Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 53401 | 14 May 2018 13:17:00 | On May 14, 2018, during evaluation of protection for Technical Specification (TS) equipment from the damaging effects of a tornado generated missile, Calvert Cliffs identified a non-conforming condition in the plant design such that specific TS equipment is considered to not be adequately protected from a tornado generated missile. A tornado could generate a missile that could strike the Unit 1 Saltwater system header and associated piping. This could result in damage to the unit 1 Saltwater system header which could affect the ability of the Unit 1 Saltwater subsystems to perform their design function if such a tornado would occur. This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) for any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety, and per 10 CFR 50.72(b)(3)(v)(D) for any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. This condition is being addressed in accordance with NRC enforcement guidance provided in EGM 15-002 and DSS-ISG-2016-01. Compensatory measures have been implemented in accordance with these documents. The NRC Resident Inspector has been informed of this notification. |
| ENS 51577 | 1 December 2015 20:25:00 | On 12/01/2015 at 1820 EST, the Main Control Room received a 22 Steam Generator Feed Pump trip. The 22 Steam Generator Feed Pump was not able to be reset and the Main Control Room manually tripped the Unit 2 Reactor. The licensee entered Emergency Operating Procedure (EOP)-0, 'Post Trip Immediate Actions' and all safety functions were met. At 1833, Unit 2 transitioned into EOP-1, 'Uncomplicated Reactor Trip.' At 1841, Unit 2 transitioned into Operating Procedure #4 , 'Plant Shutdown from Power to Hot Stand-by.' The plant is stable in Mode 3. All control rods inserted fully on the reactor trip. No primary or secondary safety relief valves lifted. The steam generators are being fed by the 21 steam generator feed pump and decay heat is being dumped to the condenser via the steam dumps. The electric plant is in a normal shutdown electrical lineup and there was no impact on Unit 1. Unit 1 continues to operate at 100 percent power. The cause of the 22 steam generator feed pump trip is still under investigation. The licensee notified the NRC Resident Inspector. |
| ENS 50961 | 7 April 2015 15:45:00 | A loss of Main Generator Load which caused a Reactor Trip on Units 1 & 2. A switchyard voltage transient from a highline occurred, which caused an undervoltage condition on both units' safety related 4KV buses. Unit 1 is on normal heat removal to the condenser. Unit 2 is on auxiliary feedwater and normal condenser bypass valves for temperature control. An Auxiliary Feedwater Actuation System (AFAS) actuation occurred on Unit 2. The (Unit 2) 2B emergency diesel generator did not start and load on its respective 24-4 KV bus. The 24-4KV Bus was repowered from the alternate feeder breaker. Cause of the emergency diesel failure to start is under investigation. All safety functions are met for both units. All control rods fully inserted. The site is in a normal shutdown electrical configuration powered from offsite. The site plans to stay in Mode 3 pending restart. The licensee notified the NRC Resident Inspector, State and local authorities. A press release is planned.
During post trip review, it was determined that the 21 saltwater pump had to be manually started. With the failure of 2B emergency diesel generator, there were no saltwater pumps running for approximately 12 minutes. Additional troubleshooting determined the 2A emergency diesel generator sequencer did not automatically start 21 saltwater pump. The 2B emergency diesel generator was returned to service on 4/8/2015 at 1730 (EDT). The loss of saltwater (pump) and emergency diesel generator is reportable as an event that could have prevented fulfillment of a safety function and is also an unanalyzed condition. The licensee has notified the NRC Resident Inspector. Notified R1DO (Ferdas), IRD MOC (Grant), NRR EO (Morris). |
| ENS 49449 | 18 October 2013 14:05:00 | At 0830 EDT, Calvert Cliffs Nuclear Power Plant determined that the following was an unanalyzed condition: As a result of recent industry operating experience (OE 305419) regarding the impact of unfused direct current (DC) ammeter circuits in the Control Room, Calvert Cliffs performed a review of ammeter circuitry. The review determined the described condition to be applicable to Calvert Cliffs resulting in an unanalyzed condition with respect to 10 CFR 50 Appendix R analysis requirements. The wiring design for the ammeters contains a shunt in the current flow from each DC battery or charger. The ammeter wiring attached to the shunt does not contain fuses. It is postulated that a fire in the Unit 1 Cable Spreading Room could cause one of the ammeter wires to hot short to ground. Concurrently, the fire causes another DC wire from the opposite polarity on the same battery to also short to ground. This would cause a ground loop through the unfused ammeter cable. The potential exists that the cable could heat-up causing a secondary fire in the Unit 2 Cable Spreading Room. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to safely shutdown per 10 CFR 50 Appendix R. This condition is reportable as an eight hour ENS report in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. Compensatory measures (fire watches) have been implemented for affected areas of the plant. The NRC Resident Inspector has been notified. |
| ENS 49424 | 10 October 2013 07:25:00 | At 0538 (EDT on 10/10/13), Calvert Cliffs was notified by Calvert Control Center, that a siren in the Calvert County Area was activated. (It was) determined to be siren C-15 on Lloyd Bowen Road. This is 1 of 73 sirens. Per (procedure) CNG-NL-1.01-1004 this is a verbal report to Calvert Control Center. This event is reportable as a 4 hour non emergency notification 10CFR50.72(b)(2)(xi) as: any event resulting in notification to other government agencies that has or will be made. Heavy rains in the area are believed to have caused the siren activation. Maintenance personal have been dispatched to repair the siren. The licensee has notified the NRC Resident Inspector. |
| ENS 48087 | 11 July 2012 02:23:00 | A 'Communications Network Module' failed rendering the Emergency Response Display System (ERDS) incapable of transmitting data to the NRC. ERDS is out of service for both Unit 1 and Unit 2. Should an emergency be declared during this period, the Control Room will continue to have the capability to retrieve plant data inputs to assess plant conditions and perform core damage assessment. Control Room Emergency Response Organization personnel will use backup methods already captured in emergency response procedures to disseminate plant parameter data to the effected emergency response facilities and NRC during the plant data network outage. The module was removed from service and ERDS was restored at 2325 (EDT). The licensee will notify the NRC Resident Inspector. |
| ENS 47413 | 3 November 2011 23:26:00 | During the conduct of a system vulnerability assessment by Engineering on the emergency diesel system. a discussion was held regarding the impact of a fire on the DG starting air system. Subsequently it was recognized that components of the system were vulnerable to damage during a fire. A review of the Appendix R analysis was conducted and it was determined that this vulnerability was not analyzed in the evaluation. This is reportable to Unit 2, as Unit 1 has a separate diesel building for the 1-Alpha emergency diesel. The NRC Resident Inspector has been notified.
The Appendix R analysis was updated and no changes to the plant or procedures resulted. Therefore, no unanalyzed condition that significantly degraded plant safety existed. This event is being retracted. The NRC Resident Inspector has been notified. R1DO (Joustra) notified. |
| ENS 46516 | 29 December 2010 09:06:00 | This is an eight hour report per 10 CFR 50.72 (b)(3)(xiii). Calvert Cliffs Nuclear Power Plant (CCNPP) will be implementing a scheduled maintenance to the microwave radio system to improve reliability of the system at the Emergency Operations Facility (EOF), State and County facilities. This work will require that the microwave radio system at the EOF be removed for a period of approximately 6 to 8 hours. During this time, the following systems will be impacted for the duration of maintenance: 1. The plant's (e.g., Control Room, Technical Support Center (TSC), Simulator) Dedicated Offsite Agency telephones will be out of service. (EOF's system will continue to function) 2. 800 MHz desk set radios at the EOF only will be out of service. 3. 153.44 MHz frequency at the EOF only will be out of service. (backup for MEMA and MDE) 4. MIDAS Terminal (Meteorological Data) located in the Dose Assessment Office at the EOF will be out of service. 5. TSC Computer data transfer to the EOF only will be out of service. Once the scheduled maintenance starts the systems (listed above) can be returned to service within 1 hour. Should an emergency be declared during this period, the Control Room will continue to have the capability to make the notification to the offsite agencies using the direct line for the appropriate agencies. The Emergency Preparedness communications procedure provides a chart listing the communication devices available and the order in which the process is to be implemented. MIDAS (Meteorological Data) will continue to be operational at the site and can be obtained by contacting the Control Room or TSC. The ERPIPs also provide a backup process and the instructions necessary for the EOF Dose Assessment Office to obtain Meteorological Data. Plant data can be obtain from the CR or TSC and will continue to be downloaded from the plant computer to the ERO SharePoint site. All work associated with this microwave radio maintenance will be performed in an expeditious manner consistent with the goal of minimizing unavailability of the systems listed above. A test of all systems will be performed at the completion of the maintenance. All EOF responders and Control Room personnel have been briefed on this work and expected contingent actions. This job will start on Wednesday, December 29, 2010 at approximately 8:00 am. We anticipate that all work will be completed by 4:00 pm on the same day, including testing of the system. We will provide a notification update upon completion of the job. The licensee informed the NRC Resident Inspector. Licensee will also notify state and local governments.
Communications are back in full service as of 1220 on 12/29/10. Notified R1DO(Hansell) |