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 Entered dateSiteRegionReactor typeEvent description
ENS 5623622 November 2022 17:35:00MonticelloNRC Region 3GE-3The following information was provided by the licensee via email: On 11/22/2022, Monticello Nuclear Generating Plant initiated a voluntary communication to the State of Minnesota after receiving analysis results for an on-site monitoring well that indicated tritium activity above the (Offsite Dose Calculation Manual) ODCM and Nuclear Energy Institute (NEI) Groundwater Protection Initiative (GPI) reporting levels. The source of the tritium is under investigation and the station will continue to monitor and sample accordingly. This notification is being made solely as a four-hour, non-emergency report for a Notification of Other Government Agency. This event is reportable in accordance with 10 CFR 50.72(b)(2)(xi). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 562104 November 2022 17:10:00Quad CitiesNRC Region 3GE-3The following information was provided by the licensee via email: On November 4, 2022, at 1400 hours, with Unit 2 (U2) in Mode 1 at 100 percent power, a manual scram was inserted on U2 due to rising reactor water level, which occurred following an unexpected opening of the 2B Feedwater Regulating Valve. Following the reactor scram, reactor water level decreased to approximately 0 inches, which resulted in an automatic Group II and Group III isolation (expected response). Reactor Water Level control has been established in a normal band. The cause and details of the event are under investigation. The Unit 2 scram was not complicated. Operations responded using the Emergency Operating Procedures and stabilized the plant in mode 3. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Unit 1 was unaffected by the event and remains at 100 percent power. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5602330 July 2022 04:00:00DresdenNRC Region 3GE-3

The following information was provided by the licensee via email: At 2217 CDT on 7/29/22, cribhouse suction bay levels were reported less than 501.5 feet due to buildup of grass on bar racks. Ultimate Heat Sink (UHS) is INOPERABLE due to Surveillance Requirement 3.7.3.1 not met. ENTER Technical Specification (TS) 3.7.3 condition A (Required Action (RA) A.1 mode 3 in 12 hours, RA A.2 mode 4 in 36 hours). Dresden Lockmaster reports river level normal at 504.89 feet. Commenced trash rake operations to clear grass debris off of intake bar racks. At 0135 CDT on 7/30/22, cribhouse suction bay levels were reported at greater than 501.5 feet. Exit TS 3.7.3 condition A. Due to this INOPERABILITY, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(B). There was no impact on the health and safety of the public or plant personnel. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee notified the NRC Resident Inspector.

  • * * UPDATE ON 7/30/22 AT 1934 EDT FROM COLLIN GRISCHOTT TO BRIAN LIN * * *

At 1116 CDT on 7/30/22, a repeat condition occurred where cribhouse suction bay levels were reported < 501.5 feet due to buildup of grass on bar racks. Entered TS 3.7.3 condition A (RA A.1 mode 3 in 12 hours, RA A.2 mode 4 in 36 hours). Actions are in-progress to clear grass debris off the intake bar racks. Due to this INOPERABILITY, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(B). At 1745 CDT on 7/30/22, cribhouse suction bay levels were reported at >501.5 feet. Exit TS 3.7.3 condition A. The station continues to monitor for intake grass buildup and taking appropriate actions to maintain UHS operability. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee notified the NRC Resident Inspector. Notified R3DO (Peterson).

ENS 5598812 July 2022 11:47:00DresdenNRC Region 3GE-3The following information was provided by the licensee via fax or email: At 0803 EDT on 7/12/2022, with the Unit 2 in Mode 1 at 100% power, an automatic scram was received on Unit 2 following a turbine trip due to high reactor water level. The trip was uncomplicated with all systems responding normally post trip. All rods inserted to their full-in positions. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). The cause of the transient is under investigation. Operations responded using the Emergency Operating Procedure and stabilized the plant in Mode 3. Decay heat is being removed using the steam bypass valves to the condenser and the safety relief valves did not lift as a result of the trip. Reactor vessel inventory and pressure are being maintained in normal control bands. Unit 3 was not affected by this transient. There was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 559764 July 2022 09:53:00Quad CitiesNRC Region 3GE-3The following information was received from the licensee via email: At 0130 CDT on July 4 2022, it was discovered both trains of Standby Gas Treatment System were simultaneously inoperable due to failure to reach required flow rates. Both trains were capable of starting but failed to reach the required flow of 4000 SCFM. Secondary Containment differential pressure was not able to be maintained at greater than or equal to 0.25 inches of vacuum water gauge, causing Secondary Containment to also be inoperable. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72(b)(3)(v)(D). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 559754 July 2022 05:57:00Quad CitiesNRC Region 3GE-3The following information was received from the licensee via facsimile: On July 4, 2022 at 0104 CDT, with Unit 2 in Mode 1 at 100 percent power, a manual scram was inserted on U2 due to lowering reactor water level, which occurred following an unexpected closure of the 2A Feedwater Regulating Valve. Following the reactor scram, reactor water level decreased to approximately minus 16 inches, which resulted in an automatic Group II and Group III isolation (expected response). Following the scram, reactor water level rose to plus 75 inches resulting in a trip of all three Reactor Feedwater Pumps. At 0114 CDT, Reactor Water Level lowered to less than the Feedwater Pump High Level Trip setpoint and the 2C Reactor Feedwater Pump was restarted. Reactor Water Level control has been established in a normal band. The cause and details of the event are under investigation. The Unit 2 scram was not complicated. Operations responded using the Emergency Operating Procedure and stabilized the plant in mode 3. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Unit 1 was unaffected by the event and remains at 100 percent power. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee will notify the Illinois Emergency Management Agency.
ENS 559221 June 2022 13:58:00Quad CitiesNRC Region 3GE-3The following information was provided by the licensee via email followed by phone call: At approximately 1043 CDT, the Quad Cities Main Control Room was notified that the Scott County Iowa warning sirens were activated in error at 1001 CDT. The sirens were not intentionally activated to notify the public of severe weather or pending emergency. This event is reportable per 10 CFR 50.72(b)(2)(xi), News Release or Notification of Other Government Agencies. This is a 4-Hour Reporting requirement. The Quad Cities NRC Resident has been notified.
ENS 5589613 May 2022 17:47:00MonticelloNRC Region 3GE-3The following information was provided by the licensee via email: On 5/13/22 at 1111 CDT the station entered LCO 3.7.4 Condition B for Control Room Envelope being inoperable. This was due to results from an inspection in the Steam Jet Air Ejector room that identified steam leakage exceeding the leakage rate assumptions made in the Alternate Source Term (AST) dose analysis calculation. Therefore, this is being reported in accordance with 10CFR50.72(b)(3)(ii)(B) for an unanalyzed condition that significantly degrades plant safety and 10CFR50.72(b)(3)(v)(D) for any event or condition that at the time of discovery could have prevented fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. There is no impact to the health and safety of the public. NRC Resident has been notified.
ENS 5589110 May 2022 23:42:00Quad CitiesNRC Region 3GE-3

The following information was provided by the licensee via fax: At 1359 CDT on May 10, 2022, the 1B LPCI Loop Upstream Injection valve (1-1001-28B) was found to have a motor operated torque switch issue and inadequate lubrication. This issue called into question the ability of the valve to close when required. At 1746 CDT on May 10, 2022, both trains of Unit 1 LPCI were made simultaneously inoperable. TS 3.6.1.3 Condition A required de-activation of 1B LPCI Loop Downstream Injection valve (1-1001-29B) which was completed at 1746 CDT. Because of the de-activation of the 1B LPCI Loop downstream injection valve and LPCI Loop select logic, both trains of LPCI were made inoperable. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(V). Unit 1 HPCI and both loops of Core Spray are operable. After further engineering review, it was determined that 1B LPCI Loop Upstream injection valve condition was minor in nature and would not have affected the ability of the valve to close when required. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.

  • * * UPDATE AT 12:32 EDT ON 05/11/22 FROM MARK HUMPHREY TO BRIAN P. SMITH * * *

The following information was provided by the licensee via phone call and email: The last sentence in the second paragraph, "After further engineering review, it was determined that 1B LPCI Loop Upstream injection valve condition was minor in nature and would not have affected the ability of the valve to close when required," has been deleted. The licensee is continuing to follow up on the issue and believes that sentence to be unclear and premature. Notified R3DO (Skokowski).

ENS 5584415 April 2022 11:31:00PilgrimNRC Region 1GE-3The following information was provided by the licensee via email: On April 15, 2022 at 1000 hours (EDT), four off-site notifications were made to the Commonwealth of Massachusetts Department of Environmental ÿProtection (MADEP) in accordance with the Massachusetts Contingency Plan (310 CMR 40.0000). ÿThe notifications document non-radiological contaminants found slightly above reportable concentrations in select soil and groundwater samples collected during site characterization efforts, as part of the decommissioning process, from four parcels of land at the property.ÿ ÿReportable concentrations in soil were identified in a composite sample for Polychlorinated Biphenyls (PCBs). ÿReportable concentrations in groundwater were identified in samples for per- and polyfluoroalkyl substances (PFAS) and Semi Volatile Organic Compound (SVOC). Additionally, the reports include sample results where laboratory reporting limits equaled or exceeded reporting thresholds. This notification is being made solely as a four-hour, non-emergency notification for a Notification of Other Government Agency in accordance with 10 CFR 50.72(b)(2)(xi).ÿ There was no impact on the health and safety of the public or plant personnel. The NRC Lead Decommissioning Inspector and NMSS Project Manager assigned to Pilgrim have been notified.
ENS 557211 February 2022 15:23:00DresdenNRC Region 3GE-3The following information was provided by the licensee via fax or email: At approximately 1025 CST, the Dresden Main Control was notified of Grundy County warning sirens issues during the intended monthly test. The Grundy County scheduled monthly siren test had issues with siren activation from the County's primary controller. The buttons to activate were being pressed but the intended sirens were not initiating. The Grundy County operator continued to attempt activation unknowingly activating the sirens in the northeast quadrant between 1000-1015 CST. This event is reportable per 10 CFR 50.72(b)(2)(xi), News Release or Notification of Other Government Agencies. This is a 4-Hour Reporting requirement. The Dresden NRC Resident has been notified.
ENS 5570821 January 2022 10:25:00MonticelloNRC Region 3GE-3The following information was provided by the licensee via email: This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation of secondary containment relays in accordance with 10 CFR 50.73(a)(2)(iv)(A). On November 29, 2021, the `B' Fuel Pool radiation monitor spiked high during restoration following the performance of the 0068 procedure `Spent Fuel Pool & Reactor Building Exhaust Plenum Monitor Calibration' due to cable to radiation monitor connector degradation from handling. This resulted in a Partial Primary Containment Group II isolation (gas systems), initiation of Standby Gas Treatment system, and isolation of the Reactor Building Ventilation system. All systems responded as designed to the actuation signal. Operations reset the Partial Primary Containment Group II isolation signal, shutdown Standby Gas Treatment System, and restored Reactor Building Ventilation system per procedures. At the time of the occurrence, the `A' Fuel Pool radiation monitor was reading normal at approximately 1.5 mr/hr. The `B' Fuel Pool radiation monitor spiked above the 50 mr/hr setpoint and continued to read erratically. Work was performed to clean and reconnect the connector and testing per 0068 procedure verified the condition was corrected. The `B' Fuel Pool radiation monitor returned to service. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 556192 December 2021 00:58:00Quad CitiesNRC Region 3GE-3At 1847 CST on December 1, 2021, it was discovered that the HPCI (high pressure coolant injection) system was inoperable. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). The Unit 1 RCIC (reactor core isolation cooling) system was Operable during this time period. There was no impact on the health and safety of the public or plant personnel. The NRC Resident has been notified. Unit 1 HPCI operability was restored at 2110 CST.
ENS 555679 November 2021 13:33:00PilgrimNRC Region 1GE-3At 1040 hours EST, November 9, 2021, the site reported a violation of the station National Pollutant Discharge Elimination System permit. The 24-hour environmental report addressed an unauthorized discharge of 7,245 gallons of non-radiological water that was pumped into a storm drain to de-water an on-site electrical vault located outside of the protected area. This discharge occurred from 0800 to 1230 hours on November 8, 2021. Sampling and analysis of the vault water is in progress to assess for the presence of pollutants. This notification is being made solely as a four-hour, non-emergency notification for a Notification of Other Government Agency. This event is reportable in accordance with 10 CFR 50.72(b)(2)(xi). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The licensee notified the U.S. Environmental Protection Agency and the Commonwealth of Massachusetts Department of Environmental Protection.
ENS 5552816 October 2021 09:10:00DresdenNRC Region 3GE-3On October 16, 2021 at 0428 CDT, an automatic scram was received on Unit 3 following a turbine trip. All Rods inserted to their full in position. All systems actuated and operated as expected. Unit 3 is being maintained in Mode 3, hot standby. This event is being reported pursuant to 10CFR 50.72(b)(2)(iv)(B), any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical. The NRC Resident Inspector has been notified. The event is related to Event Number 55527.
ENS 5552716 October 2021 07:22:00DresdenNRC Region 3GE-3

(An) Unusual Event (was declared) due to a fire in the protected area not extinguished in less than 60 minutes. Main power transformer 3 faulted, the unit auto scrammed, all rods are in. The fire went out at 0622 CDT. (The licensee) is monitoring for re-flash. The unit automatically scrammed and all rods fully inserted. Decay heat removal is through the condenser. Unit 2 is unaffected and remains at 100 percent power. The licensee notified the NRC Resident Inspector and R3 Branch Chief (Riemer). Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), and DHS Nuclear SSA (email).

  • * * UPDATE ON 10/16/21 AT 0848 EDT FROM DAVID KIJOWSKI TO BETHANY CECERE * * *

The Unusual Event was terminated at 0709 CDT. Notified R3DO (Pelke), NRR EO (Felts), IR MOC (Kennedy), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), and DHS Nuclear SSA (email).

ENS 553963 August 2021 19:48:00DresdenNRC Region 3GE-3At approximately 1539 CDT on 8/3/2021, the Dresden Station Main Control was notified of the inadvertent actuation of 17 full sounding emergency response sirens affected Dresden Station in Will County Illinois, while testing other sirens. Will County EMA inadvertently actuated the sirens on 8/3/2021 at 1440 CDT. This event is reportable per 10 CFR 50.72(b )(2)(xi), News Release or Notification of Other Government Agencies. This is a 4-Hour Reporting requirement. The Dresden NRC Resident has been notified. See related Event Notification #55395.
ENS 552447 May 2021 17:21:00MonticelloNRC Region 3GE-3The following is a summary of information received via email from Monticello Nuclear Generating Plant (MNGP): On March 9, 2021, GE Hitachi (GEH) issued Safety Communication SC 21-02 for PRC 21-02, Transfer of Information, Revision 0, pursuant to 10 CFR 21.21(b). Monticello Nuclear Generating Plant (MNGP) was listed as a potentially affected plant. This is a deviation from the Power Range Nuclear Monitor (PRNM) Licensing Topical Report, NEDC 32410P-A. On May 5, 2021, MNGP completed an evaluation of this deviation and concluded this condition represents a substantial safety hazard in that the condition could result in an Average Power Range Monitoring (APRM) flux reading either below or above the Technical Specification (plus/minus) 2% band. The condition is a defect that is reportable pursuant to 10 CFR 21.21(d)(4). The GEH NUMAC PRNMS was installed in 2009 with System Part No. 299X739NF. Name and Address of the Individual or Individuals Informing the Commission: Thomas A. Conboy, Site Vice President Monticello Nuclear Generating Plant Northern States Power Company - Minnesota 2807 West County Road 75 Monticello, MN 55362 The licensee notified the NRC Resident Inspector.
ENS 5520221 April 2021 09:45:00PilgrimNRC Region 1GE-3On April 21, 2021, at 0752 hours (EDT), an offsite notification was made to the Commonwealth of Massachusetts Department of Environmental Protection (MADEP) in accordance with Regulation 310 CMR 40.0000: Massachusetts Contingency Plan (MCP). The notification documents non-radiological contaminants found above reportable concentrations in select samples collected during site characterization efforts. The reported reportable concentrations were slightly above reporting limits in a soil sample for Per and Polyfluoroalkyl Substances (PFAS), two groundwater sampling locations for PFAS, and isolated instances of metals in groundwater including Arsenic, Vanadium, Lead, Antimony, Beryllium, Cadmium, Chromium, Nickel, and Thallium. This report is being submitted in accordance with 10CFR50.72(b)(2)(xi) based on notification being made to another government agency. Concentrations above reporting limits have been entered into the site's corrective action program. As per MCP, the site will proceed with requirements to implement the phased MCP process. This condition does not represent a threat to station personnel or to members of the general public.
ENS 5514620 March 2021 04:55:00Quad CitiesNRC Region 3GE-3At 20:30 CDT on March 19, 2021, with the Unit 1 in Mode 5 at 0 percent power, an actuation of the Unit 1 Emergency Diesel Generator (EDG) occurred during outage activities on Transformer 12 (T-12) resulting in a trip. The cause of the Unit 1 EDG auto-start was bus undervoltage as a result of the T-12 trip. The Unit 1 EDG automatically started as designed when the Bus 14-1 undervoltage signal was received. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Unit 1 EDG. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5513210 March 2021 18:26:00Quad CitiesNRC Region 3GE-3On March 10, 2021, Exelon reported an unpermitted release of a radionuclide (i.e., tritium) into the groundwater within the site boundary at Quad Cities Nuclear Power Station to the Illinois Environmental Protection Agency (IEPA) and the Illinois Emergency Management Agency (IEMA) in accordance with Illinois state regulations. There has been no detection of the release beyond the site boundary. The suspected source for the increased groundwater tritium levels is an onsite water storage tank or pipe; however, an investigation is in progress and the exact cause and source is not yet known. The increase in groundwater tritium concentration does not exceed any NRC regulations or reporting criteria. This notification is being made solely as a four-hour, non-emergency notification for a Notification of Other Government Agency. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5507118 January 2021 17:31:00PilgrimNRC Region 1GE-3On January 18, 2021 at 1600 hours (EDT), Holtec Decommissioning International (HDI) made an off-site notification to the Environmental Protection Agency's Enforcement and Compliance Assurance Division in accordance with Section B of the station's National Pollutant Discharge Elimination System (NPDES) Permit No. 0003557. The event was associated with an underground sewage water system holding tank. The specific details of the occurrence are as follows: On January 13, 2021 at 1000 hours (EDT) site personnel identified what appeared to be water bubbling up from an unidentified cover within the security protected area of the site. The water emanating from the cap had no visible color or solid material and no odor. The water estimated at 25 gallons per hour or less was flowing to a site storm drain connected to permitted outfall number 007. Initial indication was that the water was potable water as part of the station's fire protection system. Further investigation determined that a back-up in an underground sewage holding tank inlet was the source of the leakage. By 1400 hours (EDT) when bathrooms including toilets on site were shutdown and removed from service, efforts were underway to pump the tank and remove the blockage, and the bubbling from the cover had stopped. The licensee has notified the Massachusetts Environmental Protection Agency, the Massachusetts Emergency Management Agency and the NRC Resident Inspector.
ENS 549388 October 2020 13:14:00MonticelloNRC Region 3GE-3

At 1125 CDT on 10/8/20 Monticello Nuclear Generating Plant declared a Notification of an Unusual Event (NOUE) due to a Security Condition that did not involve a hostile action, due to a helicopter that hovered over the site for approximately 10 minutes. The unit remained at 100 percent power during the event. The licensee notified the NRC Resident Inspector, the Minnesota State Duty Officer and the Wright County and Sherburne County Sherriff departments of the event. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

  • * * UPDATE ON 10/8/2020 AT 2013 EDT FROM JEFF OLSON TO JEFFREY WHITED * * *

At 1715 CDT Monticello Nuclear Generating Plant terminated the Notice of Unusual Event (HU1.1), upon confirmation through federal law enforcement and conversation with the aircraft owner that the aircraft in question was performing power line inspections for a different utility and was not a threat to the plant. Monticello determined that this condition did not meet the 1-hour reporting requirements of 10 CFR 73.71. Notified R3DO (Orlikowski), NRR EO (Miller), and IRD MOC (Gott). Additionally, notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

  • * * RETRACTION ON 10/28/20 AT 1436 EDT FROM JACOB BURSKI TO BETHANY CECERE * * *

Monticello Nuclear Generating Plant (MNGP) is retracting this event notification based on subsequent information received that was not available at the time of the original notification. Following review of the additional information collected by the site through an investigation performed with input from local and federal law enforcement, Xcel Energy determined the helicopter did not constitute a credible threat or compromise site safety or security. There was no impact to public health or safety. The NRC Resident Inspector has been notified. The licensee will notify the State and county. Notified R3DO (Peterson).

ENS 5329929 March 2018 16:42:00Quad CitiesNRC Region 3GE-3On March 29, 2018, Exelon Generation Company, LLC notified the Illinois Environmental Protection Agency (IEPA) and the Illinois Emergency Management Agency (IEMA) in accordance with state regulations of an unpermitted release of radionuclides at the Quad Cities Nuclear Power Station within the site boundary. There has been no detection of the liquid release beyond the site boundary. No impact to human health or the environment are anticipated. This notification is being made to satisfy 10CFR50.72(b)(2)(xi), notification of the NRC for any event related to the health and safety of the public for which a notification to other government agencies has been or will be made. The source of the Tritium release was from the Rad waste system. The spill was reported to be within the protected area which is within the site boundary. The quantity of the release is unknown at this point as the investigation and spill cleanup is in progress. The Licensee Notified the NRC Resident Inspector.
ENS 5328725 March 2018 23:43:00PilgrimNRC Region 1GE-3

On March 25, 2018 at 1616 hours (EDT), with the reactor in cold shutdown condition, two control rod drive piping lines were determined to be potentially inoperable in the event of a design basis earthquake due to support defects. The control rod drive piping forms a portion of the reactor coolant pressure boundary and primary containment boundary. The supports will be repaired prior to plant startup. This event had no impact on the health and/or safety of the public. The NRC Resident Inspector has been notified. The licensee will notify the Commonwealth of Massachusetts.

  • * * RETRACTION FROM JOE FRATTASIO TO HOWIE CROUCH AT 1500 EDT ON 4/13/18 * * *

The purpose of the notification is to retract ENS notification 53287 made on 03/25/18 for Pilgrim Nuclear Power Station. The previous notification reported that control rod drive (CRD) piping could be potentially inoperable in the event of a design basis earthquake, at the time of discovery, due to piping support defects. Subsequent evaluation has demonstrated that the piping was not inoperable. Specifically, after an engineering evaluation, it has been determined that the CRD Hydraulic System operability was never lost and the system was operable, although non-conforming, based on the support configuration not conforming to the pipe support drawings. The affected pipe supports have been restored or reworked to the proper design condition in accordance with the design drawings. The CRD System has subsequently been restored to a fully operable status. Notified R1DO (Jackson) and IRD MOC (Pham).

ENS 5328523 March 2018 21:07:00MonticelloNRC Region 3GE-3This report is made for a loss of Emergency Assessment Capability associated with Emergency Action Levels for Toxic and Flammable Gas and is reportable under 10 CFR 50.72(b)(3)(xiii). During an emergency equipment inventory, it was identified that methods were not available to detect levels of toxic or flammable gas at the IDLH (Immediately Dangerous to Life and Health) level for a number of substances due to the detector having an unsuitable range. The IDLH is used to assess the Emergency Action Level Alert Range. The ability of the Control Room Staff to detect and respond to the presence of toxic or flammable gas is unaffected. Because there have been no chemical spills or releases that would require sampling to be performed, the health and safety of the public was not affected. The resident NRC Inspector has been notified. The licensee will be notifying the state of Minnesota.
ENS 5325913 March 2018 15:54:00PilgrimNRC Region 1GE-3On March 13, 2018 at 1000 hours (EDT), with the reactor in Cold Shutdown condition, both 345kV incoming power lines and 23 kV Shutdown Transformer became unavailable during the Northeast winter storm. Per procedures, the emergency on-site emergency power supplies (Emergency Diesel Generators) were running and providing power to essential systems. In addition, the back-up Diesel Air Compressor was in service and one Reactor Protection System bus was on the back-up power supply prior to the loss. With both 345kV incoming power lines and 23 kV Shutdown Transformer unavailable, Pilgrim Nuclear Power Station procedures direct a report be made to the NRC per the requirements of Title 10 Code of Federal Regulations 50.72(b)(3)(v), any event that could have prevented the fulfillment of the safety function. No actual loss of safety function has occurred since the on-site emergency power supplies are maintaining the reactor in a safe shutdown condition and removing residual heat. The loss of incoming power is under investigation. This event had no impact on the health and/or safety of the public. The NRC Resident Inspector has been notified.
ENS 532423 March 2018 02:19:00PilgrimNRC Region 1GE-3At 2315 EST on March 2, 2018, Pilgrim Nuclear Power Station (PNPS) determined, based on information received from the Commonwealth of Massachusetts, that there may be a potential loss of offsite response capabilities due to ongoing severe natural hazard conditions (i.e., major winter storm) along the coast of Massachusetts. According to information received by PNPS, towns within the 10 Mile EP Radius could be hampered in implementing some protective actions specified in the emergency plan in the unlikely event an emergency were to occur. There is no condition at the Station that would warrant implementation of any emergency plan at this time. PNPS continues to operate safely and is monitoring the weather conditions closely. The Station maintains emergency assessment, response, and communication capability. This report is being made conservatively in accordance with 10 CFR 50.72(b)(3)(xiii) which is any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability. As stated previously, the Station maintains emergency assessment, response, and communication capability. The licensee notified the NRC Resident Inspector.
ENS 531987 February 2018 15:04:00DresdenNRC Region 3GE-3At approximately 1040 CST, seven (7) Dresden Nuclear Power Station Offsite Emergency Notification sirens (i.e., Siren Nos. DR1, DR4, DR5, DR6, DR9, DR10, and DR11) were inadvertently activated. The Kendall County, IL Emergency Management Agency notified the Exelon Generation Company, LLC. Emergency Response Organization that at 1040 CST, a contract individual inadvertently cut a wire that resulted in the actuation of these seven sirens for three minutes. The contract organization personnel are addressing the issue with the sirens. The Kendall and Will County Emergency Management Agency contacted Exelon Generation Company regarding this event. This notification is being made in accordance with 10 CFR 50.72(b)(2)(xi) as an event where other government agencies were notified. The NRC Resident Inspector has been informed of this notification. The sirens are operable.
ENS 5318931 January 2018 18:19:00Quad CitiesNRC Region 3GE-3At 1310 hours (CST) on January 31, 2018, the Unit 2B fuel pool radiation monitor spiked high due to an invalid actuation which caused the U1 and U2 reactor building ventilation system to isolate, B train standby gas treatment system (SBGTS) started, and the control room ventilation system also isolated as designed. Secondary containment vacuum was lost for approximately one minute, and then subsequently returned to an acceptable level in accordance with Technical Specification 3.6.4.1, 'Secondary Containment.' As a result of this transient, secondary containment was inoperable for approximately one minute. No emergency conditions were determined to exist. Troubleshooting of the radiation monitor spike is underway. Given the temporary loss of secondary containment vacuum, this event is reportable under 10CFR50.72(b)(3)(v)(C) as an event or condition that could have prevented the fulfillment of a safety function. The NRC Resident Inspector has been notified.
ENS 531474 January 2018 17:57:00PilgrimNRC Region 1GE-3On January 4, 2018, at 1410 hours EST, with the reactor at approximately 100 percent power and steady state conditions, the winter storm across the Northeast caused the loss of offsite 345 kV Line 342. Reactor power was reduced to approximately 81 percent and a procedurally required manual reactor scram was initiated. All control rods fully inserted. As a result of the reactor scram, indicated reactor water level decreased, as expected, to less than +12 inches resulting in automatic actuation of the Primary Containment Isolation Systems for Group II - Primary Containment Isolation and Reactor Building Isolation System, and Group VI - Reactor Water Cleanup System. Reactor Water Level was restored to the normal operating band. The Primary Containment Isolation Systems have been reset. The Reactor Protection System signal has been reset. Following the reactor scram, the non-safety related Control Rod Drive Pump "B" tripped on low suction pressure. Control Rod Drive Pump "A" was placed in service. All other systems operated as expected, in accordance with design. This event is reportable per the requirements of Title 10, Code of Federal Regulations (CFR) 50.72 (b)(2)(iv)(B) - "RPS Actuation" and 10 CFR 50.72 (b)(3)(iv)(A) - "Specified System Actuation. This event had no impact on the health and/or safety of the public. The NRC Resident Inspector has been notified. The main steam isolation valves are open with decay heat being removed via steam to the main condenser. Offsite power is still available from 345kV line 355. As a contingency, emergency diesel generators are running and powering safety busses per licensee procedure. The licensee notified the Commonwealth of Massachusetts. The licensee will be notifying the town of Plymouth as part of their local notifications. The licensee will be issuing a press release.
ENS 5308923 November 2017 02:54:00Quad CitiesNRC Region 3GE-3

On November 22, 2017, at 2043 (CST), Unit I MCC (Motor Control Center) 18/19-5 overvoltage relay target was found actuated and would not reset. MCC 18/19-5 was powered from the normal feed, Bus 19. Bus 19 voltages were verified to be normal. The overvoltage relay actuation would result in MCC 18/19-5 being de-energized in the event of a DBA LOCA (Design Basis Accident Loss of Coolant Accident) in which the 1/2 Emergency Diesel Generator fails to energize Bus 18, therefore rendering both divisions of the Low Pressure Cooling Injection (LPCI) mode of Residual Heat Removal (RHR) system inoperable. Technical Specification 3.5.1 Condition E was entered, requiring restoration of LPCI in 72 hours. The overvoltage target was subsequently able to be reset at 2114 (CST), restoring the LPCI function of RHR. Technical Specification 3.5.1 Condition E was exited at that time. This event is reportable under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function. The licensee notified the NRC Resident Inspector.

  • * * RETRACTION FROM RONALD SNOOK TO STEVEN VITTO ON 01/11/18 AT 1913 EST * * *

The purpose of this notification today (01/11/18) is to retract the ENS Report made on November 23, 2017 at 0248 hours EST (ENS Report #53089). Upon further review, it was determined that the Unit 1 MCC 18/19-5 overvoltage relay target that was found actuated and would initially not reset was caused only by intermittent degraded DC control power. During this event, MCC 18/19-5 remained powered from the normal feed Bus 19, and Bus 19 voltages were verified to be normal. It was further determined from plant drawings that under this condition the degraded DC control power to the Unit 1 MCC 18/19-5 overvoltage relay has no impact to the Technical Specification 3.5.1 required capability to auto transfer power from the normal Bus 19 to the alternate Bus 18 should Bus 19 lose power such as during a DBA LOCA. This overvoltage relay was installed in the early 1990's only to support enhanced reliability of the power supply to the LPCI injection valves, and its actuation due to degraded DC control power would not impact the ability to auto transfer to alternate Bus 18. Therefore, both divisions of the Low Pressure Cooling Injection (LPCI) mode of Residual Heat Removal (RHR) system would have remained fully operable under the as-found relay condition, and Technical Specification 3.5.1 Condition E was not required to be entered. On December 6, 2017, it was determined that a loose fuse clip terminal had caused the DC control power to the overvoltage relay to become degraded which in turn caused the relay target and its reset to become erratic. This fuse clip terminal was repaired on December 6, 2017. Based on the subsequent reviews of this event, the LPCI system was not required to be declared inoperable in accordance with Technical Specifications 3.5.1 during the period of the MCC 18/19-5 overvoltage relay actuation (i.e., 31 minutes on 11/22/17), and hence was not required to be reported under 10CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function. Therefore, based on this information, ENS Report #53089 is being retracted. The NRC Resident Inspector has been notified. R3DO(Jeffers) has been notified.

ENS 530597 November 2017 22:09:00Quad CitiesNRC Region 3GE-3On November 7, 2017 at 1810 (CST), Unit 1 High Pressure Coolant Injection (HPCI), was manually isolated following failure of the remote turbine trip pushbutton to function. Unit 1 HPCI Operability Testing was in progress to the point of securing the HPCI turbine with the remote manual pushbutton. The pushbutton failed to trip the turbine resulting in operator action to lower the flow controller setpoint and isolating the HPCI steam line. HPCI remains isolated and is Inoperable pending resolution of the Turbine Trip circuitry. This event is being reported as a condition that could have prevented fulfillment of a safety function in accordance with 10CFR50.72(b)(3)(v)(D). The HPCI system is a single train system and the loss of HPCI could impact the plant ability to mitigate the consequences of an accident. The Reactor Core Isolation Cooling (RCIC) system was confirmed operable. The NRC Senior Resident Inspector has been notified.
ENS 530481 November 2017 16:33:00DresdenNRC Region 3GE-3On November 1, 2017 at 1225 CDT, both the 2-220-58A Feed Water Inboard Check Valve and the 2-220-62A Feed Water Outboard Check Valve failed Local Leak Rate Testing (LLRT) acceptance criteria due to excessive leakage. These valves are considered primary containment isolation valves, and as such, are required to ensure that an adequate primary containment boundary is maintained. Technical Specification (TS) 5.5.12, 'Primary Containment Leakage Rate Testing Program,' establishes limits for Primary Containment leakage. Based upon the results of the LLRT, Dresden, Unit 2, may not have met the limits for primary containment leakage during the last operating cycle as specified in TS 5.5.12.C. Dresden Unit 2 is currently in Mode 5 for a refueling outage and per Dresden TS 3.6.1.1, 'Primary Containment,' Primary Containment is not required in the current mode of operation (i.e., Mode 5). However, in accordance with 10 CFR 50.72(b)(3)(ii)(A), this event is reportable as a condition that resulted in a principal safety barrier being seriously degraded. The NRC Resident Inspector has been notified.
ENS 5304130 October 2017 10:38:00PilgrimNRC Region 1GE-3There was a loss of power from the local grid which did not affect the power block. The support buildings lost power and a UPS failed which affects computers, switching, and telephones. This includes a loss of the Emergency Response Data System (ERDS). The Joint Information Center and Emergency Operations Facility were not affected. Though this is a major loss of communications ability, alternate communications methods are available. The licensee notified the NRC Resident Inspector.
ENS 5298421 September 2017 21:07:00Quad CitiesNRC Region 3GE-3On September 21, 2017 at 1730 (CDT) the Control Room Emergency Ventilation Air Condition (CREV AC) system was declared inoperable due a refrigerant leak from the air conditioning compressor. As a result, Technical Specification 3.7.5 Condition A was entered for Units One and Two. The CREV AC system maintains a habitable control room environment and ensures the operability of components in the control room emergency zone during accident conditions. This notification is being made in accordance with 10CFR50.72(b)(3)(v)(D) because the CREV system is a single train system. The loss of CREV AC could impact the plant's ability to mitigate the consequences of an accident. The NRC Resident Inspector has been notified.
ENS 5296412 September 2017 14:20:00DresdenNRC Region 3GE-3On September 12, 2017 at 1131 CDT, both Unit 3 Standby Liquid Control system (SLC) subsystems were declared inoperable for a through wall leak on the common discharge piping. With both subsystems inoperable, the SLC system was unable to fulfill its safety function. This event is reportable under 10 CFR 50.72(b)(3)(v)(A) for an event or condition that could have prevented the fulfillment of a safety function of a system that is needed to shut down the reactor and maintain it in a safe shutdown condition and under 10 CFR 50.72(b)(3)(v)(D) for a system that was unavailable for accident mitigation. The NRC Resident Inspector has been notified. With both trains of SLC inoperable, the licensee entered an 8-hr. action statement to restore at least one train to operability. If unable to do so, then the plant will enter a 12-hr. shutdown action statement.
ENS 529558 September 2017 16:45:00Quad CitiesNRC Region 3GE-3

On September 8, 2017 at 1130 hours CDT, Unit Two High Pressure Coolant Injection (HPCI) Minimum Flow Valve MO 2-2301-14 flow indicating switch (FIS 2-2354) failed to meet the Technical Specification Allowable Value during calibration testing. Technical Specification Table 3.3.5.1-1 Allowable Value (3.f) requires greater than or equal to 634 gpm (3.14 inches water column as required by procedure). HPCI was subsequently declared inoperable. This event is being reported as a condition that could have prevented fulfillment of a safety function in accordance with 10CFR50.72(b)(3)(v)(D). The HPCI system is a single train system and the loss of HPCI could impact the plant's ability to mitigate the consequences of an accident. The Reactor Core Isolation Cooling (RCIC) system was confirmed operable. Note: On September 8, 2017 at 1140 hours CDT, the HPCI Minimum Flow Valve MO 2-2301-14 flow indicating switch (FIS 2- 2354) was successfully recalibrated and HPCI was returned to Operable status. The NRC Senior Resident Inspector has been notified.

  • * * RETRACTION AT 1216 EDT ON 10/19/17 FROM RYAN DECKER TO DONG PARK * * *

The purpose of this notification today (10/19/17) is to retract the ENS Report made on September 8, 2017 at 1545 hours CDT (ENS Report #52955). Upon further investigation, it was determined that a surveillance procedure contained an overly restrictive statement that directed operators to immediately declare the High Pressure Coolant Injection (HPCI) system inoperable when the HPCI Minimum Flow Valve MO 2-2301-14 flow indicating switch (FIS 2-2354) fails. This statement was in conflict with existing Technical Specification (TS) 3.3.5.1, Condition E, that allows seven days to restore the HPCI FIS (instrument channel only) to an operable status prior to entry into TS 3.3.5.1, Condition H, which requires declaring HPCI inoperable immediately. Hence, during the period of FIS inoperability (i.e., 10 minutes), the HPCI system was not required to be declared inoperable in accordance with Technical Specifications. Therefore, based on this information, ENS Report # 52955 is being retracted. Note: On September 8, 2017 at 1140 hours CDT, the HPCI Minimum Flow Valve MO 2-2301-14 flow indicating switch (FIS 2-2354) was successfully recalibrated and HPCI was returned to Operable status. The NRC Resident Inspector has been notified. Notified R3DO (Daley).

ENS 5282022 June 2017 20:33:00PilgrimNRC Region 1GE-3On June 20, 2017, at 1444 hours (EDT), with the reactor at 100% core thermal power and steady state conditions, plant personnel identified that both doors in one of the secondary containment airlocks (Door #58 and Door #85) were open briefly as part of normal passage of personnel. The Technical Specification definition of SECONDARY CONTAINMENT INTEGRITY states 'At least one door in each access opening is closed.' Actions were taken to immediately close both doors and restore operability of secondary containment. PNPS (Pilgrim Nuclear Power Station) is providing an 8-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(v)(C), an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. The NRC Resident Inspector has been notified. The licensee notified the Commonwealth of Massachusetts.
ENS 5281420 June 2017 08:18:00MonticelloNRC Region 3GE-3At 2353 CDT on 6/19/2017, while performing the High Pressure Coolant Injection (HPCI) quarterly surveillance following planned maintenance, the HPCI turbine did not start as expected due to the HPCI turbine stop valve failing to open. This issue is being reported under 10 CFR 50.72(b)(3)(v)(D) as a condition that could have prevented the fulfillment of a safety function at the time of discovery. Investigation into the failure of the HPCI system to start is in progress. The unit remains at 100% power. The health and safety of the public was not affected. The NRC Resident Inspector has been notified.
ENS 527811 June 2017 23:41:00MonticelloNRC Region 3GE-3Planned maintenance to restore normal power to Plant Computer Systems resulted in an unexpected loss of all Meteorological (MET) Tower Data (at 1645 CDT). As a result, this represents a Loss of Emergency Assessment Capability and is reportable under 10CFR 50.72 (b)(3)(xiii). The isolation was restored and MET Tower Data was restored at 1845. The health and safety of the public was not affected as the plant is operating in a normal condition with no severe weather or storms in the area. Additionally meteorological data was available from the National Weather Service should this data had been necessary. The NRC Resident Inspector has been notified." The licensee will be notifying the State of Minnesota.
ENS 5275816 May 2017 00:27:00Quad CitiesNRC Region 3GE-3On May 15, 2017 at 1918 hours (CDT), Unit Two High Pressure Coolant Injection (HPCI) Minimum Flow Valve MO 2-2301-14 failed to open as required by procedure and HPCI was declared inoperable. When the HPCI Turbine was tripped, the Minimum Flow Valve did not open when system flow reduced to the low flow setpoint. This event is being reported as a condition that could have prevented fulfillment of a safety function in accordance with 10CFR50.72(b)(3)(v)(D). The HPCI system is a single train system and the loss of HPCI could impact the plant's ability to mitigate the consequences of an accident. In accordance with Technical Specification 3.5.1 Condition G, the Reactor Core Isolation Cooling (RCIC) system was confirmed operable. This places the plant in a 14-day LCO action statement. The licensee has notified the NRC Resident Inspector.
ENS 5274911 May 2017 18:11:00MonticelloNRC Region 3GE-3A can of alcohol (16.9 ounce foreign beer) was discovered unopened in an administration building refrigerator. Site security took possession of the can of alcohol. The owner of the can of alcohol is unknown. This licensee is making this 24 hour notification in accordance with 10CFR26.719(b)(1). The licensee notified the NRC Resident Inspector.
ENS 5274410 May 2017 21:40:00PilgrimNRC Region 1GE-3On Wednesday May 10, 2017, at 1411 EDT, with the reactor at 0 percent core thermal power (CTP), Pilgrim Nuclear Power Station (PNPS) was in a Refueling Outage, performing a review of Local Leak Rate Testing results, when it was concluded that PNPS had exceeded its Title 10 Code of Federal Regulations Part 50, Appendix J, Option B, Type B and C Local Leak Rate Test (LLRT) leakage criteria. Previously, on April 22, 2017, when PNPS was performing LLRT of the High Pressure Coolant Injection (HPCI) steam exhaust line check valves, both valves failed to meet their LLRT acceptance criteria specified in plant procedures. Neither of the check valves seated acceptably. Based on the ongoing evaluation of these test exceedances, it was concluded that these test results cause the plant to exceed the overall as-found minimum path Appendix J acceptance criteria of 0.6 La (126.3 SLM (Standard Liters per Minute)). Further investigation is ongoing. This event has no impact on the health and safety of the public. The licensee has notified the NRC Senior Resident Inspector. This notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(A), any event or condition that resulted in the condition of the nuclear power plant, including its principle safety barriers, being seriously degraded. The licensee will notify the Commonwealth of Massachusetts Emergency Management Agency.
ENS 5271528 April 2017 21:21:00MonticelloNRC Region 3GE-3This report is being made pursuant to 10 CFR 50.72(b)(2)(xi), as an event where notification to other government agencies has been made. On April 28, 2017, notification to the Minnesota State Duty Office was made due to a non-compliance with release of wastewater requirements in the Monticello Nuclear Generating Plant's National Pollutant Discharge Elimination System permit. There were no consequences to the health and safety of the public. The licensee notified the NRC Resident Inspector.
ENS 5268215 April 2017 13:03:00MonticelloNRC Region 3GE-3During shutdown activities with the reactor subcritical, actions were being taken to remove 11 Reactor Feed Pump from service in support of a scheduled refueling outage. Reactor Water Level on Safeguards level instrumentation dropped below +9 inches, which resulted in a valid Reactor Protection System (RPS) Scram signal and Partial Group 2 Primary Containment Isolation System (PCIS) signal. All systems functioned as required. Reactor Water Level on Safeguards instrumentation was restored to greater than +9 inches immediately. RPS and PCIS logic was reset. There was no impact to the health and safety of the public as a result of this event. This actuation of these systems is being reported per 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of any of the systems listed in 10 CFR 50.72(b)(3)(iv)(B). The NRC Resident Inspector has been notified.
ENS 5265531 March 2017 19:14:00PilgrimNRC Region 1GE-3On March 31, 2017 at 1155 hours (EDT), with the reactor at 97% core thermal power and steady state conditions, operators inadvertently caused water level to rise in the Pressure Suppression Pool (TORUS). Pilgrim Nuclear Power Station (PNPS) was restoring normal system valve line-ups after performing flushing of the suction piping of the Core Spray system in accordance with station procedures. During the process of restoring the appropriate valve line-ups, water was inadvertently transferred to the TORUS from the Condensate Storage Tank. The cause of the event is understood. The Technical Specification (TS) Limiting Condition for Operation (LCO) Action Statement (AS) 3.7.A.5 was entered. The LCO AS was exited at 1540 when TORUS water level was restored to the limits specified in LCO's 3.7.A.1.b and 3.7.A.1.m. Because the TORUS was declared inoperable, PNPS is providing an 8-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(v)(D), an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. This was a case of the water level in the TORUS being above the TS limit. The TORUS was potentially available to provide cooling to the reactor if required. The NRC Resident Inspector has been notified. The licensee notified the Commonwealth of Massachusetts and Plymouth County.
ENS 5264327 March 2017 21:54:00PilgrimNRC Region 1GE-3On March 27, 2017, at 1825 hours EDT, with the reactor at 100 percent core thermal power and steady state conditions, technicians inadvertently caused a High Pressure Coolant Injection (HPCI) System isolation, by testing the incorrect temperature switches in the TIP (Traversing In-core Probe) room. Pilgrim Nuclear Power Station (PNPS) was performing testing on the temperature switches for Reactor Core Isolation Cooling (RCIC), but the HPCI temperature switches were inadvertently actuated causing HPCI to isolate. The Limiting Condition for Operation (LCO) Action Statement 3.5.c.2 has been entered and the planned testing has been secured pending further investigation. PNPS is providing an 8-hour non-emergency notification that the HPCI System was declared inoperable in accordance with 10 CFR 50.72(b)(3)(v)(D), an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. HPCI was returned to Operable within 40 minutes. The licensee notified the NRC Resident Inspector and the Commonwealth of Massachusetts.
ENS 5258228 February 2017 21:34:00DresdenNRC Region 3GE-3

At 1825 (CST) on 02/28/2017, Dresden Station received unexpected alarm 923-5 C-1, RX BLDG DP LO (Reactor Building Differential Pressure Low). Reactor Building differential pressure was observed to briefly lose vacuum and return to a normal reading of 0.6 inches vacuum water gauge. At the time of the transient, Grundy County was under a Severe Weather Warning and gusts of wind were being monitored from the Main Control Room up to approximately 57 mph. The Reactor Building differential pressure returned to (greater than or equal to) 0.25 inches vacuum water gauge at 18:25 after 18 seconds with no operator action. Operators observed differential pressure reading to lose vacuum, below 0 inches vacuum water gauge, for approximately 3 seconds. This condition represents a failure to meet Surveillance Requirement 3.6.4.1.1. As a result, entry into Technical Specifications 3.6.4.1 condition A was made due to Secondary Containment being inoperable. This event is being reported in accordance with 10CFR50.72(b)(3)(v)(C) as a condition that could have prevented the fulfillment of a safety function. An issue report has been initiated and a 60-day Licensee Event Report will be submitted in accordance with 10CFR50.73(a)(2)(v)(C). The NRC Resident Inspector has been notified.

  • * * RETRACTION ON 4/14/17 AT 1429 EDT FROM BOBBY SHORT TO DONG PARK * * *

The purpose of this notification is to retract ENS notification 52582 made on 2/28/17 for Dresden Nuclear Power Station. The previous notification reported a potential loss of Reactor Building differential pressure due to high wind conditions and associated entry into Technical Specification 3.6.4.1 Condition A for failure to meet Surveillance Requirement 3.6.4.1.1 to maintain differential pressure above 0.25 inches vacuum water gauge. After further evaluation, it has been determined that the high winds caused a momentary low pressure pocket on the leeward side of the Reactor Building causing the differential pressure reading seen in the Main Control Room, but it did not challenge Reactor Building differential pressure or Secondary Containment. Reactor Building differential pressure indication utilizes four transmitters, one on each wall of the Reactor Building, and the most conservative reading is transmitted to the indicator in the Main Control Room. Wind conditions impacting a single transmitter would result in indication of low Reactor Building differential pressure in the Main Control Room. Procedures direct action to obtain local readings from all four Reactor Building differential pressure transmitters. After the low indication in the Main Control Room, Equipment Operators were dispatched to obtain local indication and all four transmitters were found to be indicating 0.6 inches vacuum water gauge. This was a short duration transient with no indications of an equipment failure that could impact Secondary Containment. The entire transient occurred within an 18 second window where differential pressure indication began at 0.6 inches vacuum water gauge, dropped to below 0 inches vacuum water gauge, and subsequently restored to 0.6 inches vacuum water gauge with no operator intervention. Furthermore, a significant change in Reactor Building differential pressure would impact readings on Drywell pressure because the Reactor Building pressure is used as a reference leg. Trends of Drywell pressure during the event indicated no adverse conditions implying that Reactor Building differential pressure was stable. Thus, it has been concluded that this was an indication issue and at no point during the transient would Secondary Containment have been unable to perform its safety function. Therefore, this event does not meet the criteria of 10 CFR 50.72(b)(3)(v)(C) as a condition that could have prevented the fulfillment of a safety function, and the ENS notification is being retracted. There is no longer a requirement for an associated 60-day Licensee Event Report in accordance with 10 CFR 50.73(a)(2)(v)(C). The NRC Resident Inspector has been notified. Notified R3DO (Jeffers).

ENS 525428 February 2017 17:06:00DresdenNRC Region 3GE-3

At 0851 CST on Wednesday, February 8th, 2017, the Dresden Nuclear Power Station (DNPS) Technical Support Center (TSC) Emergency Ventilation System was emergently declared inoperable due to a failure of the outside air damper to reposition. This resulted in the inability for the TSC ventilation to maintain the required air flow to support habitability during emergency conditions. Actions are being taken to repair damper to restore functionality of the TSC ventilation system. In the interim, station procedures provide guidance to relocate the TSC to an alternate facility. This event is being reported under 10 CFR 72(b)(3)(xiii), Any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability (e.g., significant portion of control room indication, Emergency Notification System, or offsite notification system). The NRC Resident Inspector has been notified.

  • * * UPDATE PROVIDED BY RYAN CHAMBERLAIN TO JEFF ROTTON AT 0418 EST ON 02/10/2017 * * *

At 0108 CST on February 10, 2017, Dresden TSC ventilation has been restored and is now functional. The NRC Resident Inspector has been notified. Notified R3DO (Kunowski).