Semantic search
| Discovered date | Reporting criterion | Title | Description | LER | |
|---|---|---|---|---|---|
| ENS 56637 | 25 July 2023 13:24:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Envelope Inoperable | The following information was provided by the licensee via email: At 0924 (EDT) on July 25, 2023, it was discovered that both trains of control room air conditioning system were simultaneously inoperable due to an inoperable control room envelope boundary. The boundary was restored at 0925 (EDT) on July 25, 2023. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. There has been no impact to Unit 3 which remains at 100% power.
The licensee determined in a subsequent engineering evaluation of the conditions that existed at the time, that the access hatch being open did not have an adverse impact upon the control room emergency ventilation system and the control room envelopes boundary's ability to perform their safety function including: Radiation dose to the occupants did not exceed the licensing basis, design basis accident calculated value. Protection of control room occupants from hazardous chemicals and smoke. Therefore, this condition is not reportable and NRC Event EN56637 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified R1DO (Lally) | |
| ENS 56620 | 12 July 2023 08:49:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | ECCS Potentially Inoperable | The following information was provided by the licensee via email: At 0449 (EDT) on 7/12/2023, Millstone Unit 3 declared the 'B' train of the emergency core cooling system (ECCS) inoperable due to a degraded damper associated with the ventilation support system for the 'B' charging pump. At the time of this event, the 'A' train of service water was already inoperable due to planned maintenance on a breaker that would have prevented an 'A' service water valve powered from this breaker from closing on a safety signal. This configuration resulted in the possibility that the 'A' train of ECCS would not have been available to fulfill its design function under all postulated accident conditions. This event is being reported under 10 CFR 50.72(b)(3)(v)(B), '(any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (B) remove residual heat).' Subsequently, the 'A' train of service water was restored to operable at 0548 on 7/12/2023. Repairs and investigation continue on the 'B' train ECCS damper. The NRC resident has been notified. This event did not impact Millstone Unit 2. There was no impact to the public.
The following information was provided by the licensee via email: The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(B), via an 8-hour report as an event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat. A subsequent engineering review of the conditions that existed at the time determined that, based on area temperature response, any impact on ventilation flows into and out of the `B' charging pump cubicle did not generate an observable change in the temperature trend. Based on this, it is concluded with reasonable assurance that the functional requirement of the support system was maintained and the `B' charging pump would have continued to perform its safety function until the `A' train of service water was restored to operable and as a result safety function was not lost. Therefore, this condition is not reportable and NRC Event Number 56620 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector." Notified R1DO (Bicket). | |
| ENS 56610 | 6 July 2023 16:32:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition | The following information was provided by the licensee via email: On July 6, 2023, at 1232 EDT, while operating in Mode 1 at 100 percent power, the supply check valve from the number 2 steam generator to the turbine driven auxiliary feedwater pump was determined during troubleshooting that it is not able to perform its isolation function. This failure would have resulted in the blowdown of both steam generators during a main steam line break in the number 2 steam generator main steam line upstream of the main steam isolation valves until the operators could isolate the faulted steam generator. Previous evaluation has determined that this condition constituted an unanalyzed condition that could impact containment pressure. There was no radioactive release to the environment. The steam line from the steam generator to the turbine driven auxiliary feedwater pump was isolated by use of a motor operated valve in the discharge line of the number 2 steam generator. There was no impact to Unit 3 which remains at 100 percent power. The NRC Senior Resident Inspector was notified. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. | |
| ENS 56544 | 30 May 2023 08:46:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Reactor Trip | The following information was provided by the licensee via email: At 0446 EDT on 5/30/2023, with Millstone Power Station Unit 3 operating at approximately 100 percent reactor power, an automatic reactor trip occurred due to a turbine trip caused by electrical protection. The reactor trip was uncomplicated and decay heat is being removed via steam dumps to the condenser. All systems responded as expected to the trip. Auxiliary feedwater actuated automatically as expected following the trip due to low-low levels in the steam generators. There was no risk to the public. There was no impact to Millstone Unit 2. This event is being reported as a four hour report under 10CFR50.72(b)(2)(iv)(B) as a condition that resulted in actuation of the reactor protection system while the reactor was critical, and as an eight hour report under 10CFR50.72(b)(3)(iv)(A) and 10CFR50.72(b)(3)(iv)(B) for actuation of the auxiliary feedwater system. The NRC Resident Inspector has been notified. | |
| ENS 55893 | 11 May 2022 01:21:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Report | The following information was provided by the licensee via email: A licensed operator had a confirmed positive for alcohol during a follow-up fitness-for-duty test. The employee's access to the plant is on hold in accordance with the licensee's fitness-for-duty policy. The licensee notified the NRC Resident Inspector. | |
| ENS 55576 | 14 November 2021 16:50:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | NON-FUNCTIONAL Steam Supply Check Valve to Turbine Driven Auxiliary Feedwater Pump | On November 14, 2021, at 1150 EST, while operating in Mode 1 at 100 percent power, the supply check valve from the Number 2 steam generator to the turbine driven auxiliary feedwater pump was determined during troubleshooting that it is not able to perform its isolation function. This failure would have resulted in the blowdown of both steam generators during a main steam line break in the Number 2 steam generator main steam line upstream of the main steam isolation valves until the operators could isolate the faulted steam generator. Previous evaluation has determined that this condition constituted an unanalyzed condition that could impact containment pressure. There has been no radioactive release to the environment. The steam lines from the steam generators to the turbine driven auxiliary feedwater pump have been isolated by use of a motor operated valve in the discharge line of the Number 2 steam generator. There has been no impact to Unit 3 which remains at 100 percent power. The NRC Senior Resident has been notified. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. | |
| ENS 55565 | 6 November 2021 15:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Steam Supply Check Failure to Turbine Driven Auxillary Feedwater | During a Unit 2 refueling outage valve overhaul activity on the steam supply check valve from the number 2 steam generator to the turbine driven auxiliary feedwater pump, 2-MS-4B, the check valve was found with its disc separated from the disc arm. This failure would have resulted in the blowdown of both steam generators during a main steam line break in the steam generator number 2 main steam line upstream of the main steam isolation valves until the operators could isolate the faulted steam generator. On November 6, at approximately 1100 EDT evaluation determined that this condition constituted an unanalyzed condition that could impact containment pressure. There has been no radioactive release to the environment. The valve has been repaired. The check valve in the steam supply from the number 1 steam generator to the turbine driven auxiliary feedwater pump was inspected and found to be satisfactory. There has been no impact to Unit 3 which remains at 100% power. The Senior Resident has been notified. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. | |
| ENS 54988 | 8 November 2020 13:29:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Due to Earthquake Felt Onsite | Millstone Units 2 & 3 declared an Unusual Event at 0921 EST after an earthquake was felt onsite. The earthquake monitoring instrumentation did not actuate, and there were no station system actuations. No damage has been detected at this time. Millstone has initiated their Abnormal Operating Procedure for an earthquake and performing station walkdowns. The State of Massachusetts has been notified. The Waterford Police and U.S. Coast Guard have contacted the station. The NRC resident has been notified. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
At 1510 EST on November 8, 2020, Millstone Units 2 & 3 exited the Unusual Event due to the earthquake following plant walkdowns that revealed no damage to plant structures, systems, or components. Station and System walkdowns identified no issues due to the earthquake. Millstone notified the State and local authorities, and the NRC Resident Inspector. Notified R1DO (DeFrancisco), IRD (Grant), NRR (Nieh), R1RA (Lew), NRR EO (Miller), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email). | |
| ENS 55026 | 7 November 2020 00:08:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of an Invalid Specified System Actuation | This 60-day telephone notification is being submitted in accordance with paragraphs 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A) to report an invalid actuation of the 'B' train High Head Safety Injection Pump (3SIH*P1B), the 'B' train Low Pressure Safety Injection Pump (3RHS*P1B) and four Steam Generator Blowdown Containment isolation valves at Millstone Nuclear Power Station Unit 3. At 1908 EST on November 6, 2020, with Unit 3 in Mode 3, a partial invalid actuation of 'B' train Emergency Core Cooling System (ECCS) components occurred. The 'B' train SIH pump and the 'B' train RHS pump had started, and ran successfully on recirculation. Four Steam Generator Blowdown Containment isolation valves also closed. Due to this condition the 'B' Emergency Diesel Generator and the 'B' Emergency Generator Load Sequencer (EGLS) were declared inoperable and the required Technical Specification action statements were entered. Troubleshooting determined that this actuation was caused by a failure of one of the circuit boards in the 'B' train EGLS that caused a partial 'B' train 'SIS only' signal. Other 'B' Train components received the 'SIS only' signal but did not start because they were already running or were a backup to an already running component. Troubleshooting discovered a failed NAND gate on the 'B' Train EGLS XA93 circuit card. The card was replaced, retested, and the Technical Specification action statements were exited. The pumps and valves responded in accordance with plant design. No other equipment was affected during this event. There were no safety consequences or impacts on the health and safety of the public. The event was entered into the station's corrective action program. The actuation was not due to actual plant conditions or parameters meeting design criteria for an ECCS actuation. Therefore, this is considered an invalid actuation. The NRC Resident Inspector was notified. | |
| ENS 54927 | 2 October 2020 13:45:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Inoperable | At 0945 hours (EDT) on 10/02/2020, with Millstone Unit 3 in Mode 4, Operations discovered a door in the Secondary Containment boundary blocked open. Investigation determined the door was blocked open at 1842 (EDT) on 10/01/2020, rendering Secondary Containment inoperable. The door was closed at 1002 ((EDT) on 10/02/2020), restoring Secondary Containment to operable status. Since Secondary Containment was rendered inoperable, Dominion Energy is reporting this as a condition that could have prevented the fulfillment of the safety function to control the release of radioactive material and mitigate the consequences of an accident. This condition is being reported as an eight hour report pursuant to 10 CFR 50.72 (b)(3)(v)(C) and (D). There was no release of radioactivity to the public. The NRC Senior Resident Inspector has been notified. With the door blocked open, the plant was in a 24-hour shutdown action statement. The state of Connecticut and local towns were notified. | |
| ENS 54816 | 4 August 2020 21:45:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | EN Revision Imported Date : 8/20/2020 BOTH SERVICE WATER HEADERS DECLARED INOPERABLE On 8/4/20, at 1745 EDT, Millstone Unit 2 entered technical specification (TS) 3.0.3 due to both service water headers being declared inoperable because strainer differential pressures (D/Ps) were greater than 9 psid. The high service water strainer D/P was the result of heavy debris impingement caused by tropical storm Isaias. To reduce heat loads and service water flow, Unit 2 reduced power to 75 percent. One service water header was restored to operable at 1816 EDT, at which time TS 3.0.3 was exited. At 1843 EDT both service water headers were declared operable. The NRC Resident Inspector has been notified.
The purpose of this call is to retract a report made on August 4, 2020, NRC Event Number EN 54816 describes a condition at Millstone Power Station Unit 2 (MPS2) in which both trains of service headers were declared inoperable due to service water strainer differential pressures greater than 9 psid. The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(A), (B) and (D) via an 8 hour prompt report as an event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to shutdown the reactor and maintain it in a safe shutdown condition, remove residual heat and mitigate the consequences of an accident. Upon further review, MPS2 determined that there was no loss of safety function. An engineering evaluation supports the conclusion that a strainer differential pressure of 16 psid would not challenge the system flow distribution during worst case conditions. The evaluation also demonstrates that flowrates on both headers were observed to be unaffected during the timeframe of the high strainer differential pressure conditions. Therefore, both service water headers would have provided the required flows to perform their safety function. Therefore, this condition is not reportable and NRC Event Number EN 54816 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified R1DO (Greives). | ||
| ENS 54738 | 5 June 2020 07:20:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | EN Revision Imported Date : 10/6/2020 CONTROL ROOM BOUNDARY DOOR FAILURE On June 5, 2020, at 0320 (EDT) a loss of control room envelope (CRE) was declared inoperable due to failure of door 204-36-007. The door was repaired at 0322 (EDT), restoring the CRE to operable. The NRC Resident Inspector, state, and local authorities were notified.
The purpose of this call is to retract a report made on June 5, 2020, NRC Event Number EN54738. NRC Event Report number EN54738 describes a condition at Millstone Power Station Unit 2 (MPS2) in which a control room envelope boundary door was discovered to not be able to fully close due to the latching mechanism being stuck in the extended position. The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(D) via an 8 hour prompt report as an event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. Upon further review, MPS2 determined that there was no loss of safety function. An engineering evaluation determined that even with the control room boundary door unable to be fully closed due to the latching mechanism being stuck in, the extended position, control room air in-leakage would not have been sufficient to prevent the control room emergency ventilation system from performing its safety function. Therefore, this condition is not reportable and NRC Event Number EN54738 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified R1DO (Dimitriadis).
The purpose of this call is to provide an update to the retraction for a report made on June 5, 2020, NRC Event Number EN54738. The retraction being updated was made on 7/9/2020 at 1443 hours. NRC Event Report number EN54738 describes a condition at Millstone Power Station Unit 2 (MPS2) in which a control room envelope boundary door was discovered to not be able to fully close due to the latching mechanism being stuck in the extended position. The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(D) via an 8 hour prompt report as an event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident (the Control Room Envelope). A subsequent engineering evaluation of the conditions that existed at the time, determined that the inability of the control room boundary door to fully close due to the latching mechanism being stuck in the extended position did not have an adverse impact upon the ability of the CRE to perform its safety function. The CRE remained operable throughout this event, and the ventilation system would have performed its safety function. Therefore, this condition is not reportable and NRC Event Number EN54738 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified R1DO (Lally). | ||
| ENS 54663 | 13 April 2020 19:50:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Trip Due to Low Condenser Vacuum | At 1550 EDT on 4/13/2020, with Millstone Power Station Unit 3 operating at approximately 82 percent reactor power, an automatic reactor trip occurred following a turbine trip due to low condenser vacuum caused by the trip of multiple circulating water pumps. Due to the loss of the circulating water pumps, decay heat removal was established by the steam generator atmospheric dump valves. All other systems responded as expected to the trip. Auxiliary feedwater actuated automatically as expected following the trip due to low-low levels in the steam generators. There was no risk to the public. There was no impact to Millstone Unit 2. The Senior Resident Inspector has been informed. This event is being reported as a four hour report under 10 CFR 50.72(b)(2)(iv)(B) as a condition that resulted in actuation of the reactor protection system while the reactor was critical, and as an eight hour report under 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72(b)(3)(iv)(B) for actuation of the auxiliary feedwater system. The licensee also notified the state of Connecticut, the Connecticut Department of Energy and Environmental Protection, and the city of Waterford. | |
| ENS 54631 | 1 April 2020 20:25:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Trip Due to Circuit Fault | On April 1, 2020, at 1625 EDT, Milllstone Unit 3 was in Mode 1, at 100 percent power, when an automatic reactor trip occurred following a main generator trip. The cause was due to a circuit fault between the main generator breaker and the offsite switchyard. The reactor trip was not complicated and the reactor remains stable in Mode 3. One of the two offsite electrical sources remain inoperable with an investigation of the circuit fault underway. Decay heat removal is maintained by the main condenser. There was no effect on Unit 2. The NRC Resident Inspector was notified. The licensee notified State and local government agencies. | |
| ENS 54457 | 27 December 2019 12:04:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Trip Due to Feedwater Pump Trip | This is a synopsis of initial information received via phone: On December 27, 2019, at 0705 EST, while Unit 2 was at 100 percent (Mode 1), the 'A' Main Feedwater Pump tripped due to an unknown cause. The reactor was manually tripped and is currently at zero (0) percent power (Mode 3). Decay heat is being removed via Auxiliary Feedwater. The 'B' Feedwater pump is operable. There was no impact on Unit 3. The licensee notified the NRC Resident Inspector. Additionally, Connecticut Department of Environmental Protection, Waterford Dispatch, and East Lyme Emergency Management Division will be notified.
This is an update to NRC Event Number 54457. At 0704 EST, on 12/27/2019, with Millstone Unit 2 operating at 100 percent power, operators inserted a manual reactor trip. The trip was initiated due to a trip of the 'A' Main Feedwater Pump. The Auxiliary Feedwater System (AFW) automatically actuated as required. All control and shutdown rods fully inserted. All safety systems responded as designed. No primary or secondary safety valves actuated during or after the transient. Unit 2 is currently stable at normal operating pressure and temperature in Mode 3, Hot Standby. Reactor Coolant System (RCS) temperature is being maintained by the steam dump system with all Reactor Coolant Pumps (RCPs) in service. Main Feedwater has been secured, and Auxiliary Feedwater is in service. The electrical system is in normal alignment. There was no impact on Unit 3. There was no impact to the health and safety of the public or plant personnel. Due to Reactor Protection System (RPS) actuation while critical, this event was reported as a four hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B); and an eight hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of the AFW system. The licensee will notify the NRC Resident Inspector of the update. Notified R1DO (Cherubini). | |
| ENS 54449 | 18 December 2019 00:29:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Technical Specification Required Shutdown | At 1929 EST, on 12/17/19, Millstone Unit 3 began preparations for shutting down the reactor as the 'A' Emergency Diesel Generator (EDG) could not be restored to operable status within the 14-day outage time, requiring a Technical Specification (Tech Spec) shutdown. Per Tech Spec 3.8.1.1., the reactor must be in Hot Standby in six (6) hours, and Cold Shutdown within the following 30 hours. Hot Standby is estimated by midnight, and Cold Shutdown by 1800 EST on 12/18/19. All other safety and shutdown systems are operable. Decay heat removal will be through the Shut Down Cooling and Residual Heat Removal systems. There was no impact to Unit 2. There was no impact to the health and safety of the public or plant personnel. The licensee notified the state of Connecticut, Waterford County, and the NRC Resident Inspector. | |
| ENS 53752 | 25 November 2018 01:15:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | En Revision Imported Date 1/22/2019 | EN Revision Text: LOSS OF CONTROL ROOM ENVELOPE DUE TO DOOR FAILURE On 11/24/18 at 2015 EST, a loss of Control Room Envelope (CRE) was declared due to failure of the control room boundary door, 204-36-008. (Abnormal Operating Procedure 8588A Mitigating Actions for Control Boundary Breach was implemented). The door was repaired at 2030 EST, restoring CRE to operable (status). A mechanical failure of the control room door latch prevented the door from closing. The licensee notified the NRC Resident Inspector.
The purpose of this call is to retract a report made on November 25, 2018, NRC Event Number EN53752. NRC Event Report number EN53752 describes a condition at Millstone Power Station Unit 2 (MPS2) in which a control room envelope boundary door was discovered to not be able to fully close due to the latching mechanism being stuck in the extended position. The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(D) via an 8-hour prompt report as an event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. Upon further review, MPS2 determined that there was no loss of safety function. An engineering evaluation determined that even with the control room boundary door unable to be fully closed due to the latching mechanism being stuck in the extended position, control room air in-leakage would not have been sufficient to prevent the control room emergency ventilation system from performing its safety function. Therefore, this condition is not reportable and NRC Event Number EN53752 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified the R1DO (Carfang). | |
| ENS 53688 | 22 October 2018 04:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Inoperable Control Room Envelope Due to Failed Surveillance | On October 22, 2018 at 2241 hrs. EDT, a loss of Control Room Envelope (CRE) was declared due to failing to meet the requirements of (surveillance requirement) SR 4.7.6.1h during 72-month surveillance testing. Measured in-leakage exceeded the SR acceptance value. Abnormal Operating Procedure 2588A, 'Mitigating Actions for Control Room Envelope Boundary Breach', have been implemented. The licensee has notified Connecticut Department of Environmental Protection, Connecticut dispatch, Waterford dispatch, and the NRC Resident Inspector of this event. | |
| ENS 53533 | 2 August 2018 04:00:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Release of Possible Tritium Bearing Water | The following was received via telephone and email notification from Millstone Power Station: Millstone Power Station Unit 3, identified that the underground pipe to the Condensate Surge Tank had leaked greater than 100 gallons of water that included trace amounts of tritium to the ground. The effected piping is inside the protected area and has been isolated and drained. No tritium has been detected in any monitoring wells outside of the Protected Area. There is no threat to employees or the public or impact to drinking water. The Connecticut Department of Energy and Environmental Protection, and the towns of Waterford and East Lyme were notified at approximately 1300 (EDT) on August 2, 2018. The licensee notified the NRC Resident Inspector. | |
| ENS 53428 | 27 May 2018 02:01:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Spurious Siren Actuation | County and state governments were notified due to the spurious actuation of a single emergency notification siren located in New London County in the Town of Lyme. The siren was silenced. If required, alternate notification of the public in the area will be through local Emergency Operations Center route alerting. The NRC Resident Inspector has been notified. | |
| ENS 53328 | 12 April 2018 15:18:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness-For-Duty Report Involving Discovery of Kombucha Tea Inside the Protected Area | At 1148 EDT on April 12, 2018, a 16.2 ounce bottle of Kombucha tea was found in a small refrigerator in the Administration Building inside the Protected Area. The bottle was found to have a small amount missing from the contents. Kombucha tea is a fermented tea containing trace amounts of alcohol, and is legally sold without restrictions. Dominion Energy Nuclear Connecticut had previously notified its workforce that Kombucha tea was prohibited from being consumed or carried onsite. The owner has not yet been determined. This is considered an alcoholic beverage and is being reported pursuant to the requirements of 10 CFR 26.719 as a 24 hour report. The NRC Resident Inspector, the State of Connecticut, and local authorities have been notified. | |
| ENS 53229 | 25 February 2018 08:30:00 | 10 CFR 26.719, FFD Reporting requirements | Violation of Fitness for Duty Policy | A non-licensed employee was found in violation of the sites Fitness for Duty Policy. The employee's access authorization to the plant has been terminated. The NRC Resident Inspector has been notified. | |
| ENS 53005 | 9 October 2017 18:05:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event - Flammable Gas in the Turbine Building | While troubleshooting a hydrogen differential pressure gauge, operators found a hydrogen concentration greater than the lower explosive limit (4% hydrogen concentration). The licensee evacuated the turbine building. The licensee is ventilating the area to allow personnel access to isolate and repair the leak. The plant Fire Brigade is on standby. This event was declared for GU-2: release of toxic or flammable gas. The main generator pressure and hydrogen concentration are stable. The licensee notified the NRC Resident Inspector. Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
The unusual event was terminated at 1617 EDT because the leak was isolated and the hydrogen concentration in the Hydrogen Control Cabinet was zero percent. The licensee notified the NRC Resident Inspector. Notified the R1DO (Jackson), IRD MOC (Stapleton), NRR (King), DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email). | |
| ENS 52948 | 6 September 2017 15:15:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Potential Release of Tritium Bearing Water and Secondary Chemicals Into the Protected Area | Inspection of an underground pipe used to discharge the contents of the Unit 3 Condensate Polishing Facility in accordance with the National Pollutant Discharge Elimination System (NPDES) Discharge Permit identified the potential for small amounts of water containing tritium and Secondary chemicals to be released to the ground within the plant Protected Area. The water met all permit limits for discharge to the normal discharge point. Groundwater tritium levels were well below reportable limits. The line has been removed from service. The Connecticut Department of Energy and Environmental Protection was notified at 1115 (EDT) on September 6, 2017. This event is being reported in accordance with 10CFR50.72(b)(2)(xi) for 'Any event or situation, related to the health and safety of the public or onsite personnel, or protection of the environment, for which a news release is planned or notification to other government agencies has been or will be made. | |
| ENS 52904 | 15 August 2017 11:48:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Due to Fire Alarm in Containment | On August 15, 2017 at 0748 EDT, an Unusual Event was declared at Millstone Unit 2 due to a fire alarm indication in containment that was unable to be verified extinguished within 15 minutes. Current containment parameters do not indicate an actual fire. A containment entry is planned to verify that there is no fire. Unit 2 continues at 100% power. Unit 3 was unaffected. The NRC remains in Normal mode. The licensee notified the NRC Resident Inspector and State and local government agencies. Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail.
At 0951 EDT, the Unusual Event was terminated. No signs of an actual fire were present upon containment entry. All alarms are cleared and they are investigating the cause of the alarm. The licensee notified the NRC Resident Inspector and State and local government agencies. Notified R1DO (Gray), NRR EO (Miller), and IRD (Gott). Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail. | |
| ENS 52501 | 20 January 2017 13:35:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Failure of a Secondary Containment Door to Close | At 0835 (EST) on January 20, 2017, at Millstone Power Station Unit 3, subsequent to personnel passage through a door in the auxiliary building, the door failed rendering it unable to completely close. At this time, in accordance with Technical Specification 3.6.6.2 "Secondary Containment," the Shift Manager declared the secondary containment inoperable. The door was repaired and the door completely closed at 1256 (EST) on January 20, 2017, and secondary containment was declared operable. Since Secondary Containment was rendered inoperable, Dominion is reporting that this condition could have prevented the fulfillment of the safety function to control the release of radioactive material and mitigate the consequences of an accident. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72(b)(3)(v)(D). The NRC Senior Resident Inspector has been notified. | |
| ENS 52169 | 11 August 2016 13:59:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Trip Due to Loss of Two Circulating Water Pumps | Reactor operators manually tripped the reactor due to the loss of two out of four circulating water pumps which caused a drop in condenser vacuum. The trip was uncomplicated. The reactor is shutdown and stable with decay heat removal via steam dumps to the condenser. The cause of the circulating water pump trips is currently unknown, but initial indications are that the pumps tripped due to a lightning strike that caused an electrical perturbation. The reactor will remain shutdown while the licensee investigates the cause. Unit 3 was not affected. The licensee notified the NRC Resident Inspector and the State and Local governments. | |
| ENS 51929 | 15 May 2016 10:38:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unusual Event Due to Main Generator Hydrogen Leak in Turbine Building | At 0638 EDT on 5/15/2016, an Unusual Event (EAL GU.2) was declared on Millstone Unit 3 due to a Main Generator hydrogen gas leak into the Turbine Building. At 0645 EDT, operators manually tripped the reactor. All rods inserted. All systems functioned as expected following the reactor trip. Operators are currently venting the remaining hydrogen from the generator through the normal vent path. There is no safety related equipment out-of-service. The plant is in a normal post-trip electrical line-up. All Emergency Diesel Generators are available. The licensee notified the State of Connecticut and the NRC Resident Inspector. Notified DHS SWO, FEMA Ops Center, and DHS NICC Watch Officer. Notified via E-mail FEMA National Watch Center and NuclearSSA.
At 0949 EDT, the licensee terminated the Unusual Event. At 0645 EDT on 5/15/16, a manual reactor trip was initiated at Millstone Unit 3 due to a hydrogen leak from the main generator. As expected, Auxiliary Feedwater System (AFW) initiated on the reactor trip. The trip was uncomplicated and the plant is currently in Mode 3 with a normal electric lineup and decay heat is being removed via steam dumps to the condenser. The cause of the hydrogen leakage is under investigation. This is reportable under 10 CFR 50.72(b)(2)(iv)(B) - RPS actuation while critical, and 10 CFR 50.72 (b)(3)(iv)(A) - valid specified system actuation. The licensee has notified Waterford Township, the State of Connecticut and the NRC Resident Inspector. Notified R1DO (Burritt), NRR ET (McDermott), NRR EO (Morris), IRD (Grant), DHS SWO, FEMA Ops Center, DHS NICC, FEMA National Watch Center (email) and NuclearSSA (email). | |
| ENS 51889 | 28 April 2016 00:07:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Energy Line Break Door Discovered Open | On April 27, 2016 at 20:07 (EDT), a high energy line break (HELB) door between the turbine driven auxiliary feedwater pump and the motor driven auxiliary feedwater pump rooms was discovered open and unattended. In the event of a HELB, this condition could have rendered both trains of auxiliary feedwater inoperable. The boundary was not operable for approximately 1 hour. Upon discovery, the door was closed restoring the boundary. This event is being reported pursuant to 10 CFR 50.72(b)(3)(v) as any event or condition that alone could have prevented the fulfillment of the safety function of structures or systems that are needed to: (B) Remove residual heat; and (D) Mitigate the consequences of an accident. The NRC Senior Resident Inspector has been notified. The Licensee notified the Connecticut DEEP and Waterford Dispatch. | |
| ENS 51860 | 9 April 2016 19:23:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Secondary Containment Determined to Be Inoperable During Surveillance Testing | During pre-planned surveillance testing of the Supplementary Leak Collection and Release System (SLCRS), an issue was found affecting the Secondary Containment boundary. Millstone Unit 3 is being moved to Mode 5 for a refuel outage where investigation and repairs will be made. This is reportable under 10CFR50.72(b)(3)(v)(C), a condition that could have prevented the fulfillment of a safety function for systems or structures to control the release of radioactive material, and 10CFR50.72(b)(3)(v)(D) to mitigate the consequences of an accident. The surveillance testing was being performed while Millstone 3 was being removed from service for an upcoming Refueling Outage. The licensee has notified the NRC Resident Inspector and State and Local authorities. | |
| ENS 51682 | 25 January 2016 06:47:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip Due to Reactor Coolant Pump Trip | At 0147 EST on 1/25/16, the 'B' Reactor Coolant Pump (RCP) tripped offline. This caused a reactor trip on low coolant flow. As expected, the Aux Feedwater System (AFW) initiated on the reactor trip. The trip was uncomplicated and the plant is currently shutdown in Mode 3 with a normal electrical lineup and decay heat is being removed via steam dumps to the condenser. The cause of the 'B' RCP trip is under investigation. A containment entry is planned for dayshift on 1/25/16 to inspect and troubleshoot the 'B' RCP. The Licensee has notified the NRC Resident Inspector. | 05000423/LER-2016-001 |
| ENS 51632 | 3 January 2016 04:05:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification of Fish Kill | Millstone Unit 3 reported a non spill related environmental fish kill event with greater than 300 fish found in the trash basket. The cause of the fish kill is unknown at this time. The type of fish reported was Atlantic Menhaden. The NRC Resident Inspector has been notified. | |
| ENS 51521 | 8 November 2015 07:30:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Trip Due to Reactor Coolant Pump Oil Leak | During power ascension following refueling outage, a decreasing oil level in the 'C' Reactor Coolant Pump was noted. When the oil level reached 69 percent, with the reactor at approximately 56 percent rated thermal power, per plant procedure, a rapid downpower was initiated which brought the plant to approximately 15 percent power and a manual reactor trip was initiated at that point. The reactor trip was uncomplicated and all plant equipment responded as expected. The licensee notified the NRC Resident Inspector. | |
| ENS 51513 | 4 November 2015 16:33:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Fire on the 'A' Emergency Diesel Generator | At 1133 EST on 11/4/15, an Alert was declared due to a fire in the 'A' Emergency Diesel Generator (EDG) enclosure. Fire caused damage to the safety related EDG and was declared inoperable. The fire is out, and off-site assistance was not necessary. A fire watch has been stationed, and no personnel injuries were reported. The licensee has notified the NRC Resident Inspector. Notified DHS, FEMA, USDA, HHS, DOE, DHS NICC, EPA EOC, FEMA NWC (via email), FDA EOC (via email) and Nuclear SSA (via email).
At 1446 EST on 11/4/15, Millstone Unit 3 terminated the Alert declaration following satisfactory atmospheric samples at the site boundary and notifying the State of Connecticut. The licensee will notify the NRC Resident Inspector. Notified R1DO (Rogge), NRR EO (Morris), and IRD (Grant). Notified DHS, FEMA, USDA, HHS, DOE, DHS NICC, EPA EOC, FEMA NWC (via email), FDA EOC (via email) and Nuclear SSA (via email). | |
| ENS 51448 | 4 October 2015 13:32:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Identified Rcs Leakage > 25 Gpm | 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. | |
| ENS 51351 | 26 August 2015 23:20:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Tree Branch Fell on Amtrak Power Line and Caused Brush Fire | A small brush fire occurred adjacent to an AMTRAK railroad right of way that passes through the Millstone Power Station owner controlled area, due to a downed tree branch that knocked down an AMTRAK electrified power line. The fire is outside the protected area of the site, and poses no public hazard or threat to building or structures. Outside assistance has been requested. Waterford Fire Department and AMTRAK have responded, and have eliminated the source and extinguished the fire. This report is being made pursuant of 10CFR50.72(b)(2)(xi). There is no radioactive release associated with this event. Dominion may respond to public inquiry, but no press release is planned. The NRC Resident Inspector has been notified. The Connecticut State Department of Energy and Environmental Protection and Waterford Dispatch were notified. | |
| ENS 51264 | 27 July 2015 00:25:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Unit 2 Site Stack Radiation Monitor Failure | The Millstone Site Rad Monitor, RM-8169, has failed and was declared NOT FUNCTIONAL at 2025 (EDT) on July 26, 2015. This is reportable pursuant to 10CFR50.72(b)(3)(xiii), as any event that results in a major loss of emergency assessment capability, off-site response capability, or off-site communication capability. I&C (Instrumentation and Control) is developing a troubleshooting and repair plan. The licensee notified the NRC Resident Inspector, the State of Connecticut Department of Energy and Environmental Protection, and the City of Waterford Dispatch. The loss of this radiation monitor is considered a major loss of assessment capability since it is used in Emergency Action Level (EAL) classification and there is no compensatory measure available. | |
| ENS 51187 | 28 June 2015 13:00:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Environmental Boundary Door Found Unlatched | During Security checks of Control Room doors, a boundary door was found not latched. This door is capable of being manually closed and latched. The door was in this condition for 4 hours and 25 minutes. The door is currently closed and latched. This is being reported as it could have prevented the fulfillment of a safety function to mitigate the consequences of an accident per 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector has been notified. A condition report has been written and the door is posted to require manual checks to ensure it is latched until the door closing mechanism is repaired.
Event Report number 51187 describes a condition at Millstone Power Station Unit 2 (MPS2) in which a control room environmental boundary door was found unlatched. This was reported in accordance with 10CFR 50.72(b)(3)(v)(D) as a condition that could have prevented the fulfillment of a safety function to mitigate the consequences of an accident. Upon further review, MPS2 has concluded that there was no loss of safety function, because even with the control room boundary door unlatched, the control room emergency ventilation system would have been able to perform its safety function during accident conditions. The MPS2 control room is pressure neutral and the hydraulic door closure mechanism was verified adequate to ensure the door would close and remain closed during accident conditions (even though it was not latching). Therefore, this condition is not reportable and NRC Event Number 51187 is being retracted. The basis for this conclusion will be provided to the NRC Resident Inspector. Notified the R1DO (Cahill). | |
| ENS 51161 | 17 June 2015 03:43:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Service Water Effluent Radiation Monitor Out of Service | The B train of the service water effluent radiation monitor failed at 2343 EDT and is being repaired. The licensee notified the NRC Resident Inspector.
The purpose of this call is to retract a report made on June 17, 2015, NRC Event Number 51161. Event Report number 51161 describes a condition at Millstone Power Station Unit 3 (MPS3) in which a service water radiation monitor failed, was taken out of service for repair and was reported in accordance with 10 CFR 50.72(b)(3)(xiii) as a loss of emergency assessment capability. Upon further review, MPS3 has concluded that the subject radiation monitor is not utilized for emergency assessment capability. Therefore, this condition is not reportable and NRC Event Number 51161 is being retracted. The basis for this conclusion will be provided to the NRC Resident Inspector. R1DO(Dimitriadis) have been notified. | |
| ENS 51149 | 11 June 2015 20:54:00 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Degraded Containment Spray Flow Check Valve | During containment spray pump inservice testing the minimum flow recirculation line recorded negative flow indicating reverse flow in the line. After the troubleshooting, it was determined that a degraded minimum flow check valve was allowing a path to the refueling water storage tank (RWST) for certain post loss of coolant accident (LOCA) conditions. The minimum flow isolation has been closed to eliminate the path. No actuation occurred during this time. The NRC Resident Inspector, Connecticut Department of Energy and Environmental Protection (DEEP) Hartford, and Watertown Dispatch have been notified.
The purpose of this call is to correct the record for the 10 CFR 50.72(b)(3)(v)(C) event report provided on June 11, 2015. Event report number 51149 states: 'During containment spray pump inservice testing ...' The condition of the degraded containment spray flow check valve was identified: 'During high pressure safety injection pump inservice testing...'." Notified R1DO (Bickett)
The purpose of this call is to update the record for the 10 CFR 50.72(b)(3)(v)(C) event report provided on June 11, 2015. During subsequent investigation, it has been determined that a second release path may have existed through ECCS system relief valves under certain post LOCA conditions as a result of the degraded check valve described in the original report. The licensee has informed the NRC Resident Inspector. Notified R1DO (Cahill). | |
| ENS 51035 | 3 May 2015 01:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Normal and Hi Range Ventilation Process Radiation Monitors Out of Service | Loss of assessment capability due to unplanned removal from service of a radiation monitor due to process flow monitor indication failing hi. The normal and hi range ventilation vent process radiation monitors (3HVR*RE10A/B are out of service. This condition was discovered during control room rounds. The condition is reportable per 10CFR50.72(b)(3)(xiii). Compensatory measures are in place. The licensee notified the NRC Resident Inspector and applicable State and Local authorities. | |
| ENS 50873 | 9 March 2015 13:57:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Millstone Unit 2 Site Stack Radiation Monitor Sample Pump Trip | On March 9, 2015 at 0957 EDT, the Millstone Site Stack Radiation Monitor RM 8169 sample pump tripped. This resulted in a loss of assessment capability. Compensatory measures have been put in place to provide chemistry sampling. The cause is under investigation and the Instrument & Controls Department is troubleshooting and repairing the sample pump. The NRC Resident Inspector, Connecticut Department of Environmental Protection, and the Town of Waterford have been notified. | |
| ENS 50842 | 22 February 2015 02:22:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Reactor Vessel Level Monitoring System Inoperable | The licensee declared the reactor vessel level monitoring system (RVLMS) inoperable when an intermittent failure occurred in the 'B' train reactor vessel level monitoring system (RVLMS) concurrent with the loss of the 19% level sensor in the 'A' train. This caused entry into a 7-day LCO action statement under Technical Specification 3.3.6, Action E. The 'B' train instrumentation was reset and indication returned to normal and the LCO action was exited after 36 minutes. A Condition Report was submitted to determine cause and repair, if needed. The licensee has notified the NRC Resident Inspector as well as state and local authorities. | |
| ENS 50841 | 22 February 2015 00:50:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Site Stack Radiation Monitor Failure | The Millstone site stack radiation monitor, RM-8169, failed and was declared inoperable at 1950 EST on February 21, 2015. Repairs are in progress. This event is reportable pursuant to 10 CFR 50.72(b)(3)(xiii) as any event that results in a major loss of emergency assessment capability, off-site response capability, or off-site communications capability. The Instrument and Controls Department is conducting troubleshooting and repair. The cause of the radiation monitor failure was sample pump failure. The licensee has notified the NRC Resident Inspector and applicable State and Local authorities. | |
| ENS 50797 | 9 February 2015 13:24:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Stack High Range Radiation Monitor Out of Service for Planned Maintenance | 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 50775 | 28 January 2015 13:49:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Site Stack Radiation Monitor Failure | The Millstone site stack radiation monitor, RM-8169, failed and was declared inoperable at 0849 EST on January 28, 2015. Repairs are in progress. This event is reportable pursuant to 10 CFR 50.72(b)(3)(xiii) as any event that results in a major loss of emergency assessment capability, off-site response capability, or off-site communications capability. The Instrument and Controls Department is conducting troubleshooting and repair. The cause of the radiation monitor failure was pump failure. Estimated return to service is 1600 EST on 1/29/15. The licensee has notified the NRC Resident Inspector and applicable State and Local authorities. | |
| ENS 50767 | 26 January 2015 21:50:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Turbine Building Stack Ventilation Radiation Process Monitors Removed from Service | Normal and High Range Ventilation Process Radiation Monitors (3HVR*RE10A/B) were removed from service due to low process flow affecting sample flow. The cause of the low process flow is unknown and under investigation at this time. Maintenance was performed yesterday, 1/26/15, including a successful calibration. Action taken includes placing temporary sampling in service and estimating process flow. A priority one work package has been issued with repairs in progress. The licensee informed the State of Connecticut, Waterford Township Police and the NRC Resident Inspector. | |
| ENS 50836 | 20 January 2015 01:18:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | High Energy Line Break Boundary Door Not Latching | 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. | 05000423/LER-2015-001 |
| ENS 50737 | 15 January 2015 13:08:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | A&B Switchgear Room Boundary Door Latch Discovered Not Functioning Properly | On January 15, 2015 a high energy line break door affecting both trains of safety related switchgear rooms was discovered not latching after passage. The boundary was not operable for approximately 19 minutes. The door has been repaired. Dominion is reporting that this condition could have prevented the fulfillment of the safety function to mitigate the consequences of an accident pursuant to 10 CFR 50.72(b)(3)(v)(D). The NRC Senior Resident Inspector has been notified. The State of Connecticut Department of Energy, and Environmental Protection and Waterford Dispatch were also notified. | |
| ENS 50712 | 1 January 2015 23:25:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Main Control Room Boundary Door Did Not Properly Latch | During (surveillance) checks of Control Room doors, a boundary door did not latch after being accessed until the door was opened and closed. This is being reported as it could have prevented the fulfillment of a safety function to mitigate the consequences of an accident per 10CFR50.72(b)(3)(v)(D). The door is currently closed and latched. The door was in this condition for between 5 and 10 seconds. The licensee notified the Connecticut Department of Environmental Protection, Town of Waterford and the NRC Resident Inspector.
Upon further review, Millstone Power Station Unit 2 has concluded that there was no loss of safety function, because even with the control room door latch degraded, the control room door and its closing mechanism would still be able to maintain the control room envelope's boundary intact. Therefore, this condition is not reportable and NRC Event Number 50712 is being retracted. The basis for this conclusion will be provided to the NRC Resident Inspector. The licensee notified the NRC Resident Inspector. Notified R1DO (Jackson). |