Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 46934 | 7 June 2011 17:43:00 | Outside ambient air temperature exceeded the maximum analytical value for operability for Unit 1 D1 and D2 Diesel Generators at 1349 CDT. The calculated limiting outside air temperature needed for equipment in the D1 and D2 rooms to meet their temperature limits is 100.5?F. Outside ambient temperature exceeded this limiting value and both Unit 1 safeguards diesel generators were declared inoperable at 1349 CDT on 6/7/2011. If outside ambient air temperature is above the maximum analytical value, components within the D1 and D2 diesel rooms may not be able to perform their required functions thus preventing them from fulfilling their safety function needed to mitigate the consequences of an accident (10 CFR 50.72 (b)(3)(v)(D)). Unit 1 is currently in Mode 3, Hot Standby. Ambient outside air temperatures are at or near peak values for the day and expected to decrease approximately 1 to 2 degrees per hour which will restore ambient conditions to less than the maximum analytical value. The NRC Resident Inspector has been notified. The outside air temperature has peaked at 101.4?F which is unusually high for this location and is expected to drop below the 100.5?F limit shortly. The licensee does not anticipate that this condition will be repeated again any time soon.
An eight hour report (EN #46934) per 10 CFR 50.72(b)(3)(v)(D) was made on June 7, 2011 for outside ambient air temperature exceeding the maximum analytical value for operability for Unit 1 D1 and D2 Diesel Generators. Subsequent engineering analysis determined that D1 & D2 diesel generators would have performed their safety function with outside air temperatures of up to 102.5 degrees F. The outside air temperature did not reach 102.5 degrees F and the diesel generators were not inoperable. The 10 CFR 50.72(b)(3)(v)(D) report, EN #46934, is retracted. The NRC Resident Inspector has been notified. Notified R3DO (Giessner). |
| ENS 45077 | 18 May 2009 14:41:00 | Prairie Island Unit 1 experienced an automatic turbine and reactor trip following a lockout trip of (the) 12 Circulating Water Pump. Lockout of the circulating water pump resulted in a condenser A/B differential pressure trip of the main turbine which in turn caused an automatic reactor trip. Auxiliary Feedwater Pumps automatically started on low steam generator level. All control rods fully inserted. Decay heat removal is via auxiliary feedwater and condenser steam dump. Offsite power was maintained to safeguards and non-safeguards AC buses. Operations are in progress per Reactor Trip Response emergency procedures to stabilize plant conditions, restore main feedwater flow to the steam generators, and then shut down auxiliary feedwater pumps. The plant will then be maintained per normal shutdown procedures until the cause of the trip is corrected. No safety or relief valves lifted during the transient. There was no impact on Unit 2. The licensee notified the NRC Resident Inspector. |
| ENS 42565 | 10 May 2006 16:54:00 | This notification is being made in accordance with 10CFR50.72(b)2(xi) due to a press release being issued. The Nuclear Management Company (NMC) will be issuing a press release regarding maintenance activities on a non-safety related, non-radioactive system that will state: 'During work on a plant equipment modification at Prairie Island Nuclear Plant Unit 1 last week, some gasket material being removed was found to contain asbestos. Prairie Island Unit 1 is in the midst of a refueling outage. 'As soon as site management became aware of the concern for potential asbestos containing material, work on the project was suspended, according to Nuclear Management Co., which operates the plant. The air immediately was monitored and tested according to Minnesota Clean Air requirements. The results were well below regulatory limits. However, results from additional testing on surfaces by a certified lab indicated detectable levels of asbestos on some surfaces in the immediate area. 'Trained asbestos workers are performing a complete clean-up of the affected area. 'NMC and its contractor are taking precautionary actions for any employee with a concern for potential exposure. This includes offering an optional asbestos exposure examination in accordance with federal Occupational Safety and Health Administration (OSHA) guidelines. 'Prairie Island's two reactors near Red Wing, Minn., generate 1,076 megawatts of electricity, enough to power one in five homes and businesses in the Upper Midwest. Xcel Energy owns the plant, which is one of six reactors operated by Nuclear Management Company, headquartered in Hudson, Wis.' Unit 1 is currently defueled. The licensee informed state/local agencies/nearby tribal entity and the NRC Resident Inspector. |
| ENS 42504 | 14 April 2006 16:07:00 | At 1425 on April 14, 2006, a lockout trip of 11 Condensate Pump occurred. The condensate pump trip caused an expected lockout trip of 11 Main Feedwater Pump trip. With the loss of 50% of feedwater pump capacity, the Shift Supervisor directed a manual Unit 1 reactor trip. The manual reactor trip was successful and all systems responded as expected. The reactor protection system actuation is reportable under 10CFR 50.72(b)(2). A reactor trip from full power results in an expected steam generator narrow range level shrink to 0%. This resultant narrow range steam generator level caused an expected Auxiliary Feedwater System Actuation. Both 11 and 12 Auxiliary Feedwater Pumps started as expected. Auxiliary feedwater actuation is reportable under10CFR 50.72(b)(3). Investigation is underway to determine the cause of 11 Condensate Pump lockout. Plant operations are underway per emergency procedure 1ES-0.1, Reactor Trip Recovery, and 1C1.3, Unit 1 Shutdown, to stabilize the plant in Mode 3, Hot Standby. All control rods fully inserted. Steam generators are discharging steam to the condenser steam dump system. The Auxiliary Feedwater Pumps are maintaining Steam Generator level. The electrical grid is stable. The licensee will notify the NRC Resident Inspector. |
| ENS 41062 | 22 September 2004 13:09:00 | The following information was obtained from the licensee via facsimile: At approximately 0900 CDT on September 22, 2004, the Goodhue County sheriff's office inadvertently activated the Goodhue County sirens during the conduct of their weekly silent siren test. As a result of the inadvertent siren actuation, Prairie Island Nuclear Generating Plant communicated with the Goodhue County Administrator and the City of Red Wing Mayor's office, as well as a Prairie Island Indian Community representative. No press release is planned. The NRC senior resident inspector was notified. |