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| Entered date | Event description | |
|---|---|---|
| ENS 57004 | 3 March 2024 22:15:00 | The following information was provided by the licensee via email: On 3/3/24 at 1942 EST, while performing a plant shutdown in preparation for a refuel outage, Nine Mile Point Unit 2 experienced a reactor scram due to a main turbine trip on low condenser vacuum. The plant was at approximately 55 percent power at the time of the reactor scram. Additionally, following the scram a low RPV (reactor pressure vessel) level scram and containment isolation signal on level 3 was received, as expected. The containment isolation signal impacted RHR (residual heat removal) shutdown cooling, RHR letdown to radwaste, and RHR sampling. All impacted valves were closed at the time the isolation occurred. All control rods were fully inserted. Plant response was as expected. Post scram, the main turbine bypass valves are being used to control decay heat, and normal post scram level control is via the feed / condensate system. This is being report under 10 CFR 50.72(b)(2)(iv)(B), 'RPS Actuation', and 10 CFR 50.72(b)(3)(iv)(A), 'Specified System Actuation'. Unit 1 is not affected. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The cause of the low condenser vacuum was a momentary loss of sealing steam. The condenser remained viable for decay heat removal. All safety equipment is available. The grid is stable with the plant in its normal shutdown electrical configuration. |
| ENS 56089 | 4 September 2022 21:31:00 | The following information was provided by the licensee via fax: On September 4, 2022 with Unit 2 in Mode 3, an (Reactor Protection System) RPS actuation and Containment Isolation occurred on (Reactor Pressure Vessel) RPV Low Level (Level 3) of 159.3 inches due to issues with the normal feedwater level control system during plant cooldown. The RPS actuation occurred with control rods already inserted and a containment isolation on Level 3. The containment isolation signal impacted (Residual Heat Removal) RHR Shutdown Cooling, RHR letdown to radwaste, and RHR sampling. All impacted valves were closed at the time the isolation occurred. Operators took manual control of RPV level and restored level to the normal operating band shortly after the low level was received. This is being reported under 10CFR50.72(b)(3)(iv)(A) and 10CFR50.72(b)(3)(iv)(B). The NRC Resident Inspector was notified. |
| ENS 50216 | 20 June 2014 07:31:00 | At 0110 (EDT) on June 20, 2014, Nine Mile Point Unit 2 lost communication to the DRMS (Digital Radiation Monitor System Computer). The DRMS provides the Control Room alarm functions for Offgas Pretreatment Process Radiation Monitors 2OFG-CAB13A/13B and Cooling Tower Blowdown Effluent Radiation Monitor 2CWS-CAB157. Due to the loss of the Control Room alarm function, 2OFG-CAB13A, 2OFG-CAB13B, and 2CWS-CAB157 have been declared non-functional. Compensatory measures (i.e. collect and analyze grab samples) have been implemented per the requirements of the Offsite Dose Calculation Manual (ODCM). The non-functional radiation monitors are necessary for accident assessment and are credited for Emergency Action Level (EAL) classification. The inability to classify an EAL due to the out of service radiation monitors is considered a loss of assessment capability per 10 CFR 50.72(b)(3)(xiii). The NRC Resident Inspector has been notified. The licensee has notified the State.
At 1208 (EDT) on June 21, the DRMS was declared functional. With the alarm functions restored, radiation monitors 2OFG-CAB13A, 2OFG-CAB13B, and 2CWS-CAB157 were declared functional and compensatory actions per the ODCM have been discontinued. The licensee notified the NRC Resident Inspector and the State of New York. Notified R1DO (Bickett). .. . . |
| ENS 50187 | 11 June 2014 00:23:00 | Nine Mile Point Unit 2 Secondary Containment was declared inoperable on 6/10/14 from 2032 EDT until 2036 EDT during the restoration of Reactor Building Ventilation System to a normal lineup. While performing actions to restore ventilation fans the Above Refuel Floor Exhaust Fan, 2HVR-FN5A, tripped when started resulting in building differential pressure becoming less negative than -0.25 inches. Tech Spec 3.6.4.1 Secondary Containment, Action A.1 to restore within 4 hours was entered at 2032 EDT on 6/10/14. The standby Above Refuel Floor Exhaust Fan, 2HVR-FN5B, was started per procedure and building differential pressure was restored. Secondary Containment was declared operable at 2036 EDT on 6/10/14 and Tech Spec 3.6.4.1 action was exited. Secondary containment being inoperable is a 8-hour report for 10 CFR 50.72(b)(3)(v)(c), 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 control the release of radioactive material. The licensee has notified the NRC Resident Inspector and will notify the State of New York. |
| ENS 49996 | 4 April 2014 08:58:00 | Nine Mile Point Unit 2 Ventilation Wide Range Gaseous Monitoring System was removed from service on 4/1/2014 at 1140 EDT to support isolation of the Unit 2 Reactor Building Ventilation during a Division 2 electrical bus outage. The monitoring system will be out of service for greater than 72 hours due to the planned maintenance window. NMP2 is in Mode 5, refueling. Compensatory actions remain in effect in accordance with the Off-Site Dose Calculation Manual. Expected return to service is 4/5/14. This event is being reported in accordance with 10 CFR 50.72 (b)(3)(xiii) due to a loss of assessment capability. The licensee notified the NRC Resident Inspector. |
| ENS 47547 | 23 December 2011 03:03:00 | This 60-day telephone notification is being made per the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation signal affecting containment isolation valves in more than one system. On November 7, 2011, Nine Mile Point Unit 2 (NMP2) received a Division 2 reactor building pipe chase high ambient temperature isolation signal, which resulted in closure of isolation valves in the reactor water cleanup (RWCU) system, the reactor core isolation cooling (RCIC) system, and the residual heat removal (RHR) system (isolation valve groups 5, 6, 7, and 10). All affected isolation valves responded as designed. The Division reactor building pipe chase high ambient temperature isolation signal was generated by a new NUS/Scientech ambient temperature indicating switch that had recently been installed as a replacement for the original Riley temperature switch, which is no longer being manufactured. Two temperature switches (one for Division 1 and one for Division 2) monitor the reactor building pipe chase area to detect a rise in area temperature, which is indicative of a leak in the RWCU, RCIC, or RHR system piping that exists in the area. At the time of the event, operations personnel confirmed that conditions requiring isolation of the RWCU, RCIC, and RHR systems did not exist, based on a check of the Division 1 reactor building pipe chase high ambient temperature channel and area radiation monitors. Therefore, the isolation signal was determined to be invalid. The NUS/Scientech temperature switch was subsequently removed and the original Riley temperature switch was re-installed. The apparent cause for generation of the trip signal from the new temperature indicating switch was determined to be the presence of signal noise that was not adequately filtered. This event was entered into the (Nine Mile Point) corrective action system as Condition Report (CR) 2011-010062. There were no safety consequences or impact on the health and safety of the public as a result of this event. The licensee notified the NRC Resident Inspector. |