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 Entered dateSiteRegionReactor typeEvent description
ENS 5432511 October 2019 14:22:00Calvert CliffsNRC Region 1At 1300 EDT, a Technical Specification required shutdown was initiated at Calvert Cliffs Unit 1. Technical Specification Action 3.1.4.C (Restore Control Element Assembly (CEA) alignment) was entered on 10/11/2019 at 1100 EDT, with a Required Action to reduce thermal power to less than 70 percent Rated Thermal Power and restore CEA alignment within 2 hours. This Required Action was not completed within the Completion Time; therefore, a Technical Specification required shutdown was initiated, and this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(i). At 1345 EDT, CEA alignment was restored and Technical Specification 3.1.4 (Control Element Assembly Alignment) was met. Reactor Power is being stabilized. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."
ENS 539219 March 2019 13:59:00Calvert CliffsNRC Region 1A sewage line on the south end of the plant backed up causing sanitary wastewater to flow into storm drains and out to the Chesapeake Bay. This is a required notification of the Maryland Department of the Environment under COMAR (Code of Maryland Regulations) 26.08 for discharge of a pollutant into navigable waters or the adjoining shoreline. The amount has been estimated at less than 1000 gallons and the source has been isolated and storm drains have been covered to stop any flow into them and subsequently to the Chesapeake Bay. This notification is made in accordance with 10CFR50.72(b)(2)(xi) due to notification of a state agency. The licensee notified the NRC Resident Inspector.
ENS 5366312 October 2018 03:58:00Calvert CliffsNRC Region 1During a post maintenance start of the 1B diesel generator, the air start solenoid valves did not close as expected. This resulted in lowering air pressure in the common air start headers causing inoperability of the 2A and 2B diesel generators at time 23:03. The 1B diesel generator was isolated from the common air start header, which restored the air start header pressure to the 2A and 2B diesel generators. The 2A and 2B diesel generators were declared operable at 23:34. The NRC Resident Inspector was notified.
ENS 534937 July 2018 08:29:00Calvert CliffsNRC Region 1At 0242 EDT, the CCNPP (dual unit, single control room) control room supply damper failed shut. This rendered the Unit 1 and Unit 2 control room ventilation inoperable and the appropriate LCOs were entered. At 0249, control room ventilation was restored to service and the appropriate LCOs were exited. This is being reported under 10 CFR 50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector.
ENS 5340114 May 2018 13:17:00Calvert CliffsNRC Region 1CEOn 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 5264025 March 2017 09:28:00Calvert CliffsNRC Region 1CE

While performing a purification subsystem alignment on the Unit-2 Refueling Water Tank, an inadvertent transfer of Refueling Water Tank level to the common Spent Fuel Pool occurred. This transfer resulted in lowering Unit-2 Refueling Water Tank level below the Technical Specification (TS) required limit for the current mode of operation at 0142 (EDT) on 3/25/17. Upon recognition of the inadvertent transfer, Operations secured the lineup and restored Unit-2 Refueling Water Tank level to its normal operating band at 0225 on 3/25/17. This event is reportable under 10 CFR 50.72(b)(3)(v)(D) '...any event or condition that at the time of discovery could have prevented the fulfillment of the safety function structures or systems that are needed to mitigate the consequences of an accident.' With less than the required Technical Specification volume in the Refueling Water Tank, insufficient volume existed in the Refueling Water Tank to maintain 30 minutes of full flow Safety Injection, and subsequent continued pump operation after transition to recirculation mode of operation. This level is required by Technical Specification 3.5.4.B and has a one hour action statement to restore level. The NRC Resident Inspector has been notified.

  • * * RETRACTION FROM KENT MILLS TO DONALD NORWOOD AT 1637 EDT ON 3/30/2017 * * *

The purpose of this notification is to retract ENS notification 52640 made on March 25, 2017 for Calvert Cliffs. After further evaluation, it has been determined that the volume of water in the Unit 2 Refueling Water Tank was never below the TS required volume of 400,000 gallons. The evaluation considered the as-found condition of the level transmitter and the existing environmental conditions of the tank in determining the actual RWT water volume on the day of the event. Therefore, this event does not meet the criteria of 10 CFR 50.72(b)(3)(v)(D) and the ENS report is being retracted. The licensee will notify the NRC Resident Inspector. Notified R1DO (Cook).

ENS 524095 December 2016 16:24:00Calvert CliffsNRC Region 1CEA non-licensed supervisory employee had a confirmed positive for a prohibited substance during a random fitness-for-duty test. The individual's unescorted access to the plant has been denied. The licensee has notified the NRC Resident Inspector.
ENS 524064 December 2016 01:48:00Calvert CliffsNRC Region 1CEOn 12/3/16 at 2224 EST, Calvert Cliffs Unit-2 experienced an automatic reactor trip from full power due to a leak in the Unit-2 Main Turbine Electro-Hydraulic Control (EHC) system. The EHC leak caused the Unit-2 Main Turbine governor valves to close, resulting in a turbine trip and automatic reactor trip. The site Outage Control Center is manned, and investigation into the cause of the leak is underway. Unit-2 remains stable in Mode 3 with normal heat removal. Unit-1 remains at full power and was not affected by the trip. The plant is in a normal shutdown electrical lineup. All Control rods fully inserted and no primary or secondary safety relief valves lifted during the trip. The licensee has notified the NRC Resident Inspector. The licensee will be notifying Calvert County.
ENS 5196731 May 2016 18:12:00Calvert CliffsNRC Region 1CEOn 05/31/2016 at 1626 (EDT), a Reactor Trip occurred on Loss of Load RPS (Reactor Protection System) actuation. The Turbine Trip was apparently caused by a failed ESFAS (Engineered Safety Feature Actuation System) logic module. The failed NSR (Non Safety Related) logic module was associated with 11 Steam Generator High Level Turbine Trip. All systems responded as designed. Normal decay heat removal is to the condenser. All offsite power sources remained in service. The NRC Resident Inspector was notified.
ENS 5174720 February 2016 09:12:00Calvert CliffsNRC Region 1CEDuring the CCNPP (Calvert Cliff Nuclear Power Plant) Unit 1 Refueling, (an ultrasonic test) examination of the Unit 1 dissimilar metal weld (DMW) of the pressurizer safety relief valve RV-201 safe end weld found an indication that is approximately 80 percent though-wall, inside diameter connected axial flaw in weld #4-SR-1006-1. This is an ASME Class 1 component and Unit 1 has entered the requirements of Technical Requirements Manual (TRM) 15.4.3.A. CCNPP Event #4254. The licensee has notified the NRC Resident Inspector.
ENS 5168325 January 2016 05:45:00Calvert CliffsNRC Region 1CEAt 0315 EST on 1/25/16, Calvert Cliffs Unit 1 was manually tripped from 10 percent power due to elevated condenser sodium levels. All systems responded per design. Main Feed was secured and auxiliary feed water was initiated. The elevated sodium levels are believed to be due to a condenser tube leak. The reactor is currently shutdown and stable in Mode 3 and will remain in Mode 3 until repairs are effected. Unit 2 was not affected and remains at full power. The Licensee has notified the NRC Resident Inspector.
ENS 515771 December 2015 20:25:00Calvert CliffsNRC Region 1CEOn 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 515102 November 2015 09:20:00Calvert CliffsNRC Region 1CE

A planned modification at Calvert Cliffs Nuclear Power Plant will remove the Spent Fuel Pool Area Radiation Monitoring system from service. The planned out of service window is expected to be 7 weeks, beginning 11/02/15 and ending 12/18/2015. During this time portable radiation monitors will be installed as compensatory measures to monitor and support timely and accurate EAL declarations. Affected Emergency Response Organization personnel have been made aware of the compensatory measures. This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii) due to a planned event that affects Emergency Preparedness Assessment Capability for greater than 72 hours. An update will be provided once the Spent Fuel Pool Area Radiation Monitoring system is restored to normal operation. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE AT 1616 EST ON 12/18/2015 FROM BRIAN HAYDEN TO MARK ABRAMOVITZ * * *

This is concerning the planned modification to Calvert Cliffs Nuclear Power Plant Spent Fuel Area Radiation Monitoring System. The modification window is extended to January 8, 2016. Compensatory measures that were put in place on November 2, 2015 will continue to be in effect until the completion of the modification testing and the new equipment is fully in service. The licensee notified the NRC Resident Inspector. Notified R1DO (Ferdas).

  • * * UPDATE FROM TIM HUBER TO JEFF ROTTON AT 1547 EST ON 01/08/2016 * * *

This is concerning the planned modification to Calvert Cliffs Nuclear Power Plant Spent Fuel Area Radiation Monitoring System. The modification window was originally extended to January 8, 2016 as updated on December 18, 2015. Based on field equipment issues during the installation process, the modification window has been extended to February 12, 2016. Compensatory measures that were put in place on November 2, 2015 will continue to be in effect until the completion of the modification testing and the new equipment is fully in service. The licensee notified the NRC Resident Inspector. Notified R1DO (Dimitriadis).

ENS 509617 April 2015 15:45:00Calvert CliffsNRC Region 1CE

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.

  • * * UPDATE FROM JAY GAINES TO DANIEL MILLS AT 0129 EDT ON 4/9/2015 * * *

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 5075222 January 2015 18:51:00Calvert CliffsNRC Region 1CE

On 1/20/15, it was determined that a certain line up of component cooling heat exchangers and shutdown cooling heat exchangers could exceed the design basis temperatures for the component cooling water system following a design basis accident. Although not a safety concern at this time because of low ultimate heat sink temperatures (which cools component cooling water), in the past the ultimate heat sink temperatures have been high enough to create this condition. This particular heat exchanger line up was unanalyzed in that the ultimate heat sink temperature limits were not known until 1/22/15. This issue has been entered into the corrective action program. A review of Control Room logs for 2014 showed that in 1 instance for Unit 1 and 1 instance for Unit 2, the Units were in an unanalyzed lineup with ultimate heat sink temperature greater than the maximum now calculated. During these instances, both Units had an unanalyzed condition that had potential to significantly degrade plant safety and is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified.

  • * * RETRACTED ON 03/03/15 AT 1410 EST FROM CHARLES MORGAN TO JEFF HERRERA * * *

Further engineering analysis has refined the ultimate heat sink temperature that provides an acceptable safety system response with the component cooling water and shutdown cooling heat exchanger lineups in question. The revised information demonstrates that the system lineups that occurred in the last 12 months did not result in an unanalyzed condition that significantly degrades plant safety. This event notification is retracted. The NRC Resident Inspector will be notified. The R1DO (Burritt) was notified.

  • * * UPDATE ON 03/12/15 AT 1303 EDT FROM ED SCHINNER TO DANIEL MILLS * * *

The retraction statement provided on 3/3/15 incorrectly addressed system lineups limited to the last 12 months. The original withdrawal was prematurely submitted and therefore the original notification (Event report 50752) is not retracted and remains valid. The NRC Resident Inspector has been notified. The R1DO (Cook) was notified.

ENS 5068717 December 2014 12:10:00Calvert CliffsNRC Region 1CEAt 0417 EST on December 17, 2014, the Shift Manager was notified by Radiation Protection (RP) personnel that the Unit 2 AMP-200 radiation monitor used for backup monitoring of the Unit 2 Main Plant Vent when the Unit 2 Wide Range Noble Gas Monitor (WRNGM) is (Out of Service) OOS had experienced a malfunction that caused it to spike high for approximately five minutes before returning to a baseline value of 0 mR/hr. At the same time, the Unit 2 WRNGM was already out of service for the completion of a planned surveillance test. The Unit 2 WRNGM had been removed from service at 0740 EST on December 16, 2014. While the WRNGM is OOS, the AMP-200 radiation monitor is procedurally relied upon for being used as the means for determining Alert, Site Area Emergency, and General Emergency entry criteria under the applicable Emergency Action Level (EAL) Initial Conditions (ICs). The Unit 2 Main Vent Gaseous Monitor is procedurally relied upon for being used as the means for determining Unusual Event entry criteria for the same EAL ICs and remained in service during this time. After investigation by site RP and Maintenance personnel, the functionality of the Unit 2 AMP-200 was restored at 0700 EST on December 17, 2014 following a successful source check of the instrument. The investigation identified that the AMP-200 cable contacts were found wet and were subsequently cleaned and dried. Actions have been taken to prevent reoccurrence of the wetting condition. During the time from 0417 to 0700 EST on December 17, 2014, Unit 2 had a condition that represented a loss of emergency assessment capability and is a reportable condition in accordance with 10 CFR 50.72(b)(3)(xiii). The NRC Resident Inspector has been notified and the NRC the notification time with the NRC Headquarters was 1210 EST.
ENS 505021 October 2014 15:07:00Calvert CliffsNRC Region 1CE

At 0750 EDT on October 1, 2014, the Shift Manager was notified that site Information Technology (IT) personnel were being mobilized to investigate a potential voice and network loss at the Emergency Operations Facility (EOF) and Joint Information Center (JIC). Site IT personnel were notified by offsite IT resources at 0727 EDT on October 1, 2014 of the issue that was first identified by IT monitoring software at 0124 on October 1, 2014. The site IT personnel that responded to the EOF and JIC reported to site Control Room and Emergency Preparedness (EP) personnel at 0845 that connectivity to the Exelon network and the internet was unavailable at both the EOF and the JIC. This loss of connectivity would prevent the ability of the EOF Emergency Response Organization (ERO) personnel to directly monitor key plant parameters via the site's Plant Process Computer (including the Site Parameter Display System) and other network-based plant parameter display systems. Site IT and EP personnel determined that the following communications equipment was not impacted by the connectivity issue: - Dedicated Offsite Agency Phones (primary method for contacting state and local agencies) - Commercial Phones and dedicated bridge line (primary method for contacting other site Emergency Response Facilities) - FTS-2001 Phones (e.g., ENS and HPN lines) - ERDS Additionally, EP personnel verified with Dose Assessment Office personnel that dose assessment and dose monitoring functions from the EOF could still be performed without delay. Site IT personnel reported to the Control Room at 1135 that connectivity to the Exelon network and the internet had been restored to a fully functional status. While site and fleet IT personnel continue to address and verify all appropriate corrective actions have been taken to prevent recurrence of the connectivity issue, the site has employed appropriate compensatory measures to ensure that the verbal transmission of key plant parameters from the site (Technical Support Center or Control Room) to the EOF is recognized and maintained. The NRC Resident Inspector has been notified.

  • * * RETRACTION FROM TIM HUBER TO JEFF ROTTON AT 1208 EDT ON 10/27/2014 * * *

This update retracts Event Report #50502, which reported that a loss of connectivity to the Exelon network and internet at the Emergency Operations Facility (EOF) and Joint Information Center (JIC) had impacted the ability of staff in these facilities to directly monitor key plant parameters via the site's Plant Process Computer and other network-based plant parameter display systems. Subsequent to the identification of this event, further investigation by site and fleet staff determined that adequate direction was included in applicable Emergency Response Organization (ERO) procedures to respond to data display system failures of this type. Specifically, the checklist (procedure) for the Operations Communicator in the EOF provided adequate direction for this ERO member to obtain required plant data from the Operations Communicator located in the Control Room via alternate methods (e.g., over the phone - phone lines remained functional throughout the time that the loss of computer connectivity condition existed). Therefore, this event did not result in a major loss of emergency assessment capability and was not reportable to the NRC under 10CFR50.72(b)(3)(xiii). The NRC Resident Inspector has been notified. Notified R1DO (Bickett) and Cyber Assessment Team via email.

ENS 5030724 July 2014 23:41:00Calvert CliffsNRC Region 1CE

At 2315 EDT on July 24th, 2014, CCNPP (Calvert Cliffs Nuclear Power Plant) U1 identified RCS (Reactor Coolant System) pressure boundary leakage from the instrument line to 1-PDT-123A, 11A reactor coolant pump differential pressure transmitter. Technical Specification 3.4.13, Action B was entered and requires that the unit be placed in Mode 3 within 6 hours and Mode 5 within 36 hours. (CCNPP has) initiated plant shutdown in accordance with this Technical Specification. Therefore, this is reportable under 10 CFR 50.72(b)(2)(i) Plant Shutdown Required by Technical Specifications. This is also reportable under 50.72(B)(3)(ii)(A) as a material defect in the primary coolant system that cannot be found acceptable under ASME Section XI, IWB-3600 or ASME Section XI, Table IWB-3410-1. The licensee notified the NRC Resident Inspector.

  • * * UPDATE FROM JAY GAINES TO VINCE KLCO AT 0320 EDT ON 7/25/14 * * *

The licensee reduced reactor power to 10 percent and entered containment. The pressure boundary leak was isolated and the licensee exited the Technical Specification 3.4.13, Action B. The Technical Specification required shutdown was terminated. The licensee is making preparation to increase power to full load. The licensee will notify the NRC Resident Inspector. Notified the R1DO (Gray).

ENS 500781 May 2014 11:50:00Calvert CliffsNRC Region 1CEAt 1016 (EDT) CCNPP (Calvert Cliffs Nuclear Power Plant) Unit 1 automatically tripped due to an RPS actuation. Cause is under investigation. All safety functions are met with normal heat removal. Electric plant is in a normal lineup. No ESFAS (Engineered Safety Feature Actuation System) actuations have occurred. Steam Generator atmospheric dump valves momentarily opened and then closed. There is no known steam generator tube leakage. All control rods fully inserted on the trip. There was no impact on Unit 2 from this event. The licensee notified the NRC Resident Inspector and provided a courtesy notification to the Calvert County Control Center.
ENS 4988910 March 2014 22:43:00Calvert CliffsNRC Region 1CEAn extent of condition review identified that there were unfused 250 VDC circuits for the battery charger ammeters and the control circuits for various DC lube oil pumps which left the turbine building and went through the respective cable spreading room and up into the Control Room. These circuits are protected by 200 amp fuses and in some cases 100 amp fuses. The concern is that under the fire safe shutdown rules, it is postulated that a fire in one fire area can damage these circuits and cause short circuits without protection that would overheat the cables and possibly result in secondary fires in other fire areas where the cables are routed. The secondary fires could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10 CFR 50 Appendix R. This condition is reportable as an 8-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 licensee has notified the NRC Resident Inspector.
ENS 4975422 January 2014 00:33:00Calvert CliffsNRC Region 1CEDual Unit Trip due to loss of '21' 13 KV bus . All safety functions are met for both units. Unit 1 remained with normal heat removal. Unit 2 lost power to its normal heat sink and is stable on Auxiliary Feed water and Atmospheric Dump Valves for temperature control. Both trips were automatic trips. Due to loss of power a Under Voltage actuation occurred on both units ('14' and '24' 4Kv bus). Due to loss of main feed on Unit 2 a Auxiliary Feed water Actuation System (AFW) actuation occurred on Unit 2. Cause is under investigation. All control rods fully inserted on the loss of power to the Control Rod Drive Mechanisms (CRDMs). Both Units Reactor Coolant Pumps (RCPs) remained running during the transient. The normal Unit 2 heat sink was unavailable due to the loss of the operating circulating water pumps resulting in a loss of condenser vacuum. The Unit 2 AFW actuation included one of two steam-driven pumps and the motor-driven pump. Both Units Emergency Diesel Generators started and loaded and have since been secured. Both Units are stable and will remain in mode 3 (Hot Standby) pending the results of the investigation. The licensee will inform the NRC Resident Inspector.
ENS 4946322 October 2013 16:59:00Calvert CliffsNRC Region 1CEA non-licensed contract employee supervisor had a confirmed positive for alcohol during a random fitness for duty test. The contractor's access to the plant has been terminated. The licensee notified the NRC Resident Inspector.
ENS 4944918 October 2013 14:05:00Calvert CliffsNRC Region 1CEAt 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 4942410 October 2013 07:25:00Calvert CliffsNRC Region 1CEAt 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 493235 September 2013 14:51:00Calvert CliffsNRC Region 1CECCNPP (Calvert Cliffs Nuclear Power Plant) U2 CEA (Control Element Assembly) #27 fully inserted (CEA dropped) into the core during testing per STP 0-029-2. Technical Specification 3.1.4, Action B was entered and required the CEA to be realigned within 2 hours. With this action not met Technical Specification 3.1.4, Action C required the Unit be reduced to < 70% rated thermal power (achieved at 1308 (EDT)) and the CEA to be realigned within 2 hours. With the CEA being unable to be realigned, Technical Specification 3.1.4.F was entered at 1314 (EDT) which requires the Unit to be placed in Mode 3 within 6 hours. A plant shutdown has been initiated in accordance with this Technical Specification. Therefore, this is reportable under 10 CFR 50.72(b)(2)(i), 'Plant Shutdown Required by Technical Specifications.' The licensee will notify the NRC Resident Inspector.
ENS 4926210 August 2013 10:38:00Calvert CliffsNRC Region 1CECalvert Cliffs was notified at 0711 (EDT) by Calvert Control Center that a siren in the Calvert County Area was activated. (It was) determined to be Siren C15 on Lloyd Bowen Road. Per 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 (under) 10CFR50.72(b)(2)(xi) as 'Any event resulting in notification to other government agencies that has or will be made.' The licensee informed the NRC Resident Inspector.
ENS 4905421 May 2013 06:20:00Calvert CliffsNRC Region 1CEReactor trip. All safety functions met with normal heat removal. 22 SGFP (Steam Generator Feedpump) exhibited high vibrations and signs of coupling damage. Further investigation will be performed. All control rods fully inserted on the trip. Steam Generator level is being maintained with the remaining feedpump. Decay heat is being dumped to the main condenser. Electrical power is in the normal shutdown lineup. No relief or safety valves lifted during the trip. There was no effect on Unit 1. The licensee notified the NRC Resident Inspector.
ENS 490129 May 2013 00:09:00Calvert CliffsNRC Region 1CEThe reactor automatically tripped at 2147 EDT. All control rods fully inserted on the trip and all systems responded as expected. Decay heat removal is to the main condenser. The plant is in its normal shutdown electrical lineup. The licensee is investigating the cause of the reactor trip. The licensee notified the NRC Resident Inspector.
ENS 4879027 February 2013 16:08:00Calvert CliffsNRC Region 1CECalvert Cliffs Nuclear Power Plant will perform planned maintenance on the Unit 2 Plant Process Computer (PPC) and associated network infrastructure starting on February 27, 2013. The maintenance will remove the Unit 2 PPC for a planned duration of 5 days and will render the Unit 2 ERDS out of service for this timeframe. The current outage schedule has power being restored on 03/04/2013. 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 at all times. Control Room Emergency Response personnel will use emergency response procedures to disseminate plant parameter data points to the effected Emergency Response Facilities until the U-2 PPC is restored. MIDAS (Meteorological Data) transmission will remain functional during the maintenance window. The Unit 2 ERDS data will not be available during the power outage from 02/27/2013 to 03/04/2013. All work associated with this plant data network software installation will be performed in an expeditious manner consistent with the goal of minimizing unavailability of the systems listed above. ERDS was functionally tested before the outage and will be in service as soon as power is restored. The licensee will notify the NRC Resident Inspector.
ENS 4876317 February 2013 15:51:00Calvert CliffsNRC Region 1CECCNPP (Calvert Cliffs Nuclear Power Plant) U-2 discovered during the Mode 3 NOP/NOT containment walkdown that 2CV-100F Pressurizer Spray valve had a pin hole leak on the leak-off welded cap. This indicates that the bellows has a leak and in addition, the packing is leaking, pressurizing the leak-off line thus the leak-off line is the pressure boundary making this pressure boundary leakage. Technical Specification 3.4.13 (Action B) requires the unit be in mode 3 in 6 hrs. Unit was in mode 3 when discovered and unit will be placed in mode 5 within 36 hrs. Currently, the plant is at 400 degrees and 950 PSIA. The licensee has notified the NRC Resident Inspector.
ENS 487206 February 2013 11:21:00Calvert CliffsNRC Region 1CE

This report is being made in accordance with 10CFR50.72(b)(3)(xiii). Calvert Cliffs Nuclear Power Plant will perform planned maintenance on the Unit 2 Plant Process Computer (PPC) and associated network infrastructure on February 06, 2013. The maintenance will remove the Unit 2 PPC for a planned duration of 12 hours and will render the Unit 2 SPDS out of service for this timeframe. Once the maintenance starts, the effected equipment and functions, including SPDS, can be returned to service within five minutes, if required. 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 at all times. Control room emergency response personnel will use emergency response procedures to disseminate plant parameter data points to the affected Emergency Response Facilities until the U-2 PPC is restored. MIDAS (Meteorological Data) and Unit 2 ERDS (Emergency Response Data System) data transmission will remain functional during the maintenance window. All work associated with this plant data network software installation will be performed in an expeditious manner consistent with the goal of minimizing unavailability of the systems listed above. Back-out criteria has been identified as part of the work package. A test of all systems will be performed at the completion of the upgrade. The licensee notified the NRC Resident Inspector.

  • * * UPDATE AT 1713 EST ON 2/6/2013 FROM AMY CORDNER TO MARK ABRAMOVITZ * * *

The plant process computer was returned to service at 1700 EST. The licensee will notify the NRC Resident Inspector. Notified the R1DO (Powell).

ENS 4860318 December 2012 14:36:00Calvert CliffsNRC Region 1CE

Calvert Cliffs Nuclear Power Plant will begin a planned modification of the Unit 1 and Unit 2 Plant Process Computers (PPC's) and associated network infrastructure on December 18, 2012. This includes the Emergency Response Data System (ERDS) communication with the NRC Operations Center. This work will require the TSC, OSC and subsequently EOF to lose data flow from the plant data network for a period of approximately 36 hours. During this time, the following systems will be impacted for the duration of maintenance: 1. ERDS will be out of service. 2. Plant Data will not reach the TSC and OSC from the plant data network. 3. TSC Computer data transfer to the EOF only will be out of service. 4. Chemistry DAS remote monitoring capability will be lost. 5. Plant parameter data will not be available on the site's LAN network. Once the schedule 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 retrieve plant data inputs to assess plant conditions and perform core damage assessment. Control Room Emergency response personnel will use emergency response procedures (ERPIP 106) to disseminate plant parameter data to the effected Emergency Response Facilities. MIDAS (Meteorological Data) will continue to be operational at the site. Compensatory measures exist within the Calvert Cliffs Emergency Response procedures to provide plant data in the event of an actual Emergency to the NRC Operations Center until the ERDS can be returned to service. The licensee notified the NRC Resident Inspector.

  • * * UPDATE FROM BRIAN HAYDEN TO S. SANDIN ON 12/20/2012 AT 1035 EST * * *

On 12/20/2012 at 0200 EST, the plant process computer and associated network infrastructure was restored to service. The licensee will notify the NRC Resident Inspector. Notified the R1DO (Hunegs).

ENS 4844625 October 2012 17:13:00Calvert CliffsNRC Region 1CEA non-licensed employee supervisor had a confirmed positive for alcohol during a random fitness for duty test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The NRC Resident Inspector has been notified.
ENS 483673 October 2012 07:25:00Calvert CliffsNRC Region 1CE

At 0010 (EDT) on 10/3/12, it was determined that an unanalyzed condition existed for the switchgear rooms on Unit 1. A degraded condition of a high energy line break (HELB) barrier was created during security surveillance. A HELB barrier door for the 27' elevation switchgear room was partially opened for a 14 minute period and could have allowed steam from a HELB on the 27' elevation of the Turbine Building to potentially impact equipment in both the 27' and 45' elevation switchgear rooms because these rooms are connected by a common ventilation system. The switchgear rooms are not analyzed for a steam environment. The degree of the impact could not be readily determined, but could likely affect the safety related equipment in the switchgear rooms. At 0024 (EDT) on 10/3/12, the HELB barrier door for the 27' elevation switchgear room was closed and the barrier restored which eliminated the potential unanalyzed condition. An 8 hour report to the NRC is required under 10 CFR 50.72(b)(3)(ii)(B), 'Any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety' since there was not a reasonable expectation that the switchgear room environment could support operation of safety related equipment with the 27' elevation switchgear room door partially open. Further analysis is underway. The licensee has notified the NRC Resident Inspector.

  • * * RETRACTION FROM CHARLES MORGAN TO HOWIE CROUCH AT 1241 EST ON 11/19/12 * * *

Subsequent engineering analysis conducted for this condition demonstrated that having the roll-up door stuck open six inches would not, should a HELB occur in the vicinity of the 27' switchgear room roll-up door, result in conditions within both switchgear rooms that would challenge the design limits and which would render the Class 1E electrical busses inoperable. Therefore the unit was not in a degraded or unanalyzed condition. As a result this condition is not reportable under 50.72(b)(3)(ii)(B). Based on this information, Calvert Cliffs is retracting notification message EN #48367. The licensee has notified the NRC Resident Inspector. Notified R1DO (Dwyer).

ENS 483683 October 2012 07:25:00Calvert CliffsNRC Region 1CE

This report is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the planned loss of an Emergency Response Facility (ERF). Calvert Cliffs will be implementing a scheduled modification to renovate the site's common Technical Support Center (TSC) which will temporarily remove it from service. The planned maintenance window is expected to be three weeks beginning on 10/3/12 and concluding on 10/26/12. Should an emergency be declared requiring TSC activation during this period, the procedurally identified alternate TSC will be staffed and activated (CCNPP Simulator). All TSC responders and other key ERO personnel have been briefed on this activity and the applicable contingency actions that will be required to be taken in their specific emergency response procedures. This condition has no adverse impact to the health and safety of the public. An update will be provided once the TSC has been restored to normal operation. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE FROM TOM JONES TO DONG PARK AT 1302 EDT ON 10/26/12 * * *

The TSC has been restored to normal operation. The licensee will notify the NRC Resident Inspector. Notified R1DO (Caruso).

ENS 4825230 August 2012 00:31:00Calvert CliffsNRC Region 1CECalvert Cliffs Unit 2 Primary Plant Computer (PPC) is out of service. The PPC provides monitoring capability for the Emergency Response Data System and Safety Parameter Display System. The loss of the PPC requires alternate monitoring methods, as described in plant procedures, to be used. Therefore, appropriate assessment of plant conditions, notifications and communications can still be made, if required, during the time that the PPC is unavailable. This report is being made in accordance with 10 CFR 50.72(b)(3)(xiii) which is any event that results in major loss of emergency assessment capability, offsite response capability, or offsite communications capability. As previously stated, alternate means remain available to assess plant conditions, make notifications and accomplish required communications, as necessary. The licensee has notified the NRC Resident Inspector.
ENS 4823326 August 2012 17:05:00Calvert CliffsNRC Region 1CEThe Calvert Cliffs control room was notified at 1530 EDT on 8/26/2012 by a site employee that Siren C15 was intermittently alarming. This is a repeat of a similar actuation that had been reported in EN #48231. The licensee has notified the Calvert County Control Center that the siren had actuated. The licensee has deactivated the siren until further investigation and repairs can be accomplished. As was noted in the original event, adverse inclement weather conditions existed at the time the siren was alarming. The licensee notified the NRC Resident Inspector.
ENS 4823126 August 2012 02:41:00Calvert CliffsNRC Region 1CECalvert Cliffs control room was notified at 0110 EDT on 8/26/2012 by the Calvert Control Center (911) that sirens in the Calvert County area were activated. Reports were narrowed down to Lloyd Bowen Rd, Siren C15. At this time the siren is believed to be getting water in the controls due to inclement weather in the area. Maintenance Support is on their way to locally confirm and isolate the suspect siren. 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 been or will be made.' The licensee notified the NRC Resident Inspector. See related EN #48233.
ENS 4818312 August 2012 14:37:00Calvert CliffsNRC Region 1CECalvert Cliff Nuclear Power Plant, Unit 1 Control Element Assembly (CEA) #9 fully inserted (CEA dropped) into the core. Technical Specification 3.1.5, Action B was entered and requires the CEA to be realigned within 2 hours. With this action not met Technical Specification 3.1.5, Action C requires the Unit be placed in Mode 3 within 6 hours. A plant shutdown has been initiated in accordance with this Technical Specification. Therefore, this is reportable under 10 CFR 50.72. (b) (2) (i) Plant Shutdown Required by Technical Specifications. The licensee has notified the NRC Resident Inspector. The licensee will also notify local government agencies.
ENS 4812421 July 2012 13:10:00Calvert CliffsNRC Region 1CE(Calvert Cliffs Nuclear Power Plant) CCNPP U1 identified RCS Pressure Boundary Leakage from the instrument line to 1-PDT-123A, 11A reactor coolant pump differential pressure transmitter. Technical Specification 3.4.13, Action B was entered and requires that the Unit be placed in Mode 3 within 6 hours and Mode 5 within 36 hours. (The licensee has) initiated plant shutdown in accordance with this Technical Specification. Therefore, this is reportable under 10CFR50.72(b)(2)(i) Plant Shutdown Required by Technical Specifications. This is also reportable under 50.72(B)(3)(ii)(A) as a material defect in the primary coolant system that cannot be found acceptable under ASME Section XI, IWB-3600 or ASME Section XI, Table IWB-3410-1. The leak is from an instrument line which monitors reactor coolant pump differential pressure. It is for monitoring purposes only. The leak rate is currently about .08 gpm. The licensee has begun power reduction of the unit and is currently at approximately 73% rated thermal power. The recovery plan is to complete the unit shutdown and then enter containment and repair the leak. The leak is believed to be coming from the same instrument line that was reported to be leaking on July 17, 2012 (see EN #48116). At that time, power was reduced to approximately 10% and a containment entry was made. At that time it was believed that the leak had been isolated and full power operations were resumed. Based on containment sump pump run times and another containment entry, it was determined that the leak apparently had not been isolated. The licensee notified the NRC Resident Inspector.
ENS 4811617 July 2012 19:32:00Calvert CliffsNRC Region 1CEAt 1715 EDT on July 17th, 2012, Calvert Cliffs Nuclear Power Plant Unit 1 identified RCS Pressure Boundary Leakage from the instrument line to 1-PDT-123A, 11A reactor coolant pump differential pressure transmitter. Technical Specification 3.4.13, Action B was entered and requires that the Unit be placed in Mode 3 within 6 hours and Mode 5 within 36 hours. The licensee has initiated plant shutdown in accordance with this Technical Specification. Therefore, this is reportable under 10 CFR 50.72(b)(2)(i) Plant Shutdown Required by Technical Specifications. This is also reportable under 50.72(B)(3)(ii)(A) as a material defect in the primary coolant system that cannot be found acceptable under ASME Section XI, IWB-3600 or ASME Section XI, Table IWB-3410-1. The licensee initially discovered the leak during an RCS leak rate surveillance that indicated RCS leakage on the order of 0.08 gpm. A video camera was used to look for the leak and was found to be on the identified instrument line. The licensee has initiated a power reduction and is currently at approximately 50%. The recovery plan at this time is to reduce power to about 10% which will reduce radiation levels in the area of the leak and isolate the instrument line and isolate the leakage. The instrument line is for a reactor coolant pump differential pressure transmitter which is for monitoring purposes only and does not provide any safety related functions. If the leak can be secured, the licensee intends to return to power. If the leak cannot be secured, the plant will shutdown in compliance with the technical specification action statement. The licensee has notified the NRC Resident Inspector.
ENS 4808711 July 2012 02:23:00Calvert CliffsNRC Region 1CEA '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 480736 July 2012 08:24:00Calvert CliffsNRC Region 1CE

Calvert Cliffs Tech Support Computer power supply failed rendering the ERDS system 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 licensee notified the NRC Resident Inspector.

  • * * UPDATE FROM JOE JIOFFRE TO HOWIE CROUCH AT 1528 EDT ON 7/7/12 * * *

ERDS was returned to service at 1528 EDT after replacing the computer power supply. The licensee has notified the NRC Resident Inspector. Notified R1DO (Henderson).

ENS 4769926 February 2012 20:15:00Calvert CliffsNRC Region 1CE

Calvert Cliffs will be performing planned maintenance to the U-1 Plant Process Computer to install isolation transformers. This maintenance window was expected to start at 2100 (EST) today, 2/26/2012, but the U-1 Plant Process Computer failed at 1546 this afternoon and it was decided to commence the planned maintenance window at that time versus spending resources to attempt recovery of the computer for just a short time period. The planned maintenance window is expected to be 54 hours long and end February 28, around 2300. This will impact the Unit 1 data dissemination to the Safety Parameter Display System (SPDS), TSC Computer. PI (Plant Trending Software) and ERDS will also be 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. MIDAS (Meteorological Data) will continue to be operational at the site. Applicable Reporting Requirement: 10 CFR 50.72 (b) (3) (xiii); 8 Hour report. The licensee notified the NRC Resident Inspector.

  • * * UPDATE AT 1209 EST ON 03/01/12 FROM JAY GAINES TO S. SANDIN * * *

At 1000 (EST) this morning planned maintenance was completed to the Unit 1 plant process computer. All plant assessment capabilities have been restored. The licensee informed the NRC Resident Inspector. Notified R1DO (Ferdas).

ENS 4768422 February 2012 13:58:00Calvert CliffsNRC Region 1CECalvert Cliffs will be performing planned U-1 Refueling Outage maintenance to a portion of the sites 1E Electrical Distribution System. This maintenance window is expected to be 36 hours long and will start at 1400 today. This will impact the dissemination of plant data to the TSC, EOF, and OSC. ERDS will also be 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. MIDAS (Meteorological Data) will continue to be operational at the site. The licensee notified the NRC Resident Inspector.
ENS 476323 February 2012 08:22:00Calvert CliffsNRC Region 1CELOSS OF PLANT COMMUNICATIONS DUE TO SCHEDULED MAINTENANCE

"Calvert Cliffs will be implementing scheduled maintenance to the plant data network to install a data diode to meet the new cyber security requirements listed in 10 CFR 5.71. This work will require the TSC, OSC and subsequently the EOF to lose normal data flow from the plant data network for a period of approximately 6 to 8 hours. ERDS will also be unavailable during this maintenance. 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. MIDAS (Meteorological Data) will continue to be operational at the site."

The licensee notified the NRC Resident Inspector.
ENS 4761923 January 2012 20:59:00Calvert CliffsNRC Region 1CE

At 1300 EST on 1/23/12, it was determined that an unanalyzed condition existed for the Unit 1 Cable Spreading Room. A high energy line break (HELB) barrier issue was discovered while performing a HELB inspection and the condition is believed to have existed from initial plant construction. A HELB barrier was found to have a breach in it that could allow steam from a high energy line break in the Unit 1 Turbine Building (into the cable spreading room and thus into the control room). The Control Room is not analyzed for a steam environment. The degree of the impact could not be readily determined, but could likely affect the safety related equipment in the Cable Spreading Room. Therefore, an 8-hour report to the NRC is required under 10 CFR 50.72(b)(3)(ii)(B), 'Any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety.' The licensee will notify the NRC Resident Inspector.

  • * * RETRACTION ON 1/26/2012 AT 1339 EST FROM ROBERT MARTIN TO MARK ABRAMOVITZ * * *

Engineering performed an evaluation to address the impact of the degraded condition on the barrier's design functions. The evaluation concluded that the barrier remained capable of performing its design function with the degraded seal present. Therefore, this condition does not represent an unanalyzed condition that significantly degrades plant safety. The NRC Resident Inspector has been notified. Notified the R1DO (Dentel).

ENS 475129 December 2011 00:21:00Calvert CliffsNRC Region 1CE

At 1755 on 12/8/11, it was determined that an unanalyzed condition existed for the common Control Room for both Units. A high energy line break (HELB) barrier issue was discovered while performing a fire barrier surveillance and the condition is believed to have existed from initial plant construction. A HELB barrier was found to have a significant breach in it that could allow steam from a HELB in the Unit 2 Steam Generator Blowdown system to potentially impact equipment in the Control Room. The Control Room is not analyzed for a steam environment. The degree of the impact could not be readily determined, but could likely affect the safety related equipment in the Control Room. At 1803 on 12/8/11, Unit 2 Steam Generator Blowdown was secured to eliminate the potential for a HELB in the affected area which eliminated the potential unanalyzed condition. Therefore, an 8 hour report to the NRC is required under 10 CFR 50.72(b)(3)(ii)(B) 'Any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety' since there was not a reasonable expectation that the Control Room environment could support operation of safety related equipment with Unit 2 Steam Generator Blowdown in service. Further analysis is underway. The licensee will notify the NRC Resident Inspector

  • * * RETRACTION AT 0059 EST ON 2/7/12 FROM KENT MILLS TO HUFFMAN * * *

Engineering performed an evaluation to address the impact of the degraded condition on the barrier's design functions. The evaluation concluded that the barrier remained capable of performing its design function with the degraded seal present. Therefore, this condition does not represent an unanalyzed condition that significantly degrades plant safety. The licensee will notify the NRC Resident Inspector. R1DO (Burritt) notified.

ENS 474133 November 2011 23:26:00Calvert CliffsNRC Region 1CE

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.

  • * * RETRACTION ON 12/29/11 AT 1556 EST FROM GIOFFRE TO HUFFMAN * * *

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 473163 October 2011 14:45:00Calvert CliffsNRC Region 1CEDual Unit Shutdown due to T.S. 3.0.3. Unit 1 and Unit 2 'A' Train Emergency Diesel Generators (EDGs) OOS (Out-of-Service). '2A' DG OOS due to '21' Salt Water Header scheduled maintenance. '1A' DG OOS due to emergent loss of '16' Battery charger for the '1A' DG DC bus. Neither '11' nor '22' 125 VDC busses have an Operable charger. (Chargers have power, but do not have an Operable DG). " The licensee entered TS 3.0.3 at 1035 EDT and is expected to be in Mode 3 on both units at 1735 EDT unless the licensee exits T.S. 3.0.3 upon restoration of the battery charger. '0C' EDG is functional but not credited towards T.S. The salt water header is not expected to be restored until 10/4/11. There are no issues with offsite power. The NRC Resident Inspector has been notified. The licensee will notify the Calvert Control Center and plans to make a press release. CR No.: CR-2011-009860; Calvert Cliffs internal event notification number 4194.