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| Entered date | Event description | |
|---|---|---|
| ENS 44851 | 13 February 2009 17:00:00 | On February 13, 2009 at 1526 CST, Fort Calhoun Station declared a Notification of Unusual Event (NOUE) based upon EAL 4.2 - Both Diesel Generators NOT Operable. The station has entered Technical Specification 2.0.1(1) requiring the Unit to be placed in at least HOT SHUTDOWN within 6 hours. The cause of the NOUE is a potential common mode failure of the diesel generators. Design Engineering has identified an unanalyzed condition in which a High Energy Line Break in Room 81, Main Steam Lines Containment Penetration Room, or an auxiliary steam leak in Room 82, Turbine Building Ventilation Room, can potentially result in water entering both diesel generator rooms through the floor of Room 82 located directly above the diesel rooms, Rooms 63 and 64. This condition presents a potential common mode failure of the diesel generators due to loss of diesel generator auxiliaries from a single failure. The possibility of water leaking into Rooms 63, 64 and the Switchgear rooms prompted this declaration. Compensatory measures to exit the NOUE will be to remove auxiliary steam from room 82 and blockading shut the door between rooms 81 and 82. These actions are expected to be completed within one to three hours. The licensee notified the NRC Resident Inspector.
At 1828 CST, Fort Calhoun Station exited the Notification of Unusual Event. Both Diesel Generators were declared operable based upon establishing compensatory measures. Diesel 2 was confirmed operable by running in accordance with approved procedures. Diesel 1 was successfully run on February 11, 2009 per a monthly surveillance tests. No additional water intrusion had occurred into the diesel 1 room since completion of the surveillance test. Compensatory measures to prevent water intrusion into Room 82 include isolating auxiliary steam to room 82 to eliminate a source of water to room 82, installing a temporary barrier at the door between rooms 81 and 82 to prevent water from flowing from room 81 to room 82, should an HELB occur in room 81, and to open the door between room 81 and the turbine building to allow water to flow out of room 81 so as not to flow into room 82. Technical Specification 2.0.1 has been exited as of time 1828 CST. The licensee will notify the NRC Resident Inspector. Notified the R4DO (Miller), IRD (McDermott, McMurtray), DHS (Doyle), and FEMA (Via).
This is a retraction (of the report made under 10 CFR 50.72(b)(3)(ii)(B) - Unanalyzed Condition) Fort Calhoun has performed a detailed evaluation of water intrusion through cracks in the floor of room 82 above the emergency diesel generators, as identified in part in the notification of 2/13/2009. This evaluation determined that no common mode failure mechanism existed and that the diesel generators were capable of performing their design safety functions. The licensee informed the Resident Inspector. Notified R4DO (Rick Deese). |
| ENS 44833 | 5 February 2009 22:25:00 | At 1828 CST, a fire alarm in the Administration Building was reported to the Fort Calhoun Station Control Room. The Administration Building is located outside of the Protected Area on Owner Controlled Property. An Equipment Operator was dispatched to investigate the cause of the alarm. The Control Room entered AOP-06 Fire Emergency at 1830 CST. At 1832 CST, a report was received from a building occupant that smoke was emanating from a Mechanical Equipment Room located on the first floor of the building. At that time, personnel in the building attempted to extinguish the fire using a portable fire extinguisher but were unsuccessful. Local Fire Departments in the City of Blair and Fort Calhoun were dispatched. At 1840 CST, the Operator arrived at the scene, found light smoke coming from the Mechanical Equipment Room and proceeded to de-energize the ventilation equipment. At 1844 CST, the fire was then extinguished using portable fire extinguishers. It was at that time that Blair and Fort Calhoun Fire Companies arrived on site to assist. At 1911 CST, AOP-06 was exited. Preliminary investigation shows that filter media had become dislodged and contacted duct heaters in the ventilation system. The fire ignited secondary material in the area. The Protected Area of Fort Calhoun Station was not affected at any time during this incident. This event may cause heightened public or government concern related to the health and safety of on-site personnel. Therefore, this report is being made in reference to 10 CFR 50.72(b)(2)(xi). The licensee informed the NRC Resident Inspector and plans to issue a press release. |