ENS 42530
ENS Event | |
|---|---|
01:49 Apr 27, 2006 | |
| Title | Failure of Rps Signal to Initiate Reactor Trip |
| Event Description | At 2043 [CDT] on 4-26-06, during a plant shutdown with the reactor at approximately 35% power, the operating crew manually initiated a reactor trip. The operating crew had just stopped one of the two condensate pumps and then the remaining feedwater pump tripped unexpectedly. The operating crew recognized the turbine did not trip, as it is expected to automatically trip when no feedwater pumps are running. The automatic turbine trip would have automatically tripped the reactor. Therefore, the operating crew manually initiated a reactor trip.
Because the reactor did not automatically trip (i.e., failure of RPS to initiate and complete a reactor trip), the Shift Manager declared an Alert, at 2049, based on Chart F of Table 2-1 EPIP-AD-02. Therefore, this is a one-hour notification in accordance with 10CFR50.72(a)(1)(i) 'The declaration of any of the emergency classes specified in the licensee's approved Emergency Plan.' The manual reactor trip is reportable (4-hour) in accordance with 10CFR50.72(b)(2)(iv)(B) 'Any event or condition that results in an actuation of the Reactor Protection System (RPS) when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.' All systems functioned as expected following the manual reactor trip. Service Water Train B is inoperable because of a one-gallon per minute leak. All rods inserted fully. Decay heat is being removed with the steam dump and secondary PORVs. The condenser is losing vacuum due to the turbine trip. Auxiliary Feedwater Pumps started as required. The licensee notified the NRC Resident Inspector.
At 2049 on April 26, 2006, Kewaunee Power Station staff declared an Alert emergency classification (reference EN 42530). The Kewaunee Power Station staff has assessed this event. There was no affect on the health and safety of the general public and no release of radiation. No plant personnel were injured and the only plant equipment problem was with the failure of a trip of both feedwater pumps to cause the main turbine to trip. The Kewaunee Power Plant staff has conducted a preliminary investigation of the control room indications and sequential events recorder, which indicates that before the manual reactor trip there was no automatic reactor trip signal present and a failure of the reactor trip breakers did not occur. The Alert was terminated at 0024 CDT [on 04/27/06]. The unit is currently in the Hot Shutdown Mode with plans to cool the plant to less than 350 degrees Fahrenheit. The licensee notified the NRC Resident Inspector and will be notifying State and local government and issuing a press release. Notified NRR EO (MJ Ross-Lee), IRD Mgr (P. Wilson), R3DO (H. Peterson), DHS (Holz ), FEMA (Steindurf), NRC/EPA (Crews), DOE (Wyatt), USDA (Timmons), HHS (Peagler).
When performing a review of the event reported on April 26, 2006 (EN 42530), the Kewaunee Power Station staff determined another reporting criterion was met. An eight-hour report is required to be made per 10 CFR 50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of 10 CFR 50.72 except when the actuation results from and is apart of a pre-planned sequence during testing or reactor operation.' 10 CFR 50.72(b)(3)(iv)(B)(6) is PWR auxiliary or emergency feedwater system. As described in EN 42530, a manual reactor trip of the Kewaunee Power Station was initiated at 2043 on April 26, 2006. The manual reactor trip was initiated when the plant experienced a loss of both feedwater pumps. With a loss of both feedwater pumps and a manual reactor trip, the narrow range water level in both steam generators decreased to the actuation setpoint value for starting the Auxiliary Feedwater Pumps, causing all three Auxiliary Feedwater Pumps to start as designed. Because the steam generator water level was below the actuation setpoint, this was a valid actuation of the auxiliary feedwater system. As a valid actuation of the auxiliary feedwater system, this condition is reportable under 10 CFR 50.72(b)(3)(iv). The untimeliness of the report has been entered into the Kewaunee Power Station's corrective action program. The licensee notified the NRC Resident Inspector. Notified R3DO (H. Peterson). |
| Where | |
|---|---|
Kewaunee  Wisconsin (NRC Region 3) | |
| Reporting | |
| Emergency class: | Alert |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-3.17 h-0.132 days <br />-0.0189 weeks <br />-0.00434 months <br />) | |
| Opened: | Jonathan Robb 22:39 Apr 26, 2006 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Apr 27, 2006 |
| 42530 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A |
| Before | Power Operation (35 %) |
| After | Hot Standby (0 %) |
Kewaunee with 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 | |
WEEKMONTHYEARENS 466662011-03-10T21:49:00010 March 2011 21:49:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Inadvertant Opening a Substation Breaker Causing Loss of Station Power ENS 454382009-10-15T17:04:00015 October 2009 17:04:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Momentary Loss of Shutdown Cooling with Autostart of Emergency Diesel Generator ENS 431962007-02-28T05:33:00028 February 2007 05:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip During the Performance of a Surveillance ENS 430962007-01-12T16:39:00012 January 2007 16:39:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip/Reactor Trip ENS 429832006-11-10T20:20:00010 November 2006 20:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip at Low Power ENS 429472006-10-30T14:48:00030 October 2006 14:48:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip ENS 425302006-04-27T01:49:00027 April 2006 01:49:00 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 Failure of Rps Signal to Initiate Reactor Trip ENS 421732005-11-29T04:20:00029 November 2005 04:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Following Main Feed Pump Trip ENS 421692005-11-25T22:24:00025 November 2005 22:24:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Dangerous Levels of Carbon Dioxide Following a Cardox Release ENS 414252005-02-20T17:58:00020 February 2005 17:58:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Actuation on Steam Generator Low Level ENS 404892004-01-30T17:30:00030 January 2004 17:30:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event 2011-03-10T21:49:00 | |