ENS 42810
ENS Event | |
|---|---|
17:00 Aug 28, 2006 | |
| Title | High Pressure Coolant Injection Overspeed Trip Mechanism Failed to Reset |
| Event Description | 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. |
| Where | |
|---|---|
Vermont Yankee  Vermont (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+1.65 h0.0688 days <br />0.00982 weeks <br />0.00226 months <br />) | |
| Opened: | Michael Pletcher 18:39 Aug 28, 2006 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Sep 29, 2006 |
| 42810 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |