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| Entered date | Event description | |
|---|---|---|
| ENS 50797 | 9 February 2015 11:05:00 | The Unit 2 Stack High Range Radiation Monitor (RM-8168) was removed for service for planned maintenance. There is no significant effect of this planned maintenance on the plant. The licensee notified the NRC Resident Inspector, the State of Connecticut and Waterford township. |
| ENS 50836 | 20 February 2015 00:49:00 | A High Energy Line Break (HELB) boundary door was discovered not latching. HELB boundary affects both trains of safety related (480V) switchgear and was not operable for approximately seven minutes. (The licensee) entered the technical specification action statement, restored the door to functional, and exited the technical specification action statement. The licensee notified the NRC Resident Inspector, the State of Connecticut and local officials. |
| ENS 50676 | 12 December 2014 22:27:00 | The boundary door between the A and B safety related switchgear rooms was found not to be latching. This door is credited in the high energy line break (HELB) analysis. Both trains of safety related switchgear were affected for approximately 36 minutes. The technical specification action statement was entered, the door was repaired, and the action statement was exited. The licensee notified the NRC Resident Inspector. |
| ENS 50567 | 24 October 2014 20:59:00 | The normal range Supplemental Leakage Collection and Release System (SLCRS) was removed from service due to a sample pump failure. Compensatory sampling and monitoring is being established per the Radiological Effluent Monitoring and Offsite Dose Calculation Manual. Following the sample pump repairs and restoration, the Radiation Monitor will be returned to service. The licensee notified the NRC Resident Inspector, the State of Connecticut and Waterford township. |
| ENS 49467 | 23 October 2013 13:08:00 | Millstone Unit-2 is performing pre-planned maintenance on the power station stack and Unit-2 high range stack radiation monitors. The monitors are expected to be out of service for six hours. Notified the R1DO (Holody). |
| ENS 49260 | 9 August 2013 22:27:00 | The loss of a non-vital 480v bus resulted in a feedwater transient that caused steam generator water level to lower below the automatic reactor trip setpoint. The reactor trip and plant response was uncomplicated with all rods being inserted into the core. The auxiliary feedwater system automatically actuated and is currently being to used to feed the steam generators. Decay heat is being removed via the steam dumps to the condenser. No relief valves or safeties lifted during the transient. The plant is currently stable in Mode 3 at normal operating pressure and temperature and is in its normal shutdown electrical lineup. There was no impact on Unit 2 which is currently operating at 100% power. The licensee has notified state and local authorities and the NRC Resident Inspector. |
| ENS 48982 | 30 April 2013 05:06:00 | Systems affected: Main steam line radiation monitors, MSS-RE75, RE77, and Terry Turbine radiation monitor MSS-RE79. Actuations & their initiation signals: None. Causes: Preplanned electrical maintenance of radiation monitors power supplies. Effect of event on plant: Loss of assessment capabilities from radiation monitors used for EAL (Emergency Action Level) classification. Actions taken or planned: Maintenance of electrical power supplies to radiation monitors. Additional information: Radiation monitors will be removed from service for approximately 48 hours. The licensee has notified the NRC Resident Inspector and applicable state and local authorities. |