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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 51931 | 15 May 2016 16:18:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Excessive Unidentified Leakage During Plant Startup | Unit 2 experienced RCS Leakage, potentially pressure boundary leakage, or Unidentified Leakage greater than 10 gpm for (greater than) 15 minutes. Reactor Vessel Flange Temperature High Leakoff alarm was received. This met threshold for declaration of an Unusual Event at 1118 CDT per MU6. Unit 2 is currently in MODE 3. Investigation is in progress to identify specific leakage location. The plant is stable, leakage indicates about 32 gpm and the startup has been stopped. There is no impact on Unit 1. The licensee notified the NRC Resident Inspector and State authorities. Notified DHS SWO, FEMA Ops Center, DHS NICC,. Notified FEMA National Watch and Nuclear SSA via email.
At 1459 CDT, the conditions under MU6 are no longer met. The site has terminated the Unusual Event. In addition, a press release will be made of this event. Unit 2 is stable and in Mode 3 pending further evaluation. The leak stopped when a loop drain isolation valve was closed. The licensee notified the NRC Resident Inspector and State and local authorities. Notified the R3DO (Duncan), NRR EO (Morris), IRD MOC (Grant), DHS SWO, FEMA Ops Center, and DHS NICC. Notified the FEMA National Watch and Nuclear SSA via email. | ||
| ENS 51633 | 3 January 2016 05:40:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Inadvertant Siren Actuation | On 01/02/2016 at 2340 (CST), personnel at the Ogle County 9-1-1 call center inadvertently actuated the emergency response sirens associated with Byron Generating Station multiple times. The emergency response sirens were secured at approximately 2350. This event is being reported under 10CFR50.72(b)(2)(xi) for, 'any event or situation, related to the health and safety of the public or on site personnel, or protection of the environment, for which a news release is planned or notification to other government agencies has been or will be made.' The licensee has notified the State of Illinois and the NRC Resident Inspector. All sirens are operable and available if needed. | ||
| ENS 49137 | 20 June 2013 11:00:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Sulfuric Acid Spill Requiring Offsite Notification | In the owner controlled area, the plant has a tank of sulfuric acid (93% concentration, UN # 1830) for chemical control of the Circulating Water system used in the non-safety related electrical power production portion of the plant. At 0600 (CDT), a routine inspection of the tank found acid within the berm surrounding the tank. A leak was discovered in the berm and sulfuric acid leaked onto the surrounding area and nearby drainage ditch. The quantity of leaked acid has been estimated to be 120 gallons. The source of the leak has been determined to be a pipe on the tank and it has been isolated with a closed valve. The tank level has been stable for 4 hours. The leaked acid is contained within approximately 70 linear feet of the (limestone) ditch and has not left the site. On-site operations and chemistry personnel are neutralizing the acid with soda ash and a tanker truck was contracted to arrive on site this morning to empty the acid tank contents until a repair can be accomplished. The leak was discovered at 0600 and isolated about 0630 CDT. The licensee notified the NRC Resident Inspector. | Circulating Water System | |
| ENS 48278 | 5 September 2012 17:25:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification of Sodium Hypochlorite Spill | At 1225 on 9/5/12, the Main Control Room received a report of a Sodium Hypochlorite spill estimated at 100 gallons at the Byron Circulating Water Pump House. The spill was caused by a leak from the hose of the Chemical Delivery truck. A spill of greater than 80 gallons of Sodium Hypochlorite is considered a reportable quantity. The spill was reported to the Illinois Emergency Management Agency (IEMA) in accordance with 29 IAC 430.30 and 35 IAC 750.304, and the National Response Center in accordance with 40 CFR 302.6. Notification to IEMA was performed at 1235 on 9/5/12, and notification to the National Response Center was performed at 1245 on 9/5/12. The notifications to other government agencies is reportable to the NRC in accordance with 10 CFR 50.72(b)(2)(xi). The licensee has notified the NRC Resident Inspector. | ||
| ENS 47708 | 28 February 2012 23:31:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unusual Event Due to Loss of Offsite Power | Byron Unit 1 declared an Unusual Event due to a loss of offsite power for greater than 15 minutes (EAL MU-1). The 1A and 1B emergency diesel generators auto-started and automatically restored power to ESF (Engineered Safety Feature) Busses 141 and 142. The 1A Auxiliary Feedwater pump auto-started due to an undervoltage signal to ESF bus 141. The 6.9 KV Busses (Non-ESF) and 4.16 KV Busses (Non-ESF) auto transferred to the Unit Auxiliary Transformers and Unit 1 remained online. The ESF reserve feed breakers are available and in the process of transferring ESF loads over to Unit 2 via the ESF cross-ties. This will allow shutdown of the 1A and 1B diesel-generators and allow alignment to standby status. Switchyard repairs are being initiated. The licensee notified the State of Illinois, Ogle County, Oregon and Byron municipalities and the NRC Resident Inspector. The licensee plans on issuing a news release. Unit 2 remained online and was unaffected throughout the event. Notified Nuclear SSA and NICC vie email.
Termination of Unusual Event. Repairs to switchyard components are complete. Offsite power has been restored to Unit One System Auxiliary Transformers. Unit One 4 KV ESF busses have been re-energized from Unit One System Auxiliary Transformers and are no longer cross tied to Unit Two System Auxiliary Transformers. This restores the normal electrical lineup to the ESF busses. The entry conditions for MU-1 are no longer met. The licensee has notified the NRC Resident Inspector, the State of Illinois, Ogle County, Oregon and Byron municipalities. Notified R3DO (Stone), NRR EO (Lee), IRD (Morris), and other FEDS (DHS SWO, DHS NICC, FEMA, and NuclearSSA via email). | Emergency Diesel Generator Auxiliary Feedwater | |
| ENS 47624 | 30 January 2012 16:01:00 | 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 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Unusual Event Due to Loss of Offsite Power Greater than 15 Minutes | At 1101 EST, Byron Unit-2 experienced a reactor trip due to RCP undervoltage. All rods fully inserted, MSIV's were manually closed and decay heat is being removed by Auxiliary Feedwater pumps running and steam leaving via atmospheric relief valves. The unit is currently in a natural circulation cooldown with the diesels supplying station emergency loads. Licensee will be cooling the plant down to Mode 5. At 1118 EST, Byron declared an Unusual Event due to a loss of offsite power on Unit 2 from a faulted Station Auxiliary Transformer (SAT). The faulted SAT caused both 6.9 kV and 4.1 kV bus voltage to drop. Smoke was observed coming from the SAT with no visible flames being apparent. This caused bus loads to trip without a complete loss of ESF busses 241 and 242. These buses were manually disconnected from the SAT, which transferred the load to the emergency diesel generators 2A and 2B. Both diesel generators started and loaded without incident. Offsite assistance was requested from the local fire department as a precaution. The licensee is also declaring notification for 10 CFR 50.72(b)(3)(v)(D) Unit 1 is not being affected by this event and remains at 100% power. The licensee has notified the NRC Resident Inspector.
At 2000 CST on 1/31/12, Byron terminated their Unusual Event due to the Loss of Offsite Power to Unit 2. Switchyard repairs were completed and offsite power has been restored to essential busses 241 and 242 thru System Auxiliary Transformers 242-1 and 242-2. Unit 2 Emergency Diesel Generators have been shutdown. The licensee is citing classification 10 CFR 50.72(c)(1)(iii) The licensee has notified the NRC Resident Inspector. Notified R3DO (James Cameron), NRR EO (Louise Lund), IRD MOC (Scott Morris), DHS (Konopka) and FEMA (Hollis). Licensee may issue a press release. | Emergency Diesel Generator Auxiliary Feedwater | |
| ENS 44443 | 28 August 2008 11:15:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Small Oil Spill Into Intake Bay | During a diver inspection of 0A SX (Essential Service Water) Makeup pump intake structure, hydraulic oil was spilled into the intake bay. The oil was Envirologic 146, a natural ester based hydraulic oil. It is believed a total of approximately 2 gallons of oil leaked from the pump into the intake bay. Approximately 6 inch - 12 inch oil sheen was seen on the Rock River. Oil booms used to capture spilled oil. Oil spill was contained at 0710 CDT. Licensee notified the National Response Center, Illinois Emergency Management Agency, and Ogle county Emergency Services Disaster Agency. The licensee notified the NRC Resident Inspector. National Response Center Report #: 882049 | ||
| ENS 44094 | 25 March 2008 23:49:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Loss of Offsite Power Due to Station Auxiliary Transformer Fault | At 1835 on March 25, 2008, Unit 2 experienced a Loss of Offsite Power. At 1849, an Unusual Event was declared. Station Auxiliary Transformer (SAT) 242-2, Phase C, experienced a Phase Overcurrent. This resulted in an isolation of the SAT, a loss of offsite power, and an automatic Fire Protection deluge of the SAT. No fire was confirmed. All equipment responded as required. The appropriate abnormal operating procedure was entered for event mitigation and is in progress. The Unit 2 Emergency Diesel Generators are supplying required safety-related power. Unit 2 remains at power. The plant is stable and all equipment is functioning as required. The licensee is assessing a cross-tie to Unit 1 which is unaffected by this event and in the refueling mode. The licensee notified the State and local authorities and the NRC Resident Inspector. Notified DHS (Greg Ray), FEMA (Erwin Casto), DOE (Sal Morrone), USDA (Timmons), HHS (Rick Turner), EPA/NRC (Petty Officer Thompson Report #866038).
The emergency buses on Unit 2 have been re-energized by offsite power supply sources via Unit 1 SAT. The Unit 2 EDGs have been secured and placed back in standby. The licensee is developing a recovery plan to restore a Unit 2 SAT to supply offsite power to Unit 2 loads. This will require such things as analyzing chemistry samples of the affected SAT transformers and assessing the protective relaying. In addition, some switchyard realignment will be necessary. The licensee is currently in a 72 hour LCO under Tech Spec 3.8.1 for the current electrical alignment. The NRC Resident Inspector is onsite and the NRC Region continues to monitor the situation.
At 2309 (hrs. CDT) on 3/27/08, Byron Unit 2 terminated an Unusual Event that was declared at 18:49 on 3/25/08, in accordance with EAL M.U.1 due to a loss of offsite power to transformers 242-1 and 242-2. Transformer 242-1has been energized from offsite power and is supplying Unit 2 ESF busses 241 and 242. The entry conditions for M.U.1 are no longer met. A press release will be issued. Transformer 242-2 is out of service and isolated for repairs. The licensee notified the NRC Resident Inspector. Notified R3DO (Hills), NRR EO (Ross-Lee), IRD (McDermott), DHS SWO (Doyle), FEMA (Liggett), DOE (Morrone), EPA (Allison), USDA (Timmon) and HHS (Dalziel). | Emergency Diesel Generator | |
| ENS 43807 | 27 November 2007 15:15:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Alert Declared Due to Oxygen Deficient Atmosphere | An ALERT was declared at 0915 CST. A nitrogen freeze seal was being used on a 3 inch pipe in the 1B RHR and 1B Containment Spray pump room. A leak developed on the freeze seal jacket. This created an oxygen deficient atmosphere (less than 19.5 percent oxygen). The nitrogen supply was isolated. And the room was evacuated. The alert was declared in accordance with Emergency Action Level (EAL) "hazard alert #7 (HA7)." Additional ventilation was being placed in the area to restore normal oxygen levels. EAL table entry HA7 is for "Release of toxic or flammable gases within or restricting access to a vital area which jeopardizes operation of systems required to maintain safe operations or establish or maintain safe shutdown. No personnel injuries occurred. Oxygen levels were returned to acceptable levels at 0933 CST. The licensee notified the NRC Resident Inspector.
The ALERT was terminated at 1103 CST. Notified IRD (McDermott), R3DO (Lipa), DHS SWO (Mary Anne), FEMA (Dan Sullivan), DOE (Anthony Parsons), EPA (Ms Ross), USDA (Andrew Watts), and USDA (Rick Turner). | Containment Spray | |
| ENS 42374 | 24 February 2006 14:54:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Due to Fire in the Protected Area Not Extinguished within 15 Minutes | At 0836 the control room received a Unit 1B CV/SI pump room fire alarm. An operator reported smoke in the 1B SI pump room at 0840. An unusual event was declared at 0854 due to HU6, fire in the protected area not extinguished within 15 minutes. Sounds of arcing can be heard but flames have not been located. It is suspected that an RWST heater has failed in a pipe tunnel above the 1B SI pump room. The breaker for the RWST heater has been deenergized. The RWST heater pump has been deenergized. Offsite fire department assistance has been requested. The licensee is ventilating the area in order to perform a more thorough inspection of the area and determine the cause of the fire. Both Units1 and 2 remain at 100% reactor power. The NRC Resident Inspector, State and local officials have been notified by the licensee. The NRC has entered the Monitoring Mode at 1036. The NRC Operations Center notified the following organizations: HHS/FDA (V. Howard-King), USDA (Brown), EPA/NRC (Rawls) and DOE (Silva).
At 11:09 CST on 02/24/06, Byron terminated an Unusual Event that was declared at 08:54 CST today in accordance with HU6 due to a fire in the Protected Area not extinguished within 15 minutes. The RWST (Refueling Water Storage Tank) heater has been confirmed as the source of the smoke that caused the fire alarm. The heater has been deenergized and the area is being ventilated. The NRC exited the Monitoring Response Mode at 12:52 EST. The NRC Resident Inspector and State officials have been notified by the licensee. NRC made notifications to R3DO(Hills), IRD Managers (Leach, Blount, Wilson), NRR EO (Jung), NRR ET (Dyer), HQ PAO (Brenner), R4DO(Pick), DHS (Carledge), FEMA (Liggett), HHS/FDA( Miller), USDA (Byzustek), EPA/NRC (Rawls, Ribordy), and DOE (Silva). | ||
| ENS 42212 | 20 December 2005 23:12:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification - Press Release | This notification is being made in accordance with 10CFR50.72(b)(2)(xi) due to a press release being issued. On 12/19/05 at 14:46 CST, a licensee employee was leaving the station and received a gunshot wound to the left leg/ankle while walking between the Byron Main Access Facility and the Byron Pre Access Facility. Onsite personnel provided first aid assistance, and an offsite ambulance responded to the scene. The injured individual was transported to St. Anthony's Hospital in Rockford, Illinois. The injured individual is in stable condition and is expected to make a full recovery. The Ogle County Sheriff's Office is conducting an investigation into the event. Byron Security Firing Range activities were in progress at the time of the event and were suspended immediately upon notification of the injury. A press release is being issued due to media attention related to this event. The NRC Resident Inspector has been notified, as well as NRC personnel from Region III and NRC Headquarters. |