ENS 44735: Difference between revisions
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| event date = 12/19/2008 18:31 EST | | event date = 12/19/2008 18:31 EST | ||
| last update date = 12/19/2008 | | last update date = 12/19/2008 | ||
| title = Automatic Reactor Scram Due | | title = Automatic Reactor Scram Due to Load Reject | ||
| event text = On December 19, 2008, at 1831 hours with the reactor at 100% core thermal power (CTP) an automatic reactor scram occurred. It appears the scram occurred as a result of a load reject experienced during a severe winter storm. Three of the four safety relief valves opened in response to the event. Primary Containment Isolation System (PCIS) Group 2 (sample valves) and Group 6 (reactor water cleanup system) and the reactor building isolation system (RBIS-secondary containment) isolated as designed (all have since been restored) on the reactor water level +12 inches setpoint due to normal vessel shrink. Initial review indicates all safety-related systems responded as designed. Off-site power has been maintained; however the two 4kv safety related buses (A5&A6) were conservatively placed on the station emergency diesel generators due to potential grid stability concern. Currently, the reactor mode select switch (RMSS) is in the Shutdown position; the reactor scram has been reset; the reactor is being maintained at approximately 940 psig, with pressure being maintained by the main turbine by-pass valves; and reactor water level is being maintained at normal levels of 29 inches with the main condensate and feedwater system. Station maintenance personnel are assessing the status of the station switchyard. Once this activity is complete the duration of the forced outage and recovery plans will be determined. | | event text = On December 19, 2008, at 1831 hours with the reactor at 100% core thermal power (CTP) an automatic reactor scram occurred. It appears the scram occurred as a result of a load reject experienced during a severe winter storm. Three of the four safety relief valves opened in response to the event. Primary Containment Isolation System (PCIS) Group 2 (sample valves) and Group 6 (reactor water cleanup system) and the reactor building isolation system (RBIS-secondary containment) isolated as designed (all have since been restored) on the reactor water level +12 inches setpoint due to normal vessel shrink. Initial review indicates all safety-related systems responded as designed. Off-site power has been maintained; however the two 4kv safety related buses (A5&A6) were conservatively placed on the station emergency diesel generators due to potential grid stability concern. Currently, the reactor mode select switch (RMSS) is in the Shutdown position; the reactor scram has been reset; the reactor is being maintained at approximately 940 psig, with pressure being maintained by the main turbine by-pass valves; and reactor water level is being maintained at normal levels of 29 inches with the main condensate and feedwater system. Station maintenance personnel are assessing the status of the station switchyard. Once this activity is complete the duration of the forced outage and recovery plans will be determined. | ||
All control rods fully inserted on the scram. | All control rods fully inserted on the scram. | ||
Latest revision as of 21:12, 1 March 2018
| Where | |
|---|---|
| Pilgrim Massachusetts (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-1.65 h-0.0688 days <br />-0.00982 weeks <br />-0.00226 months <br />) | |
| Opened: | Bruce Chenard 21:52 Dec 19, 2008 |
| NRC Officer: | John Knoke |
| Last Updated: | Dec 19, 2008 |
| 44735 - NRC Website
| |