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| Entered date | Event description | |
|---|---|---|
| ENS 51369 | 4 September 2015 12:58:00 | On September 4, 2015, at 0916 (EDT), Nine Mile Point Unit 1 experienced an automatic reactor scram following Main Steam Isolation Valve (MSIV) closure and isolation of both main steam lines. The cause of the MSIV closure is not known at this time. All control rods fully inserted. Following the scram, pressure was momentarily controlled through the use of the Emergency Condenser system. At 0950, pressure control was established through the main steam lines to the condenser through Main Steam Isolation Valves (MSIVs) 01-02 and 01-04. MSIV 01-03 would not reopen. All other plant systems responded per design following the scram. The reactor scram is a 4-hour report per 10 CFR 50.72(b)(2)(iv)(B)." The following systems automatically actuated after the scram as expected. These system actuations are an 8-hour report per 10 CFR 50.72(b)(3)(iv)(A). 1. The High Pressure Coolant Injection (HPCI) system. HPCI initiated at 0916 and reset at 0917 when RPV level was restored above the HPCI system low level actuation set point. HPCI initiated and was reset a second time at 0922. HPCI is a flow control mode of the normal feedwater systems, and is not an Emergency Core Cooling System. 2. The Core Spray system actuated, but did not discharge to the Reactor Coolant system. The Core Spray system was secured at 1033. 3. The Emergency Condenser (EC) system actuated to control pressure. EC-11 was secured at 0917. EC-12 was secured at 0921 . The maximum shell temperature of EC system was 193 degrees Fahrenheit. 4. Containment Isolation actuation. Nine Mile Point Unit 1 is currently in Hot Shutdown, with reactor water level and pressure maintained within normal bands. Since the scram, there have been no anomalies observed with feedwater system operation. Decay heat is being removed via steam to the main condenser using the turbine bypass valves. The offsite grid is stable with no grid restrictions or warnings in effect. The Reactor is being supplied by the normal feedwater system and there was indication of a partial lift/reset on one Electrometric Relief Valve (ERV). The licensee notified the NRC Resident Inspector and the State of New York Public Service Commission. |
| ENS 48097 | 12 July 2012 04:49:00 | On July 12, 2012, at 0200 EDT, clean steam reboiler 'B' failed, causing a loss of sealing steam. This resulted in degrading condenser vacuum and rising off gas system pressure. The main steam backup supply for sealing steam also failed, and condenser vacuum and off gas system pressure continued to degrade. In response to rising off gas system pressure and lowering condenser vacuum, reactor power was lowered to 85% in accordance with Special Operating Procedures. With off gas system pressure approaching the procedural limit and condenser vacuum degrading rapidly, a manual reactor scram was inserted at 0220 EDT. All control rods fully inserted and all systems functioned as expected on the scram. Plant is currently shutdown and parameters are stable. The unit is currently implementing post scram recovery procedures and plant cooldown is in progress. The cause of the loss of both the primary and backup sources of sealing steam is under investigation. The shutdown electrical lineup is normal and decay heat is being removed via steam bypass valves to the main condenser. The licensee has notified the NRC Resident Inspector and the Public Service Commission. |
| ENS 47141 | 11 August 2011 01:05:00 | NMP2 inserted a manual reactor scram due to a through wall leak on feedwater pump 2FWS-P1A minimum flow line. 2FWS-P1A has been removed from service to minimize the leak. All control rods inserted and all systems functioned as designed. The unit will remain in hot shutdown until plant startup. All systems functioned as required and the scram was uncomplicated. The licensee plans to issue a press release and has informed the NRC Resident Inspector and the New York State Public Service Commission.
The licensee will not be issuing a press release regarding this manual scram. R1DO (Powell) notified. |