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Start date | Reporting criterion | Title | Event description | System | LER | |
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ENS 42530 | 27 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 | 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). | Steam Generator Feedwater Service water Reactor Protection System Auxiliary Feedwater Main Turbine Emergency Feedwater System | |
ENS 42169 | 25 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 | At 16:09 CST, the Control Room received a fire alarm on the Main Generator and actuation of the fire protection system. The Main Generator is protected by Carbon Dioxide for fire protection purposes. There was no evidence of a fire at the Main Generator. Air sampling of the Cardox Storage Tank Room indicated Carbon Dioxide levels at life threatening levels. An Unusual Event was declared at 1624 CST based on Emergency Action Level Chart P 'External Events and Chemical Spills' for a release of toxic or flammable gas on site AND portable monitors indicate toxic or explosive concentrations at life threatening levels of the gas near the spill area. There were no personnel injuries reported and the licensee is conducting a survey to account for personnel. Ventilation of the affected areas is in progress to reduce the toxic gas levels. The licensee informed state/local agencies and the NRC Resident Inspector.
(The) declaration of Unusual Event has been terminated (at 1915 CST on 11/25/05). The Control Room received a fire alarm on the Main Generator and actuation of the fire protection system. The Main Generator is protected by Carbon Dioxide for fire protection purposes. There was no evidence of a fire at the Main Generator. (The) source of Carbon Dioxide gas has been isolated. The area with (the) life threatening concentration of Carbon Dioxide has been ventilated. (The) plant no longer has any areas with (a) toxic concentration of Carbon Dioxide at the life threatening levels. Normal plant operation continues. The licensee is continuing their investigation into the cause of the Cardox discharge. The licensee informed stat/local agencies and the NRC Resident Inspector. Notified R3DO(Skokowski), NRR (Gillespie), IRD (Leach), DHS (Akers) and FEMA (Ligett). | ||
ENS 40489 | 30 January 2004 17:30:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event | At 1151 CST, the licensee declared an Unusual Event per chart P. At approximately 1115 CST, while filling the CARDOX carbon dioxide (CO2) storage tank, the tank had reached the full mark and the operator requested the trucker to stop filling the tank. The operator verified tank filling had stopped and isolated the fill line at the tank. The operator then isolated the fill line at the truck bay. The fill line relief valve lifted, causing the vent line to bleed CO2 through a weep hole in the tank room. At 1140 CST, the shift manager was informed that CO2 levels in the tank room were at life threatening levels (40,000 ppm at floor level, 30,000 ppm at waist level). At 1155 CST, the shift manager was informed that CO2 concentration had decreased below life threatening levels. At 1215 CST, no further leakage of CO2 through the weep hole into the room was observed. At 1245 CST, CO2 levels in the CARDOX room and adjacent spaces had returned to at or near normal levels. At 1343 EST, the NRC decided not to enter Monitoring mode. The licensee notified the NRC senior resident inspector, along with state and local authorities.
At 1346 the Unusual Event was terminated by the licensee. CO2 levels in all areas of the plant have returned to normal working levels. The CO2 release was terminated at 1239 CST. Notified P. Louden, T. McGinty, T. Reis, FEMA, DHS (D. Lewis) |