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| Entered date | Event description | |
|---|---|---|
| ENS 49109 | 12 June 2013 21:36:00 | 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 47238 | 3 September 2011 03:28:00 | 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 42810 | 28 August 2006 18:39:00 | 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 42120 | 4 November 2005 22:20:00 | PCIS Group 4 isolated during Reactor Protection Power Supply bus transfer. The isolation was not expected by control room operators prior to the power supply transfer. The isolation resulted in the trip of the running RHR pump. Operators verified proper isolation and reset the power supply. Shutdown cooling was re-established. The total time out of service was 18 minutes. The time to boil was calculated to be 68 hours prior to the event. The temperature at the RHR heat exchanger inlet at the beginning of the event was 90 degrees. The temperature at 22:20 was 92 degrees. The other RHR pump was available during this event. The plant is in refueling with the cavity flooded. The licensee notified the NRC Resident Inspector.
This notification updates the reporting criteria for Event No. 42120. The event was determined to not be reportable per 10CFR50.72 (b)(3)(iv)(A) since it was not due to a valid signal or the result of an intentional manual initiation. This report also satisfies the 60 day telephone notification provisions in 10CFR50.73 (a)(1). This notification is being made in accordance with 10CFR50.73 (a)(2)(iv)(A) due to an invalid Primary Containment Isolation System (PCIS) Group 4 actuation that impacted the availability of the Residual Heat Removal (RHR) shutdown cooling system. On November 4, 2005, with the reactor shutdown for refueling, an invalid actuation of PCIS Group 4 occurred during transfer of 'A' RPS Bus power supply. The actuation occurred because a breaker supplying power to the 'B' logic was tagged open resulting in completing the PCIS actuation logic. The Group 4 actuation resulted in a complete isolation of the single train RHR shutdown cooling suction path by isolation of RHR-17 and RHR -18 isolation valves. The shutdown cooling path was isolated for approximately 18 minutes and the time to boil was approximately 68 hours at the time of the event. The licensee informed the NRC Resident Inspector. Notified R1DO (Barkley). |