ENS 51448
ENS Event | |
|---|---|
13:32 Oct 4, 2015 | |
| Title | Unusual Event Declared Due to Identified Rcs Leakage > 25 Gpm |
| Event Description | At 0932 EDT on 10/4/15, the licensee declared an Unusual Event for identified RCS [Reactor Coolant System] leakage exceeding 25 gallons per minute [GPM], per EAL BU2, due to a relief valve leaking on the Shutdown Cooling System common header. The RCS leakage was within the capacity of the Charging System. At 0954 EDT the RCS leakage was terminated by isolating the Shutdown Cooling System. The cause of the relief valve failure is unknown and under investigation.
The RCS cooldown was terminated and both RCS loops were restored to service for decay heat removal using both Steam Generators and the Main Condenser. Current RCS temperature is 248 degrees F with RCS pressure at 248 psig. All offsite power and EDGs [Emergency Diesel Generators] are available. The licensee intends to repair the relief valve to resume the RCS cooldown using the shutdown cooling system.. The licensee informed State and local agencies and the NRC Resident Inspector. Notified DHS SWO, DHS NICC, FEMA, and Nuclear SSA via email.
The licensee terminated the Unusual Event at 1100 EDT, based on verification that the RCS leakage was stopped. The licensee informed State and local agencies and the NRC Resident Inspector. Notified R1DO (Bower), NRR EO (Morris), and IRD (Gott). Notified DHS SWO, DHS NICC, FEMA, and Nuclear SSA via email. |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.48 h-0.145 days <br />-0.0207 weeks <br />-0.00477 months <br />) | |
| Opened: | Fred Perkins 10:03 Oct 4, 2015 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Oct 4, 2015 |
| 51448 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Shutdown (0 %) |
| After | Hot Shutdown (0 %) |