seal compromised the interior flooding design for both East and West Switchgear Rooms. Repairs were made by procuring and installing a 4" flood seal so that the flood path has been plugged. The conduit plug seal is now functional. The event is being reported under 10CFR 50.72(b)(3)(v) as internal flooding of both Switchgear Rooms could possibly affect (a.)safe shutdown, (b.)removal of decay heat, (c.)control of release of radioactive material and (d.)mitigating an accident. The NRC Resident Inspector has been notified. |
| ENS 47542 | 21 December 2011 15:38:00 | Vermont Yankee | NRC Region 1 | GE-4 | On December 20, 2011, Vermont Yankee (VY) was notified by its vendor laboratory that a water sample, taken from the Connecticut River on November 3, 2011, tested positive for a low level of tritium (1120 pCi/L). This report is being made in accordance with 10 CFR50.72(b)(2)(xi) since VY is notifying government agencies and issuing a press release. The VY Off-Site Dose Calculation Manual contains effluent dose calculations that account for groundwater releases of this type. There is no impact on public health and safety as a result of this event. The licensee has notified the NRC Resident Inspector and the state of Vermont. |
| ENS 47500 | 6 December 2011 10:15:00 | Vermont Yankee | NRC Region 1 | GE-4 | This 60-day telephone notification is being made pursuant to 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1) to describe an invalid actuation of a containment heat removal system. On October 11, 2011, with the reactor shutdown for refueling, a partial loss of vital AC power was experienced which resulted in a loss of shutdown cooling as well as PCIS group 2, 3, 4, and 5 half isolations. The actuation was determined to be invalid as it occurred because a breaker supplying power to the 'A' vital AC was manually opened, resulting in actuation of the associated PCIS logic circuitry. The Group 4 actuation resulted in a complete isolation of the single train Residual Heat Removal shutdown cooling suction path. The shutdown cooling path was isolated for approximately 12 minutes resulting in a coolant temperature increase of approximately 2 degrees F. At the time of the event, the reactor cavity was flooded with the spent fuel pool gates removed and the normal fuel pool cooling system in operation to provide reactor cavity cooling. Based on this, there was no impact on public health and safety. The licensee notified the NRC Resident Inspector. |
| ENS 47495 | 2 December 2011 13:28:00 | Vermont Yankee | NRC Region 1 | GE-4 | While hanging tags on the 'B' Diesel Generator, which was tagged out for maintenance, the operator mistakenly entered the 'A' Diesel Generator Room and tripped the 'A' Diesel Generator fuel rack, making it inoperable. At this time both diesels were inoperable placing the plant in a 24 Hour LCO. When the fuel rack was tripped alarms were received in the control room, the operator was immediately contacted and the problem was identified and corrected. Total LCO time was approximately 2 minutes. The licensee notified the NRC Resident Inspector. |
| ENS 47379 | 27 October 2011 13:15:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 10/26/11 at approximately 11:25 a.m., while performing siren encoder maintenance and testing, the siren vendor inadvertently activated the EPZ sirens. New Hampshire, Massachusetts, Vermont and local emergency management directors were notified of the event. |
| ENS 47241 | 5 September 2011 09:40:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 9/5/11 at 0403 EDT, Vermont Yankee Nuclear Power Station experienced a lightning strike which resulted in a loss of all vertical temperature difference instrumentation. This condition is being reported as a loss of emergency assessment capability in accordance with 10CFR50.72(b)(3)(xiii) Procedure OPOP-PHEN-3127, Natural Phenomena, was entered and the lightning damage indicator walkdown checklist was performed with no additional damage found. Several other spurious alarms were received at the time of the lightning strike and are being investigated. None of these alarms indicate any other potentially reportable conditions. The plant is continuing normal power operation at approximately 98 percent rated thermal power. The NRC Resident Inspector has been informed. The licensee reports that repairs are currently underway. |
| ENS 47238 | 3 September 2011 03:28:00 | Vermont Yankee | NRC Region 1 | GE-4 | Technical specification required shutdown due to reactor recirculation unit #7 (RHR/CS Room Cooler) inoperable. This cooling unit impacts the operability of 'A' Low Pressure Coolant Injection (LPCI) and 'A' Core Spray (CS). Entered TS 3.5.A.6. Commenced reducing power for 24 hour cold shutdown LCO. The licensee has initiated repairs to the cooling unit. The licensee notified the NRC Resident Inspector.
The licensee exited TS 3.5.A.6 at 1000 EDT and declared CS operable after implementing compensatory measures. They are currently in a 7-day LCO Action Statement and expect to complete repairs within the time allowed. The Unit is currently holding power at 98%. The licensee informed the NRC Resident Inspector. |
| ENS 47200 | 26 August 2011 16:22:00 | Vermont Yankee | NRC Region 1 | GE-4 | At approximately 1345 EDT, on 8/26/2011, Entergy Corporation issued a press release regarding ongoing preparations at Vermont Yankee Nuclear Power Station for hurricane Irene currently located approximately 300 miles SSW of Cape Hatteras, NC. The purpose of the press release is to reassure the public regarding the safety and security of the facility and the extent of preparations that are in progress. Plant operation is not currently impacted, and the release of this information does not indicate a current threat to the facility or the health and safety of the public. The licensee has notified the NRC Resident Inspector. |
| ENS 46618 | 16 February 2011 15:29:00 | Vermont Yankee | NRC Region 1 | GE-4 | During system startup of (High Pressure Coolant Injection) HPCI for quarterly surveillance, audible and visual indications of steam leakage were observed. The system was secured and subsequently isolated (with outboard valve de-energized for configuration control). As a result of the steam leakage, a local fire alarm was received in the Control Room. HPCI is currently isolated and will not perform its safety function. Operators were dispatched to the Reactor Building fire panel to verify that the fire alarm was due solely to the steam leak. As a precautionary measure, personnel were evacuated from the Reactor Building. Operators entered (Off Normal Procedure) ON 3158, Reactor Building High Area Temperature/Water Level, and verified that room temperatures were decreasing after the steam line was isolated. No EOP-4, Secondary Containment Control, entry conditions were exceeded. The steam leak was isolated when HPCI was secured. Associated fire alarms were verified to be caused by the steam leak. There was no impact on other plant equipment or personnel safety. The source of the steam leak is suspected to be from a steam trap but this has not been confirmed. The licensee notified the NRC Resident Inspector and the State of Vermont Department of Public Service Nuclear Engineer. Notified R1DO (Ferdas) |
| ENS 46212 | 29 August 2010 19:58:00 | Vermont Yankee | NRC Region 1 | GE-4 | At 1905 EST, Vermont Yankee declared a Notice of an Unusual Event (NOUE) based on EAL SU 4.1, loss of 75% of the control room annunciators associated with safety related systems for greater than 15 minutes. Around 1845 EST, several annunciators were received and based on the failure mode, the licensee conservatively estimated that greater than 75% of the annunciators in the control room were inoperable. The licensee will notify the NRC Resident Inspector.
The licensee determined that the cause of the annunciator loss was a blown fuse. The fuse was replaced and the annunciators were restored without further issues. Vermont Yankee exited the NOUE at 2028 EST. The licensee has notified State authorities and will notify NRC Resident Inspector. Notified R1DO (Henderson), NRR EO (Evans), IRD (Gott), DHS (Vestal), and FEMA (Visce). |
| ENS 46070 | 6 July 2010 11:38:00 | Vermont Yankee | NRC Region 1 | GE-4 | Invalid Primary Containment And Vessel Isolation Control System (PCIS) signal results in partial actuation of Emergency Core Cooling System (ECCS) components: The following information is provided as a sixty (60) day telephone notification to the NRC in accordance with 50.73(a)(1) in lieu of the submittal of a written LER to report a condition that resulted in an invalid actuation of the high pressure coolant injection (HPCI) and reactor core isolation coolant (RCIC) systems. NUREG-1022, Revision 2, identifies the information that needs to be reported as discussed below. On May 17, 2010, during the Refueling Outage 28 ECCS test control room personnel identified the reactor vessel level was lowering. Valves HPCI-15 and 16 automatically isolated due to an invalid high steam flow isolation signal. The control room personnel immediately started both control rod drive (CRD) pumps as required by procedure. It was determined that the lowering of reactor vessel level was due to water flowing down the HPCI system and RCIC system turbine steam supply lines. The RCIC-15 valve was manually isolated terminating the event. At this time one CRD pump was secured. Acceptable water level in the reactor vessel was maintained throughout the event. The condition has been entered into the Vermont Yankee Nuclear Power Station Corrective Action Program for evaluation and implementation of corrective actions to preclude recurrence. The high steam flow isolation signal is considered invalid because: 1) At the time of the event, the unit mode switch was in a mode where PCIS was not required; 2) No steam was being generated; and 3) The water flow past differential pressure instrument generated a false high steam flow signal. The event is being reported in accordance with 50.73(a)(1) and 50.73(a)(2)(iv)(A) as an event or condition that as a result of an invalid initiation signal resulted in the actuation of one or more of the systems listed in paragraph 50.73 (a)(2)(iv)(B). The licensee has notified the NRC Resident Inspector. |
| ENS 46069 | 4 July 2010 21:30:00 | Vermont Yankee | NRC Region 1 | GE-4 | At about 1930 on 7/4/10 the control room was notified by the E-plan Duty Officer that the Ames Hill NOAA transmitter (Tone Alert Radio) was inoperable as of 1752 on 7/4/10. The E-plan Duty Officer has affected repairs and the transmitter is operable as of 2030. The licensee notified the NRC Resident Inspector. |
| ENS 46038 | 23 June 2010 15:16:00 | Vermont Yankee | NRC Region 1 | GE-4 | Event Description: An Unusual Event was declared at 1425 EDT due to reports from site personnel of an earthquake felt onsite. This was verified through the National Earthquake Information Center. Plant seismic monitors did not actuate. Actions Taken: Implemented OP 3127, Natural Phenomenon, for an earthquake. Plant personnel are walking down systems for any damage indications. (There is no indication of damage) at this time." The licensee informed state/local agencies and the NRC Resident Inspector. The licensee plans to issue a press release.
The Unusual Event was terminated at 1725 EDT. Plant walkdowns were completed with no damage noted. The licensee notified the NRC Resident Inspector. Notified the R1DO (Dwyer), NRR EO (Cunningham), DHS (Inzer), and FEMA (Hollis). |
| ENS 45987 | 8 June 2010 15:10:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 6/8/10 at 10:15, primary containment was declared inoperable and a 24 (hour) Limiting Condition for Operation (LCO) was entered due to Engineered Safety Features leakage in excess of the 1.0 gpm value assumed in the Alternative Source Term (AST) analysis as described in the UFSAR. The leakage was from the 'B' RHR heat exchanger relief valve (SR-10-86B) and was estimated at 1.25 gpm. On 6/8/10 at 11:26, commenced a power reduction for a Technical Specification required shutdown per TS 3.7.A.8. Actions Taken: Isolating the 'B' RHR system per Technical Specifications that will allow us to exit the 24 hour LCO. Planning to replace the relief valve. Verified relief valve on 'A' RHR system is not leaking. The licensee has notified State and local authorities and the NRC Resident Inspector. The licensee also anticipates a press release.
The licensee exited the 24 hour LCO TS required shutdown condition at 1548 EDT based on isolation of the 'B' RHR system. R1DO (Henderson) notified. |
| ENS 45958 | 27 May 2010 08:31:00 | Vermont Yankee | NRC Region 1 | GE-4 | At 0200 EDT on 5/27/10, operators identified that the FTS 2000, NAS (Nuclear Alert System) and commercial phones systems were not functional. ERDS is not functional. The loss of communications appears to be weather related. (The licensee) validated microwave communication with ISO New England and NRC is available. Cell phone communication is functional. The NRC and state were contacted using alternate means. The licensee has notified the NRC Resident Inspector.
Notified by the licensee that FTS 2000, NAS, commercial phone systems and ERDS are functional. The licensee will notify the NRC Resident Inspector. Notified the R1DO (Dwyer). |
| ENS 45957 | 26 May 2010 17:25:00 | Vermont Yankee | NRC Region 1 | GE-4 | At 1526 on 5/26/2010, while operators were increasing power with reactor recirculation flow, an RPS (Reactor Protection System) actuation occurred in both channels and all control rods inserted. RPV (Reactor Pressure Vessel) level decreased to 114.5 inches (Low level setpoint is less than 127 inches). Following the scram, the PCIS (Primary Containment Isolation System) groups 2, 3, 4 and 5 received actuation signals and all open valves isolated. Both trains of standby gas treatment system actuated. Plant actions taken included entering procedures OT-3100, Reactor Scram on RPS Actuation and EOP-1, RPV Control on Low Level Signal. The EOP-1 was exited per shift manager direction because of no emergency. The operators stabilized the plant and reset both RPS and PCIS. An investigation into the cause of the scram is continuing. Electrical power is being supplied from offsite sources through the startup transformers. The licensee notified the NRC Resident Inspector. |
| ENS 45613 | 7 January 2010 16:55:00 | Vermont Yankee | NRC Region 1 | GE-4 | On January 6, 2010, Vermont Yankee (VY) was notified that the results of fourth quarter 2009 ground water sampling, performed as part of the voluntary ground water monitoring program, identified a very low concentration of tritium in one well that is used to monitor station ground water. VY has notified state, local and other government agencies of this condition. Since no other wells indicated the presence of tritium and the concentration detected is below the reporting threshold identified in the Off-site Dose Calculation Manual, notifications were considered voluntary consistent with NEI 07-07 'Industry Ground Water Initiative - Final Guidance Document.' This report is being made in accordance with 10 CFR 50.72(b)(2)(xi) to notify the NRC of these voluntary notifications. There is no impact on public health and safety as a result of this event. The NRC Resident Inspector has been notified. |
| ENS 45313 | 31 August 2009 14:51:00 | Vermont Yankee | NRC Region 1 | GE-4 | A non-licensed employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's unescorted access to the plant has been revoked. Contact the Headquarters Operations Officer for additional details. The licensee has notified the NRC Resident Inspector. |
| ENS 45009 | 22 April 2009 13:37:00 | Vermont Yankee | NRC Region 1 | GE-4 | This sixty day notification is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A) to provide the NRC with information pertaining to an unplanned invalid actuation of specific systems, specifically, a Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment isolation valves in more than one system. On March 24, 2009, at approximately 1326 hours, Vermont Yankee Nuclear Power Station (VYNPS) experienced an invalid PCIS Group 3 isolation associated with personnel error during quarterly calibration of the Refuel Floor Zone Radiation Monitors. VYNPS had removed the East Refuel Floor Zone Radiation Monitor from service for calibration. The technician, in the field, had completed a phone communication with the control room and was dispatched to the East Refuel Floor Zone Radiation Monitor to perform the calibration activity. However, the technician incorrectly went to the inservice West Refuel Floor Zone Radiation Monitor and removed the detector from service. This incorrect action caused a momentary invalid high radiation signal containment isolation signal and the Subsequent PCIS Group 3 isolation. The following actuations resulted: Both trains of the Standby Gas Treatment System started as designed. The PCIS functioned properly providing a complete Group 3 isolation valves in the following system actuated as a result of the PCIS Group 3 isolation: Drywell Air Purge and Vent, Drywell and Suppression Chamber Main Exhaust, Suppression Chamber Purge and Vent, Containment Air Compressor Suction, Exhaust to Standby Gas Treatment, Containment Purge Supply and Makeup, Containment Air Sampling, Air Dilution Subsystem, (and) Containment Air Dilution Vent System. This event has been entered into VYNPS's corrective action program. The licensee has notified the NRC Resident Inspector. |
| ENS 44728 | 18 December 2008 11:23:00 | Vermont Yankee | NRC Region 1 | GE-4 | Loss of Ames Hill NOAA transmitter. Loss of the Ames Hill input from Albany, NY. Unable to establish backup input to Ames Hill transmitter from WTSA radio station, Brattleboro, VT. This results in a loss of output signal to area tone alert radios. Coordinating trouble shooting and repair with vendor. This action was successful in restoring service at 11:00, 12/18/08. The licensee notified the NRC Resident Inspector. |
| ENS 44539 | 3 October 2008 19:52:00 | Vermont Yankee | NRC Region 1 | GE-4 | Received Shipment from Pilgrim Station of temporary lead shielding that exceeds 10 CFR 20 requirements for a non-exclusive use limited quantity shipment of 0.5 mR on contact. Receipt inspection readings of the last container in the shipment measured between 1.3 mR and 1.85 mR (taken via 3 readings, using 3 separate meters and 2 different technicians). Per 10CFR20 subpart 1906 paragraph D, which states: (d) The licensee shall immediately notify the final delivery carrier and the NRC Operations Center (301-816-5100), by telephone, when -- (1) Removable radioactive surface contamination exceeds the limits of section 71.87(i) of this chapter; or (2) External radiation levels exceed the limits of section 71.47 of this chapter. The licensee notified the NRC Resident Inspector.
NRC Notification 44539 was conservatively made due to conservative procedural guidance. 10 CFR 20.1906(d)(2) requires immediate notification of the final delivery carrier and the NRC Operations Center when external radioactive levels exceed the limits of section 71.47 of this chapter. The reporting threshold contained in 10 CFR 71.47 is 200 mR (per hour) at any point on the external surface of the package. Since actual measured levels were between 1.3 mR (per hour) and 1.85 mR (per hour) this event is not reportable. ENS Event Number 44539, made on 10/03/08, is being retracted. The NRC Resident Inspector will be notified by the licensee of this retraction. Notified R1DO (Jackson) & NMSS EO (Regan). |
| ENS 44530 | 30 September 2008 20:44:00 | Vermont Yankee | NRC Region 1 | GE-4 | Loss of the Ames Hill NOAA transmitter (due to an) interrupted phone link between Albany and Ames Hill. Caused by a 'corruption' of the AT&T phone line between Albany and Ames Hill. This condition interrupted/interfered with the radio (frequency) link between WTSA radio station and the Ames Hill transmitter. Turn(ed) off corrupting phone lines interfering with radio frequency communications between Ames Hill transmitter and WTSA radio station. AT&T (was) contacted to repair phone line. The normal configuration is the phone line is used for the primary signal and the radio link to WTSA radio station is for backup capability. The licensee will be notifying the NRC Resident Inspector.
The licensee reported that offsite notification capability was restored at 2105 EDT by disconnecting the corrupted phone line which automatically switched the radio signal to WTSA radio station as the primary signal for activation. The radio station performed a silent test to verify functionality. The licensee will be notifying the NRC Resident Inspector of this update. Notified R1DO (White). |
| ENS 44118 | 3 April 2008 14:57:00 | Vermont Yankee | NRC Region 1 | GE-4 | When it was discovered that numerous plant personnel could not make telephone calls out of state, attempts were made to contact the states of Vermont, New Hampshire, and Massachusetts, as well as the NRC through the FTS phone. The NRC, as well as the state of Vermont were contacted but the NAS phone system was inoperable as well as the land lines to the states of NH and MA. Alternate means to contact the states were available via the microwave system. At 1430 all communications that were lost were restored. At 1445 all testing of communications were completed. The licensee notified the NRC Resident Inspector. |
| ENS 44042 | 7 March 2008 13:00:00 | Vermont Yankee | NRC Region 1 | GE-4 | On 3/7/08, at 1045, Vermont Yankee experienced a telephone service interruption that resulted in a loss of the dedicated phone line used to contact the NRC Operations Center via the Emergency Notification System (ENS) - FTS phone as well as a loss of the Nuclear Alert System (NAS) from the control room. Alternate phone communications remain available from the control room to both the NRC Operations Center as well as the states of Vermont, Massachusetts, and New Hampshire. The Emergency Planning organization has verified proper ENS - FTS and NAS communications from the Emergency Operations Facility (EOF). The licensee notified the NRC Resident Inspector. * * * UPDATE FROM KRITZER TO SNYDER ON 3/7/08 AT 1552 * * * Vermont Yankee's ENS and other phone lines are back in service. The licensee notified the NRC Resident Inspector. Notified R1DO (Caruso). |
| ENS 43729 | 18 October 2007 12:36:00 | Vermont Yankee | NRC Region 1 | GE-4 | This notification is being made in accordance with 10CFR50.73(a)(2)(iv)(A) to provide information pertaining to an invalid Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment isolation valves in more than one system. On 09/15/07, with the reactor at 100% power, an invalid PCIS Group 3 actuation occurred from a momentary spike of the 'A' Refuel Floor radiation monitor which reached the instrument's high radiation trip setpoint. Radiation protection technicians dispatched to the refuel floor verified dose rates in the vicinity of the 'A' radiation monitors detector to be normal and below the alarm set points. The radiation monitor was verified to be indicating normally to expected radiation levels. Subsequent visual inspection and functional checks of the radiation monitor were completed satisfactory and the instrument channel was returned to service. The cause of the spurious spike is attributed to an unknown source of electrical noise. Both trains of the Standby Gas Treatment System started as designed and Reactor Building ventilation isolated. The train actuation was complete. The PCIS functioned successfully providing a complete Group 3 isolation. The PCIS Group 3 isolation involves the following systems and isolation valves: Drywell and Suppression Chamber air purge and vent: V16-19-6, 6A, 6B, 7, 7A, 7B, 8, 9, 10, 23 Containment Makeup: V16-20-20, 22A, 22B Containment Air Sampling: VG-23, 26, V109-76A, 76B Containment Air compressor suction: V72-38A, 38B Containment Air Dilution: VG-9A, 9B, 22A, 22B, NG-11A, 11B, 12A, 12B, 13A, 13B In accordance with 10CFR50.73(a)(i) a telephone notification is being made instead of submitting a written Licensee Event Report. The licensee will notify the NRC Resident Inspector. |
| ENS 43610 | 30 August 2007 17:16:00 | Vermont Yankee | NRC Region 1 | GE-4 | Event Description: Reactor scram (4 hr notification) automatic scram Primary containment isolation of Groups 2,3,4, and 5 due to RPV Level < low level setpoint (<127") due to reactor scram. (8 hr notification). Actions Taken (reference applicable Technical Specifications): Implemented OT 3100 (Reactor Scram Procedure) EOP-1 (RPV Control). Placed the plant in a stable condition and implemented OP 0109, Plant Restoration. The NRC Resident Inspector was notified of this event by the licensee. Reactor was initially at approximately 63% power due to cooling tower damage which occurred more than a week ago. License was performing a surveillance test of the # 2 turbine stop valve. The valve was shut per the surveillance test procedure but they were unable to open the valve. Personnel were in the heater bay and mechanical assistance was applied to open the valve. The valve opened quickly at which point the licensee received a turbine stop valve closure signal which generated an automatic reactor scram. All rods fully inserted into the core. Reactor vessel water level decreased below 127 inches, due to the reactor scram, which caused primary containment isolation of groups 2,3,4 and 5. Reactor vessel water began to increase because Reactor feedwater pumps "A" & "B" were still operating. Reactor feedwater pump "B" was secured. When reactor vessel water increased to 173 inches, high level alarm, reactor feedwater pump "A" automatically tripped. Highest reactor vessel water level increased to was approximately 179 inches. No SRV's opened. All Emergency Core Cooling Systems, EDGs are fully operable if needed and the electrical grid is stable. Reactor vessel water level is being maintained using a reactor feedwater pump. Only other anomaly was that for some unknown reason automatic pressure control went to mechanical pressure control during the transient. Licensee is investigating the event. |
| ENS 43573 | 17 August 2007 10:35:00 | Vermont Yankee | NRC Region 1 | GE-4 | Received notification from VY E-Plan of an outage of the Ames Hill NOAA transmitter. Made notifications per AP 0156. E-Plan Duty Officer investigating the cause. Ames Hill NOAA transmitter restored at 1037. No sirens were affected during the transmitter outage. The licensee notified the NRC Resident Inspector. |
| ENS 43505 | 19 July 2007 10:28:00 | Vermont Yankee | NRC Region 1 | GE-4 | A licensed operator had a confirmed positive random fitness-for-duty test. The test sample was taken on 07/15/07 and the Medical Review Officer confirmed a positive test at 1515 EDT on 07/18/07. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector. |
| ENS 43413 | 8 June 2007 10:49:00 | Vermont Yankee | NRC Region 1 | GE-4 | During the performance of quarterly HPCI valve testing in accordance with OP4120 one of the two injection valves, HPCI-19, did not stroke open as required. Prior to testing the HPCI system was in normal standby line up. HPCI-19 was stroke tested during the outage on 6-1-07 and operated normally. HPCI-19 was also tested and verified to open during the ECCS test on 6-1-07. HPCI was declared inoperable per Technical Specification 3.5.E.2 (14 day Limiting Condition of Operation). All other ECCS systems and the EDGs are fully operable and the electrical grid is stable. The licensee has initiated repair efforts. The NRC Resident Inspector was notified of this event by the licensee. |
| ENS 43409 | 6 June 2007 14:32:00 | Vermont Yankee | NRC Region 1 | GE-4 | Notified at 1220 by Emergency Plan personnel that a tone test initiated by the National Weather Service from Albany, NY, failed to activate tone alert radios via the Ames Hill NOAA transmitter. Notified at 1317 that the WTSA Studio to transmitter link also failed to activate the tone alert radios. The tone alert radio system was working when a severe thunderstorm was issued at 1205 on 6-5-07. The licensee has sent a technician to repair the transmitter. The licensee notified the NRC Resident Inspector and will notify the states of Vermont, Massachusetts, and New Hampshire.
Repairs were completed to the tone alert radio system last night and testing was completed this morning. At 0821 the tone alert radio system was declared to be operable. The licensee notified the NRC Resident Inspector and the states of Vermont, Massachusetts, and New Hampshire. Notified R1DO (Barkley) |
| ENS 43113 | 22 January 2007 22:42:00 | Vermont Yankee | NRC Region 1 | GE-4 | The licensee discovered that the High Pressure Coolant Injection (HPCI) system flow control loop was degraded in such a manner that HPCI would not perform its safety function. The HPCI loop flow indicator indicated 200 GPM with no flow in the loop. The specification for that parameter is <100GPM. With the flow indicator in this condition the HPCI flow controller would perform non-conservatively (less flow into the system than was demanded), and would not perform its intended safety function therefore rendering HPCI inoperable. The licensee declared HPCI inoperable and in accordance with Technical Specification 3.5.E.2 entered a 14 day LCO. The licensee has commenced troubleshooting and will initiate repairs as necessary to return the system to operation. The licensee notified the NRC Resident Inspector.
BASIS FOR RETRACTION: NRC Event Notification 43113 was conservatively made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10CFR50.73 were met pending the evaluation of an atypical condition observed with the High Pressure Coolant Injection (HPCI) Flow Indicator that was observed by Operators during routine monitoring of plant equipment. After comparing the observed flow indication to allowable values for meter uncertainties, it was determined that the initial NRC Notification was not required. The HPCI system was capable of fulfilling all design safety functions. Additional measures to ensure system reliability were completed that included removing and bench testing the recently refurbished 'square root converter' and calibration verification of involved components. No degraded conditions were discovered. ENS Event Number 43113, made on 01/22/07, is being retracted. R1DO (Neil Perry) notified. The NRC Resident Inspector was notified of this retraction by the licensee. |
| ENS 42944 | 29 October 2006 13:38:00 | Vermont Yankee | NRC Region 1 | GE-4 | The facility lost the Ames Hill NOAA transmitter due to weather conditions. Compensatory measures are in place and the vendor has been notified and is enroute to shift the power supply to back up. The licensee notified the NRC Resident Inspector.
The Ames Hill NOAA transmitter was restored at 1505. The licensee will notify the NRC Resident Inspector. Notified R1DO (J. Noggle) |
| ENS 42872 | 3 October 2006 14:51:00 | Vermont Yankee | NRC Region 1 | GE-4 | Notification was to report that on 9/27/06 at 1418 hours a company employee self identified the use of a controlled substance. Access was immediately suspended; employee was mandatory referred to EAP and will require admission into the follow-up testing program. The employee is not involved in any safety related activities and is not licensed. The NRC Resident Inspector was notified of this event by the licensee. Contact the Headquarters Operations Officer for additional details. |
| ENS 42810 | 28 August 2006 18:39:00 | Vermont Yankee | NRC Region 1 | GE-4 | The High Pressure Coolant Injection system (HPCI) over-speed trip tappet did not reset as expected during the trip tappet test after securing from a successful HPCI operability run, thereby preventing a re-start of the HPCI system. The Automatic Depressurization System (ADS), Core Spray sub-systems, Low Pressure Coolant Injection (LPCI) and the Reactor Core Isolation Cooling (RCIC) systems are operable." The unit is in a 14 day LCO for this event. The licensee will notify the NRC Resident Inspector.
NRC Notification 42810 was conservatively made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10CFR50.72 were met pending the evaluation of condition observed with the High Pressure Coolant Injection (HPCI) Overspeed Trip reset feature that was discovered while performing scheduled testing for the HPCI System. During surveillance testing on 08/28/06, the HPCI System was started and satisfied the Technical Specification requirements designed to demonstrate HPCI System Operability. Subsequently, while testing the specific components of the system, the HPCI Overspeed Trip functioned as expected, but would not reset when manually depressed (locally). The Shift Manager declared the system inoperable and remained in the Limited Condition of Operation (LCO) that was entered prior to commencing the testing activities. Subsequent investigation determined that the reset function of the HPCI turbine overspeed trip device is not required to support HPCI from performing the system safety functions as described in the station design and licensing basis. ENS Event Number 42810, made on 08/28/06, is being retracted. The licensee notified the NRC Resident Inspector. The R1DO(Hott) has been notified. |
| ENS 42755 | 8 August 2006 17:40:00 | Vermont Yankee | NRC Region 1 | GE-4 | Licensee has experienced a loss of emergency response capability due to loss of the Ames Hill NOAA transmitter. This transmitter is used to transmit information to the radio alert system (weather alert) for the site. Contract vendor has been contacted for troubleshooting and repair and is enroute to investigate the problem. The site has the ability to use the local radio stations if necessary. The licensee has notified the NRC Resident Inspector. The licensee will be notifying the VT, NH, and MA State Police, the VT Department of Public Service, and the VT Emergency Management Office.
At 1840, Vermont Yankee was notified that the Ames Hill NOAA transmitter was operational. The cause of the failure was due to a possible lightning strike. The licensee notified the NRC Resident Inspector. The licensee will be notifying the VT, NH, and MA State Police, the VT Department of Public Service, and the VT Emergency Management Office. Notified R1DO (J Caruso). |
| ENS 42605 | 24 May 2006 21:52:00 | Vermont Yankee | NRC Region 1 | GE-4 | Licensee declared an Unusual Event due to a fire that was not extinguished within 10 minutes - EAL U4A. There were no flames, only smoke. Control Room received a Bus 2 ground alarm, reduced power, secured the B Main Feedwater Pump, inserted control rods below the Maximum Extended Load Limit Analysis (MELLA) line, and then secured the C Condensate Pump. The ground alarm cleared after securing the C Condensate Pump. CO2 discharged automatically into the switchgear room due to the smoke in the switchgear room. The switchgear room has been ventilated, site personnel have entered and no other damage to the switchgear has been identified other than the C Condensate pump breaker. Offsite Fire (Vernon Fire Department) responded to the site and is assisting with ventilation. One ambulance is responding to transport a Fire Brigade member that is not feeling well due to heat. The licensee has notified the NRC Resident Inspector, and State and Local emergency response organizations. Notified R1 PAO (Screnci).
Licensee called to terminate the Unusual Event. The plant is in a stable condition with no other outstanding problems. Ventilation of the switchgear room is continuing and air samples are being analyzed. The licensee has notified the NRC Resident Inspector, and State and Local emergency response organizations. Notified R1 (Holian, Powell, Bores), IRD (Blount), NRR EO (Haney), R1DO (Gray), DHS (Lee) and FEMA (Casto) |
| ENS 42235 | 28 December 2005 13:45:00 | Vermont Yankee | NRC Region 1 | GE-4 | This report is being made in accordance with 10CFR50.73(a)(2)(iv)(A) to provide the NRC with information pertaining to an invalid Primary Containment Isolation System (PCIS) Group 3 actuation signal that affected containment isolation valves in more than one system. On 11/02/05 with the reactor shutdown for a refueling outage, an invalid PCIS Group 3 actuation occurred while cycling a breaker during a tagging clearance activity. The invalid actuation occurred when the circuit was de-energized. This is an expected result of opening the breaker. The PCIS functioned successfully providing a complete Group 3 isolation. The train actuation was complete. Both trains of the Standby Gas Treatment System started as designed. The PCIS Group 3 isolation involves valves in the following systems: Drywell Air Purge and Vent Drywell and Suppression Chamber Main Exhaust Suppression Chamber Purge and Vent Containment Air Compressor Suction Valve Exhaust to Standby Gas Treatment Containment Purge Supply and Makeup Containment Air Sampling Air Dilution Subsystem Valves Vent Subsystem Valves Containment Air Dilution Vent System The licensee will notify the NRC Resident Inspector. |
| ENS 42219 | 22 December 2005 10:20:00 | Vermont Yankee | NRC Region 1 | GE-4 | The HPCI flow control current loop was found degraded in such a manner that HPCI would not perform its intended function. HPCI was declared inoperable per TS 3.5.E.2 (14 day LCO). Repair efforts have been initiated. The licensee notified the NRC Resident Inspector.
On 12/22/05, the HPCI System flow indicator 'spiked' a number of times with the system in its normal standby line-up. Control Room Operators declared the HPCI system inoperable and entered a 14 day LCO per TS 3.5.E.2, to troubleshoot and repair the system as appropriate. The safety function of HPCI system is to provide and maintain an adequate coolant inventory inside the reactor vessel to prevent fuel clad conditions from exceeding 10CFR50.46 criteria as a result of postulated small breaks in the Nuclear System process barrier. To ensure that this safety function is met, the HPCI System must be able to deliver a minimum actual flow rate of 3570 gallons per minute (gpm) to the reactor vessel. The actual flow rate was reduced below the Technical Specification value of 4250 gpm to account for potential flow instrument string inaccuracies. The delivery of 3570 gpm of actual flow demonstrates that sufficient margin to safety function is maintained during accident conditions. In automatic operation, the HPCI flow controller uses the flow signal to maintain a flow rate of 4250 gpm and is designed to automatically adjust developed flow rate in response to changes in flow signals. System operation is tested quarterly by monitoring flow to ensure that the HPCI system can perform its safety functions. The Technical Specification surveillance requirement states that the HPCI system shall deliver at least 4250 gpm at normal reactor operating pressure when recirculating to the Condensate Storage Tank. The event investigation revealed that the cause of the flow spikes was a malfunctioning electrical component in the power supply module within the flow controller. Power to the flow transmitter is supplied by this module. The power supply would malfunction for a few seconds and then would return to normal operation, thereby resulting in step changes in the HPCI flow signal. It is conservative to assume the actual HPCI flow rate would have been reduced by the full amount of the flow rate, for the entire duration of the flow signal. Additional conservatism also exists because the HPCI system flow is unlikely to have been able to respond to the full value of a short duration flow spike. When calculating the average HPCI flow rate, the impact of the flow spikes decreases as a longer period is evaluated because the duration of all of the flow spikes added together is very short and comparably longer periods of stable performance exist between the individual spikes. Therefore, it is conservative to evaluate the shortest period of time that HPCI is required to perform its safety functions that is stated in the Design Bases Document as 1000 seconds. With HPCI operable, the worst case period occurred just prior to it being declared 'Inoperable'. HPCI was calculated to have developed an actual flow rate of greater than 4191 gpm during the worst case 1,000 second period. The calculation for 'HPCI Flow Control & Indication Loop Accuracy' provides total loop accuracy of plus or minus 216.2 gpm at 4250 gpm for Design Bases Accident conditions. A calculated flow rate of 4191 gpm, minus the flow instrument loop uncertainty of 216 gpm yields a worst case actual flow rate of 3975 gpm. A flow rate of 3975 gpm is greater than the 3570 gpm assumed in event calculations. The subject flow controller power supply module was removed and bench tested to demonstrate that sufficient operating margin existed to provide reasonable assurance that the power supply would not have failed if called upon to mitigate a design bases accident with sufficient margin. The testing simulated HPCI operation at 4250 gpm for more than 24 hours. No flow spikes were recorded during this period. Based upon these test results and the analysis provided above, if the subject power supply component had remained in service and HPCI operation was required, the system would have performed its required safety function for a duration exceeding any analyzed event. ENS Event Number 42219, completed on 12/22/05, is being retracted. The licensee notified the NRC Resident Inspector. Notified R1 DO (J. Trapp) |