ENS 44066
ENS Event | |
|---|---|
13:33 Mar 15, 2008 | |
| Title | Reactor Trip Due to Turbine Trip |
| Event Description | At 09:33 EDT the plant experienced a turbine trip which resulted in a reactor trip from 85%. Plant power was less than 100% due to a [turbine] control valve oscillating problem identified on 3/13/08.
Post-trip [complications]: one of the four 4160 V busses, Bus 1A1, did not fast transfer from 22 KV to the 161 KV system as expected. This buss loss caused Reactor Coolant Pump RC-3A [to] trip off. Seals on RC-3A appear to be failed. The other 3 RC pumps remained in service for forced circulation through the Steam Generators Steam Generator levels are being maintained by Main Feedwater Pump FW-4C. Steaming is through the steam dump and bypass valves to the condensers. No primary or secondary relief valves lifted during this event. Standard post-trip actions were taken per EOP-00 , followed by a transition to EOP-2. Loss of Off-Site Power. During EOP-00 the plant computer indicated 8 rods not inserted into the reactor core. Secondary and primary rod indication showed all control rods inserted. In response to the difference of rod position indication, emergency boration was implemented. Emergency boration was secured after shutdown margin was verified. 4160 V buss 1A was reenergized on the 161kv system at 10:31 EDT. A transition to plant procedure OP-3A, plant shutdown was made at 10:58 EDT. Reactor Coolant Pump RC-3A seal evaluation is in progress. The plant will remain in Mode 3. The licensee notified the NRC Resident Inspector and plans a press release. While RCP RC-3A seals indicate the same pressure across them there were no accompanying indications of containment sump water level increasing or high radiation levels in containment. Decay heat is being removed by normal feedwater feeding the steam generators steaming to the condenser steam dumps. Nuclear Instruments indicated plant shutdown throughout the trip. Safety buses are powered by offsite power and emergency diesel generators are in standby.
None of the reactor coolant pump seals at [Fort Calhoun Station] (FCS) were failed. There were abnormal indications on the A reactor coolant pump seal. The A reactor coolant pump seal is now working normally. Notified R4DO (Whitten). |
| Where | |
|---|---|
Ft Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation | |
| Time - Person (Reporting Time:+-2.23 h-0.0929 days <br />-0.0133 weeks <br />-0.00305 months <br />) | |
| Opened: | Kevin R. Boston 11:19 Mar 15, 2008 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Mar 17, 2008 |
| 44066 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (85 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 520332016-06-22T13:41:00022 June 2016 13:41:00
[Table view]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 Turbine Trip ENS 506882014-12-17T16:14:00017 December 2014 16:14:00 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 Loss of Load ENS 499262014-03-17T17:02:00017 March 2014 17:02:00 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 Turbine Trip Initiated by Loss of Stator Cooling Water ENS 497172014-01-12T09:23:00012 January 2014 09:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Following Control Rod Position Deviation ENS 465062010-12-23T16:50:00023 December 2010 16:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Uncomplicated Reactor Trip from 100% Power ENS 458282010-04-08T21:22:0008 April 2010 21:22:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Inoperable Steam Generator Inlet Isolation Valve ENS 440662008-03-15T13:33:00015 March 2008 13:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Due to Turbine Trip ENS 414462005-02-27T03:34:00027 February 2005 03:34:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Plant Had a Reactor Trip from 16.1% Power Due to a Loss of Turbine Load Signal ENS 401562003-09-13T01:55:00013 September 2003 01:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Unanticipated Negative Axial Shape Index (Asi). 2016-06-22T13:41:00 | |