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 Entered dateSiteRegionReactor typeEvent description
ENS 5401220 April 2019 09:54:00Duane ArnoldNRC Region 3At 0507 (CDT on April 20, 2019), the DAEC (Duane Arnold Energy Center) experienced a trip of both reactor feed pumps. Operators inserted a manual scram. All control rods inserted, as required. As a result of the feed pump trips and scram, HPCI and RCIC automatically injected. Also, containment isolations occurred, as expected for this event. All systems responded as designed. Operators are currently taking the unit to cold shutdown conditions. Vessel level is being controlled by RCIC with Condensate System available. Pressure is being controlled using Main Steam Line drains and the Main Condenser is available. Normal electrical lineup remains. The cause of the reactor feed pumps tripping is believed to be an instrument air leak to flow control valves, causing loss of suction to both feed pumps. The licensee notified the NRC Resident Inspector.
ENS 5367619 October 2018 21:44:00Duane ArnoldNRC Region 3At 1725 CDT, a Feedwater Regulating valve failed closed, resulting in a reactor level transient, which initiated a reactor trip, Primary Containment Isolation System signals to valves in Groups 2, 3, and 4 and initiation of High Pressure Coolant Injection and Reactor Core Isolation Cooling. All control rods inserted and level has been restored to normal. The cause of the feedwater valve failure is under investigation. All other systems responded as expected. This report is being made under 10 CFR 50.72 (b)(2)(iv)(B), (b)(3)(iv)(A) and (b)(2)(iv)(A). The Senior Resident Inspector has been informed. Decay heat is being removed via the main condenser and reactor vessel water level is being maintained by the condensate and feedwater systems.
ENS 5361924 September 2018 14:06:00Duane ArnoldNRC Region 3On September 22, 2018, at approximately 0050 (CDT), Duane Arnold Energy Center (DAEC) Security was contacted by a site assigned contractor that they had located what appeared to be drug paraphernalia inside the Protected Area. Local Law Enforcement was contacted and responded to DAEC. The Linn County Sheriff's office took the items into evidence for testing to determine if there was any presence of a controlled substance. On September 24, 2018, at 1013, the Linn County Sheriff's office notified DAEC that the items tested positive for the presence of a controlled substance. Therefore, this is being reported in accordance with 10 CFR 26.719. DAEC Site security is working with NextEra Corporate security regarding the investigation into this incident. The Resident Inspector has been notified."
ENS 5350011 July 2018 03:58:00Duane ArnoldNRC Region 3On July 11, 2018, as part of pre-planned maintenance, the site meteorological tower will be removed from service. The tower will be out of service for approximately 11 days. As a result, this is reportable under 10CFR 50.72 (b)(3)(xiii). During the time the data is not available from the meteorological tower; compensatory measures will be in place to obtain the data from the National Weather Service if necessary. The (NRC) Resident Inspector has been notified."
ENS 534969 July 2018 16:25:00Duane ArnoldNRC Region 3At approximately 1334 CDT on 7/9/18, both doors of a Secondary Containment Airlock were reported to be open simultaneously for a period of less than 3 seconds. The brief time that the doors were simultaneously open constituted an inoperable condition of Secondary Containment. Secondary Containment was immediately restored to operable by closing the airlock doors. Subsequently, the airlock interlock was verified to operate correctly. This event is being reported pursuant of 10 CFR 50.72(b)(3)(v)(C). The Senior NRC Resident Inspector has been notified."
ENS 5316716 January 2018 10:06:00Duane ArnoldNRC Region 3GE-4This 60-day telephone notification is being made under reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a containment isolation signal affecting more than one system. At 2230 CST on November 30, 2017, with the Duane Arnold Energy Center (DAEC) operating at 100 percent power, an invalid Group 3 isolation on the 'B' side of the Primary Containment Isolation System (PCIS) occurred. Group 3 isolation signals were generated for Primary Containment Isolation Valves for Drywell and Torus Ventilation and Purge, Containment Nitrogen Compressor Suction and Discharge, Recirculation Pump Seals, and Post Accident Sample System. This event was caused by a fault on the 1D25 Instrument AC Inverter. The fault was caused by an insufficient design clearance to ground and was corrected by increasing the clearance. All equipment responded in accordance with the plant design. Specifically, all actuations were complete and successful. There were no safety consequences or impacts on the health and safety of the public. The event was entered into DAEC's corrective action program for resolution. The NRC Resident Inspector has been notified.
ENS 528811 August 2017 17:00:00Duane ArnoldNRC Region 3GE-4

At 0934 CDT, while appropriately removed from service for pre-planned testing, the High Pressure Coolant Injection (HPCI) inboard steam isolation valve, MO-2238, valve position indication was found to be inadequate. As a result, MO-2238 was declared inoperable in accordance with Technical Specification (TS) 3.6.1.3. This resulted in a condition that caused the HPCI system to be inoperable. The cause of the inadequate valve position indication is currently being investigated. This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector has been informed.

  • * * RETRACTION ON 09/11/17 AT 1144 EDT FROM BOB MURRELL TO BETHANY CECERE * * *

The purpose of this notification is to retract a previous report made on 8/1/17 at 1700 (EDT) (EN 52881). NRC notification was initially made as a result of the High Pressure Coolant Injection (HPCI) inboard steam isolation valve, MO-2238, valve position found to be inadequate. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the condition observed on 8/1/17 for MO-2238 did not exist prior to removing the system from service for pre-planned testing, but was observed during post maintenance testing. Consequently, the failure does not meet the reporting requirements of 10 CFR 50.72 or 10 CFR 50.73. The NRC Resident Inspector has been notified. Notified the R3DO (Riemer).

ENS 5251126 January 2017 11:26:00Duane ArnoldNRC Region 3GE-4On January 25, 2017, at 1800 CST, during planned surveillance testing, the Drywell Vent Line Inboard Isolation valve, CV-4302, was found to exceed its valve leakage limits and was declared inoperable. After completion of repairs to CV-4302, post maintenance testing showed that the Drywell Vent Line Outboard Isolation valve, CV-4303, was exceeding its valve leakage limits, and therefore, was declared inoperable at 0300 CST on January 26, 2017. This resulted in a containment penetration flow path not within purge valve leakage limits and is reportable in accordance with 10 CFR 50.72(b)(3)(v)(C). Repairs were completed on CV-4303 and both containment valves were declared operable at 1007 CST on January 26, 2017. Secondary Containment was operable at all times. The NRC Resident Inspector has been informed.
ENS 5205329 June 2016 17:21:00Duane ArnoldNRC Region 3GE-4At 0940 CDT on 6/29/2016, both doors of a Secondary Containment Airlock were reported to be open simultaneously for a period of less than 5 seconds. The brief time that the doors were simultaneously open constituted an inoperable condition of Secondary Containment. Secondary Containment was immediately restored to operable by closing the airlock doors. The airlock interlock was repaired and verified to operate correctly. This event is being reported pursuant of 10 CFR 50.72(b)(3)(v)(C). The Senior Resident Inspector has been notified.
ENS 5202219 June 2016 21:38:00Duane ArnoldNRC Region 3GE-4At 1533 CDT on 06/19/2016, while performing Tech Spec Secondary Containment Airlock verification testing, both doors of a Secondary Containment Airlock were reported to be open simultaneously. The identified condition caused Secondary Containment to be considered inoperable. Upon discovery, immediate action was taken to close the doors restoring Secondary Containment. Airlock doors were under control of plant personnel throughout the event. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The licensee informed the NRC Resident Inspector.
ENS 5186312 April 2016 14:36:00Duane ArnoldNRC Region 3GE-4

On April 12, at 1235 CDT, Duane Arnold Energy Center contacted officials with the State of Iowa (Bureau of Radiological Health and Department of Natural Resources) and Linn County Public Health Department in accordance with the nuclear industry voluntary reporting criteria contained in NEI 07-07 'Industry Ground Water Protection Initiative'. The site contacted the agencies as courtesy to notify them about the identification of low levels of tritium found within the site's protected area from a potential new source. Samples were taken, and no regulatory limits were exceeded. The site team is working with industry experts on pinpointing the cause and installing an extraction well to remediate the situation. This report is being made in accordance with 10 CFR 50.72(b)(2)(xi), as a result of notification to offsite agencies.

The Licensee has notified the NRC Resident Inspectors. There is no risk to plant employees, the public or drinking water.

ENS 5169729 January 2016 17:09:00Duane ArnoldNRC Region 3GE-4

At 0920 CST on 1/29/16, while performing main generator voltage adjustments at the direction of the transmission operator, Duane Arnold Energy Center (DAEC) switchyard voltage lowered to the calculated point where offsite sources were considered inoperable. During this event, both onsite emergency diesel generators were fully operable and capable of performing their intended safety function. While no safety concerns arose, Technical Specification (TS) Limiting Condition for Operability (LCO) 3.8.1.a Condition C was entered due to two offsite electric power circuits being inoperable. Immediate actions were taken to adjust main generator voltage to restore switchyard voltage. In less than 10 minutes, both offsite circuits were declared operable and LCO 3.8.1.a Condition C was exited. This resulted in a reportable event pursuant to 10CFR50.72(b)(3)(v)(D). During the time of reduced grid voltage, no bus low-voltage alarms nor any equipment issues occurred. The cause of this event is under investigation, and there are not any current operability concerns with the offsite power circuits. The licensee has notified the NRC Resident Inspector.

  • * * RETRACTION FROM ROBERT MURRELL TO DANIEL MILLS AT 1319 EST ON 02/05/2016 * * *

The purpose of this notification is to retract a previous report made on 1/29/16 at 1709 (EST). NRC notification was initially made as a result of offsite power sources being declared inoperable due to the identification of a low voltage condition by the grid operator. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the offsite power grid conditions were above the required limit and were therefore operable. It was determined that a trip of the DAEC turbine/generator would not have led to fluctuations in voltages in the DAEC switchyard below the trip setpoints for Loss of Power. Based on this, the safety-related buses and loads were fully capable of performing their intended design basis function. The degraded voltage relays setpoint were not reached; therefore, the essential electrical buses remained connected to offsite power. Therefore, the low voltage condition does not meet the reporting requirements of 10 CFR 50.72 or 10 CFR 50.73 The Resident Inspector has been notified. Notified R3DO (Kozak).

ENS 5148420 October 2015 23:55:00Duane ArnoldNRC Region 3GE-4This report is being made under 10CFR50.72(b)(3)(iv)(A) 'any event or condition that results in a valid actuation of any system listed in paragraph (b)(3)(iv)(B) of this section' due to the automatic start of 'A' and 'B' Standby Diesel Generators. The automatic start of the Standby Diesel Generators occurred on a valid bus under-voltage condition caused by severe weather (lightning strikes) in the DAEC (Duane Arnold Energy Center) area. The Standby Diesel Generator output breakers did not close onto their respective essential buses. Essential electrical buses remained powered from off-site circuits through their normal power supply transformer, 1X3 Startup Transformer, during and after the event. The Standby Diesel Generators have been returned to the standby readiness condition. Both credited off-site power circuits were available before the event and remain available after the event. The licensee notified the NRC Resident Inspector.
ENS 5135327 August 2015 14:10:00Duane ArnoldNRC Region 3GE-4At 0752 CDT on 8/27/2015, both doors of a Secondary Containment Airlock were reported to be open simultaneously for a period of approximately five seconds. The brief time that the doors were simultaneously open constituted an inoperable condition of Secondary Containment. The airlock interlock was verified to operate correctly, and Secondary Containment has been restored to an operable status. The licensee has notified the NRC Resident Inspector.
ENS 5100623 April 2015 18:51:00Duane ArnoldNRC Region 3GE-4

At 1050 (CDT) on 4/23/2015, an equipment malfunction resulted in DAEC (Duane Arnold Energy Center) declaring the Division 1 Essential Electrical Bus inoperable. The LPCI ( Low Pressure Coolant Injection) system was inoperable but available as part of a planned evolution at the time of the malfunction. Declaring the Essential Electrical Bus inoperable caused the 'A' Core Spray System to be considered inoperable. LPCI and 'A' Core Spray being inoperable simultaneously constituted a loss of safety function. The 'B' Core Spray system remained operable and available. The equipment malfunction was resolved promptly, allowing the Division 1 Essential Electrical Bus to be returned to an operable status. The notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(D). The (NRC) Resident Inspector has been notified. The licensee entered and exited TS LCO 3.5.1 condition B.

  • * * RETRACTION FROM BOB MURRELL TO DONALD NORWOOD AT 0835 EDT ON 5/8/2015 * * *

The purpose of this notification is to retract a previous report made on 4/23/15 at 1851 EDT (EN 51006). Notification to the NRC was initially made as a result of an event or condition that could prevent the fulfillment of the safety function of Emergency Core Cooling System (ECCS) due to an equipment malfunction associated with the Division 1 Essential Electrical Bus Breaker 1A306. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the Division 1 Essential Electrical Bus was fully capable of performing its intended safety function with the malfunction on Bus Breaker 1A306. Therefore, this event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Resident Inspector has been notified. Notified R3DO (Skokowski).

ENS 5098916 April 2015 18:06:00Duane ArnoldNRC Region 3GE-4At 1320 CDT, on April 16, 2015, both doors of a Secondary Containment Airlock were reported to be open. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.4.1. Upon discovery, immediate action was taken to close the doors. The doors were open concurrently for a momentary amount of time. The action to close the door allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status. The notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified. The licensee is investigating how the electrical interlock failed to prevent this occurrence.
ENS 5094331 March 2015 18:29:00Duane ArnoldNRC Region 3GE-4The issue described in this report was addressed during the station's most recent refueling and maintenance outage in October of 2014 and no longer exists. During an inspection of Suppression Pool (torus) during the October 2014 outage, degradation of the torus coating was discovered. Some of the coating had become delaminated. NextEra Energy DAEC (Duane Arnold Energy Center) took immediate action to restore the coating to within design parameters during the refueling outage and the degraded condition no longer exists. Extensive analysis was performed to determine effect of the delaminated material. Upon completion of this investigation, NextEra Energy DAEC has determined an unanalyzed condition existed as a result of the coating degradation and is reporting the condition under 10 CFR 50.72(b)(3)(ii)(B). A root cause evaluation has been performed to determine causes and corrective actions. The NRC Resident Inspector has been notified.
ENS 5091421 March 2015 04:15:00Duane ArnoldNRC Region 3GE-4At 0030 CDT, on March 21, 2015, both doors of a Secondary Containment Airlock were opened concurrently by two separate individuals. The doors being open at the same time caused a failure to meet SR (Surveillance Requirement) 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO (Technical Specification Limiting Condition for Operation) 3.6.4.1. Upon discovery, immediate action was taken to close the doors. The doors were open concurrently for a momentary amount of time. The action to close the door allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified.
ENS 5089113 March 2015 18:59:00Duane ArnoldNRC Region 3GE-4

This condition is reported in accordance with 10 CFR 50.72(b)(3)(v). On 3/12/15, during surveillance testing on LPCI (Low Pressure Coolant Injection) Loop Select Instrumentation, a degraded component was discovered. At 1230 CDT on 3/13/15, LPCI was declared INOPERABLE in accordance with Technical Specification requirements. All remaining ECCS systems remain available and operable. The NRC Resident Inspector has been informed.

  • * * UPDATE AT 0210 EDT ON 03/14/15 FROM SCOTT AREBAUGH TO S. SANDIN * * *

At 0105 CDT on 3/14/15, the subject component has been replaced and retested with satisfactory results. LPCI INOPERABLE condition was exited at 0105 CDT and the LPCI System is OPERABLE. The licensee informed the NRC Resident Inspector. Notified R3DO (Orth).

  • * * RETRACTION AT 1737 EDT ON 04/23/15 FROM BOB MURRELL TO DONG PARK * * *

The purpose of this notification is to retract a previous report made on 3/13/15 at 1859 EDT. Notification of the event to the NRC was initially made as a result of an event where Low Pressure Coolant Injection (LPCI) was declared inoperable due to the discovery of a degraded LPCI Loop Select timing relay. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the LPCI Loop Select timing relay was tested in a configuration that affected time delay measurements. This testing configuration was revised in 2012 following a modification to the LPCI Loop Select Logic, STP 3.3.5.1-29. The inadequate testing configuration adversely affected the time delay when the test equipment was installed. A revision to STP 3.3.5.1-29 was completed to resolve the inadequate testing configuration. Subsequent bench testing, performed to mimic plant installed configuration, of the affected relay, was completed. This testing demonstrated that the relay could be tested in a manner that provided acceptable results, and it has been concluded that the relay would have performed its required safety function up to when it was tested on 3/13/15. Therefore, this event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Resident Inspector has been notified. Notified R3DO (Valos).

ENS 5074319 January 2015 02:30:00Duane ArnoldNRC Region 3GE-4

At 2131 CST on January 18, the Duane Arnold Energy Center (DAEC) Technical Support Center (TSC) Normal Power was lost when a single phase to the T4 '36KV-12.5KV DAEC SITE TRANSFORMER' was lost due to a blown primary side fuse. Automatic power transfer occurred to maintain power to the TSC from the TSC Emergency Diesel Generator (EDG) which automatically started. The TSC remained functional throughout the incident. This notification is being made pursuant to 10 CFR 50.72(b)(3)(xiii) due to the loss of an emergency assessment capability. An update will be provided once the normal power supply has been restored. The licensee notified the NRC Resident Inspector.

  • * * UPDATE FROM DOUG PETERSON TO VINCE KLCO AT 1419 EST AT 1/21/15 * * *

Normal power restored to the TSC. The licensee notified the NRC Resident Inspector. Notified the R3DO (Duncan).

ENS 5056023 October 2014 09:48:00Duane ArnoldNRC Region 3GE-4

At 0107 CDT on October 23rd, 2014, both doors in one of the Secondary Containment airlocks were momentarily open concurrently. This occurred during vessel drain down following refueling activities, an Operation with the Potential to Drain the Reactor Vessel (OPDRV), which required Secondary Containment to be operable. The doors being open at the same time resulted in the momentary inoperability of Secondary Containment. One of the doors was immediately closed, and Secondary Containment was restored to an operable status. The station (Duane Arnold) has now completed the OPDRV associated with vessel drain down, and Secondary Containment is no longer required to be operable. The Resident Inspector has been notified.

  • * * RETRACTION FROM BOB MURRELL TO JOHN SHOEMAKER AT 1232 EST ON 12/17/14 * * *

The purpose of this notification is to retract a previous report made on 10/23/2014, at 0948 (EDT) (EN 50560). Notification of the event to the NRC was initially made as a result of an event where both doors in one of the Secondary Containment airlocks were momentarily open concurrently. This occurred during vessel drain down following refueling activities, an Operation with the Potential to Drain the Reactor Vessel (OPDRV), which required Secondary Containment to be operable. The doors being open at the same time resulted in the momentary inoperability of Secondary Containment. One of the doors was immediately closed, and Secondary Containment was restored to an operable status. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the doors in question were not mechanically degraded such that they were incapable of being closed. A momentary condition of having both secondary containment airlock doors open for a matter of seconds is not an event or condition that could have prevented the fulfillment of a safety. Furthermore, the conduct of OPDRVs during a momentary opening of both secondary containment doors that is immediately rectified does not constitute a condition prohibited by TS. Therefore, this event is not considered a Safety System Functional Failure or a Condition Prohibited by TS and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Senior Resident Inspector has been notified. Notified the R3DO (McCraw). .

ENS 5037515 August 2014 18:02:00Duane ArnoldNRC Region 3GE-4

On 8/15/2014 at 1218 CDT, the 'B' Standby Gas Treatment (SBGT) System was undergoing its monthly surveillance testing. With the 'B' fan running, as part of the surveillance, the 'A' Standby Gas Treatment Mode Select Switch was taken to Manual. This renders the 'A' SBGT subsystem inoperable. Almost simultaneously the 'B' fan Flow Indicating Controller went blank and flashed an error message although indicated flow through the 'B' train remained at 4073 SCFM. Based on the indication seen on 'B' controller, regardless of flow, the 'B' SBGT subsystem was also declared inoperable. In accordance with the surveillance the 'A' SBGT mode switch was placed back in the AUTO position on 8/15/2014 at 1220 CDT, restoring that train to operability. The 'B' SBGT was still considered inoperable based on its flow indicating controller being blank and flashing an error message. For a period of two minutes both SBGT subsystems were considered inoperable which is a condition that could have prevented the fulfillment of the safety function of SBGT system to control the release of radioactive material. This is considered a 8-hour reportable event per 50.72(b)(3)(v)(C) 'Any event or condition that at the time discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.' During the 2 minutes that 'A' SBGT was in Manual, the 'B' SBGT train maintained 4073 scfm train flow which is at the required flow rate per STP 3.6.4.3-01B. In addition, the 'A' train could have been initiated manually at any time during that 2 minutes by the operator who was stationed at the panel performing the surveillance. The licensee notified the NRC Resident Inspector.

  • * * RETRACTION PROVIDED BY BOB MURRELL TO DANIEL MILLS AT 0835 EDT ON 09/16/2014 * * *

The purpose of this notification is to retract a previous report made on 08/15/2014 at 1802 (EDT) (EN 50375). Notification of the event to the NRC was initially made as a result of declaring both trains of the Standby Gas Treatment (SBGT) System inoperable. Specifically, during performance of planned surveillance testing required by Technical Specification (TS) Surveillance Requirement (SR) 3.6.4.3.2, with the 'B' train of SBGT running as part of the testing, the 'A' SBGT train's mode switch was taken to manual. This action renders the 'A' train inoperable. Simultaneously with this action, the 'B' SBGT Flow Indicator Controller went blank and flashed an error message. This resulted in the 'B' train being declared inoperable. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that TS SR 3.6.4.3.2 contains a note that states, 'When a SBGT subsystem is placed in an inoperable status solely for the performance of VFTP testing required by this Surveillance on the other subsystem, entry into associated Conditions and Required Actions may be delayed for up to 1 hour.' The 'A' SBGT train mode switch was in manual for approximately 2 minutes; therefore, entry into the associated conditions and actions was not required. Therefore, this event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Senior Resident Inspector has been notified. Notified R3DO (Dickson)

ENS 5024630 June 2014 23:54:00Duane ArnoldNRC Region 3GE-4This report is being made under 10CFR50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section' due to an auto start of 'A' and 'B' Standby Diesel Generators. At 1913 CDT, a grid disturbance during a local thunderstorm caused a valid bus undervoltage condition that resulted in the auto start of both the 'A' and 'B' Standby Diesel Generators. The 'A' and 'B' Standby Diesel Generator supply breakers did not close onto their respective buses as they remained powered by their normal power supply, the 1X003 Startup Transformer, during and after the event. NextEra Duane Arnold personnel inspections revealed no issues with breakers in the switchyard. ITC (Iowa Transmission Company) reported a fault on a 161 Kv line in the NextEra Duane Arnold vicinity. Offsite power remained operable during and following the event. As designed the 'A' and 'B' Emergency Service Water systems auto started when the diesel generators auto started. The Emergency Service Water systems and both Standby Diesel Generators have been returned to standby/readiness condition. All ECCS (Emergency Core Cooling System) systems were available before the event and have remained available following the event. The licensee notified the NRC Resident Inspector.
ENS 5024330 June 2014 17:55:00Duane ArnoldNRC Region 3GE-4This is a one hour report for the discovery of a condition that briefly met the emergency action level (EAL) for an Unusual Event but did not warrant declaration of an emergency classification. A detailed review of the conditions that existed during a thunderstorm that took place today revealed that the backup 50 meter wind speed briefly indicated 95.5 mph, which exceeds the HU 1.3 criteria of 95 mph. The primary 50 meter wind speed indicator did not exceed 89 mph. Operators in the control room did not observe wind speed exceed 80 mph on SPDS. This event is a one hour report based on the guidance in NUREG-1022 for a condition that met an emergency plan EAL and the basis for the emergency classification no longer existed at the time of discovery." The NRC Resident Inspector has been informed.
ENS 5015330 May 2014 14:43:00Duane ArnoldNRC Region 3GE-4At 0759, on May 30, 2014, both doors in one of the Secondary Containment Airlocks were open concurrently. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered INOPERABLE per TS LCO 3.6.1.4. Upon discovery, immediate action was taken to close the doors. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to OPERABLE status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified. The cause of this event was a misaligned door magnet.
ENS 5015430 May 2014 14:43:00Duane ArnoldNRC Region 3GE-4At 1043 CDT, during an instrument test, the High Pressure Coolant Injection (HPCI) system isolated due to an invalid signal. The isolation was on the 'A' (inboard) logic, which rendered the HPCI system INOPERABLE. The isolation was received while instrument technicians were installing a relay block during the performance of Surveillance Test Procedure 3.3.6.1-43 'HPCI Steam Line High DP Instrument Channel Functional Test.' Operations Personnel have repressurized HPCI piping, installed the relay cover, and declared HPCI System OPERABLE at 1209 (CDT). This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) due to the failure of a single train system preventing accident mitigation. The NRC Resident Inspector has been informed.
ENS 4983818 February 2014 13:18:00Duane ArnoldNRC Region 3GE-4At 0944 CST, on February 18, 2014, both doors in the Secondary Containment Airlock were opened concurrently. The doors being open at the same time caused a failure to meet SR 3.6.1.4.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.1.4. Upon discovery, immediate action was taken to close the doors. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to operable status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified.
ENS 4974721 January 2014 05:48:00Duane ArnoldNRC Region 3GE-4

On 1/20/14 at 2230 CST, an interruption in the control power to the TSC diesel generator was discovered. Investigation revealed a blown fuse supplying the TSC diesel generator control panel. The blown fuse has resulted in the TSC diesel generator starting batteries depleting. The fuse has since been replaced, and the TSC diesel generator starting batteries are currently recharging. The TSC diesel generator remains non-functional until the starting batteries are charged. This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii) due to the unplanned loss of the backup power supply to the Emergency Response Facility (ERF). The NRC Resident Inspector has been informed. An update notification will be made when the TSC diesel generator has been restored to fully functional status.

  • * * UPDATE FROM NATHAN PIEPER TO HOWIE CROUCH AT 1551 EST ON 1/23/14 * * *

At 1400 CST, the licensee restored the TSC emergency diesel generator to functional status. The NRC Resident Inspector was notified by the licensee. Notified R3DO (Valos).

ENS 4965718 December 2013 15:39:00Duane ArnoldNRC Region 3GE-4At 0830 CST on December 18, 2013, both doors in the Secondary Containment Airlock were opened concurrently. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.4.1. Upon discovery, immediate action was taken to close the doors. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status. This notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(C). The NRC Resident Inspector has been notified.
ENS 4956621 November 2013 10:38:00Duane ArnoldNRC Region 3GE-4

Following preplanned maintenance on the inoperable 'A' Standby Diesel Generator (SBDG), the operability surveillance (STP-3.8.1-04A Slow Start from Normal Air) was in progress. While securing the 'A' SBDG, the 'B' SBDG control power failure annunciator was received. The 'B' Standby Diesel Generator was declared inoperable and Technical Specification 3.8.1.B was entered for the 'B' SBDG. Additionally, Technical Specification 3.8.1.D was entered for two Standby Diesel Generators inoperable. Technical Specification 3.8.1.D allows 2 hours to restore 1 SBDG to operable. At 0343 (CST), the 'A' SBDG was restored to operable and Technical Specification 3.8.1.D was exited. This condition is reported under 50.72(b)(3)(v)(D), any event or condition 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. The NRC Resident Inspector was informed.

  • * * RETRACTION FROM BOB MURRELL TO DONALD NORWOOD AT 1348 EDT ON 8/28/2014 * * *

The purpose of this notification is to retract a previous report made on 11/21/2013 at 1038 EST (EN 49566). Notification of the event to the NRC was initially made as a result of declaring both trains of the Emergency Diesel Generator (EDG) System inoperable due to receiving the 'B' EDG control power failure annunciator while the 'A' EDG was inoperable for pre-planned maintenance. Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the 'B' EDG system was capable of performing its safety function and was fully operable, but degraded during the period that the 'A' EDG was inoperable for pre-planned maintenance. The cause of the annunciator was from an open fuse in the control power circuit that affected the annunciator system logic and did not affect the actual EDG control logic. This event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73. The NRC Senior Resident Inspector has been notified. Notified R3DO (Stone).

ENS 4955719 November 2013 08:29:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) will remove the emergency power supply to the TSC from service. The TSC would be rendered non-functional with the loss of normal power. The repair to the power supply is expected to last 1 day. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures. Maintenance will be expedited to restore the emergency power supply to service. This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii) due to the loss of an Emergency Response Facility (ERF). An update will be provided once the TSC emergency power supply has been restored to normal operation. The NRC Resident Inspector has been notified.

  • * * UPDATE FROM TERRY BRANDT TO DONG PARK AT 1653 EDT ON 11/19/13 * * *

The emergency power has been returned to service to the TSC.

 The licensee has notified the NRC Resident Inspector.

Notified R3DO (Hills).

ENS 495218 November 2013 15:25:00Duane ArnoldNRC Region 3GE-4At approximately 1104 CST on November 08, 2013, in the Owner Controlled Area, a station employee fell ill from an apparent personal medical condition. The employee was transported off site and passed away. The death was not related to activities impacting or related to the safety of the public or other on site personnel. Specifically, the individual collapsed and was promptly examined by Duane Arnold Energy Center Emergency Medical Technician(s). An ambulance evacuation was then ordered. The death was not work-related nor the result of an accident. The individual was outside of the Radiological Controlled Area and no radioactive material or contamination was involved. Duane Arnold Energy Center has not observed any heightened public or media concern as a result of the death. Since the death is apparently unrelated to Duane Arnold Energy Center industrial or radiological health and safety, no news release is planned. The individual's name has not yet been released, pending notification of next-of-kin. The Iowa Division of Occupational Safety and Health was notified of the death at 1340 CST. The licensee notified the NRC Resident Inspector.
ENS 494157 October 2013 11:44:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) will de-energize the Meteorological Data Tower. No other indications or annunciators will be unavailable during this maintenance to affect the plant's ability to assess or monitor an accident or transient in progress. National Weather Service data is expected to be available throughout the duration of the planned maintenance. A follow up notification will be provided when power to the Meteorological Data Tower has been restored. The NRC Resident Inspector has been notified.

  • * * UPDATE AT 1718 EDT ON 10/07/13 FROM TERRY BRANDT TO HUFFMAN * * *

Maintenance activities on the Meteorological Data Tower is complete and the tower has been returned to service. The licensee has notified the NRC Resident Inspector. R3DO (Skokowski) notified.

ENS 4938325 September 2013 11:08:00Duane ArnoldNRC Region 3GE-4

At 0304 (CDT), on Sept 25, 2013, the Duane Arnold Energy Center (DAEC) Technical Support Center (TSC) normal power supply was lost when the T4 '36KV-12.5KV DAEC SITE TRANSFORMER' was lost. Automatic power transfer occurred to maintain power to the TSC from the TSC Emergency Diesel Generator (EDG) which automatically started. Prior to the loss of normal power, the TSC Emergency Diesel Generator maintenance functional testing had been completed and was in standby readiness, awaiting post maintenance testing to be completed on the auto start circuit. The TSC Emergency Diesel Generator responded normally to the loss of power and energized TSC loads. The TSC remained functional throughout the incident. This notification is being made pursuant to 10 CFR 50.72(b)(3)(xiii) due to the loss of an emergency assessment capability. An update will be provided once the normal power supply has been restored. The NRC Resident Inspector has been notified.

  • * * UPDATE FROM STEVE SPEIRS TO HOWIE CROUCH AT 1844 EDT ON 11/2/13 * * *

The TSC normal power supply was returned to service at 1830 EDT on 11/2/13. The licensee will be notifying the NRC Resident Inspector. Notified R3DO (Daley).

ENS 4935719 September 2013 09:58:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) will remove the emergency power supply to the TSC from service. The TSC would be rendered non-functional with the loss of emergency power. The repair to the power supply is expected to last 2 hours. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures. Maintenance will be expedited to restore the emergency power supply to service. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the loss of an Emergency Response Facility (ERF). An update will be provided once the TSC emergency power supply has been restored to normal operation. NRC Resident Inspector has been notified.

  • * * UPDATE FROM TIM ERGER TO HOWIE CROUCH AT 1325 EDT ON 9/22/13 * * *

The TSC EDG remains unavailable due to emergent work. The licensee has notified the NRC Resident Inspector. Notified R3DO (Riemer).

  • * * UPDATE FROM MIKE STROPE TO DANIEL MILLS AT 1237 EDT ON 9/25/13 * * *

The TSC EDG has returned to functional status. The licensee notified the NRC Resident Inspector. Notified R3DO (Dickson).

ENS 4915127 June 2013 11:33:00Duane ArnoldNRC Region 3GE-4This 60-day telephone notification is being made under reporting requirements specified by 10CFR50.73(a)(2)(iv)(A) to describe an invalid actuation of a containment isolation signal affecting more than one system. At 1307 CDT on May 2, 2013, with the Duane Arnold Energy Center (DAEC) operating at 100% power, an invalid Group 3 isolation on the 'A' side of the Primary Containment Isolation System occurred. Group 3 isolation signals were generated for Primary Containment Isolation Valves for Drywell and Torus Ventilation, and Purge, Containment Nitrogen Compressor Suction and Discharge, Recirculation Pump Seals, and Post Accident Sample System. This event was caused by a human performance error that led to a blown fuse. Specifically, the fuse failed during pre-planned maintenance on a differential pressure switch when a test clip made inadvertent contact with an energized part of the switch. All equipment responded in accordance with the plant design. Specifically, all actuations were complete and successful. There were no safety consequences or impacts on the health and safety of the public. The event was entered into DAEC's corrective action program for resolution. The licensee notified the NRC Resident Inspector.
ENS 490926 June 2013 09:27:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) has removed the emergency power supply to the TSC from service as of 0900 EDT. If a loss of the normal power supply to the TSC were to occur during this period, the TSC would be rendered non-functional. The repair to the power supply is expected to last 6 hours. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures. Maintenance will be expedited to restore the emergency power supply to service. This notification is being made in accordance with 10 CFR 50.72(b)(3)(xiii) due to the loss of an Emergency Response Facility (ERF). An update will be provided once the TSC emergency power supply has been restored to normal operation. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE ON 6/6/13 AT 1614 EDT FROM STEPHEN SPEIRS TO DANIEL MILLS * * *

The TSC diesel generator has been returned to functional status. The NRC Resident Inspector has been notified R3DO (Lipa) has been notified.

ENS 4876719 February 2013 13:31:00Duane ArnoldNRC Region 3GE-4This 60-day telephone notification is being made under reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a containment isolation signal affecting more than one system. At 0354 CST on December 20, 2012, with the Duane Arnold Energy Center (DAEC) operating at 100% power, an invalid Group 3 isolation on the 'A' side of the Primary Containment Isolation System occurred. Group 3 isolation signals were generated for Primary Containment Isolation Valves for Drywell and Torus Ventilation, and Purge, Containment Nitrogen Compressor Suction and Discharge, Recirculation Pump Seals, and Post Accident Sample System. This event was caused by spurious upscale spike on the 'A' Refuel Floor Exhaust Radiation Monitor. All equipment responded in accordance with the plant design. Specifically, all actuations were complete and successful. There were no safety consequences or impacts on the health and safety of the public. The event was entered into DAEC's corrective action program for resolution. The licensee notified the NRC Resident Inspector.
ENS 486483 January 2013 15:03:00Duane ArnoldNRC Region 3GE-4

At 0930 (CST) on January 03, 2013 NextEra Energy Duane Arnold discovered that the Emergency Response Data System (ERDS) was no longer capable of transmitting plant data to the NRC. The loss of ERDS is reportable per 50.72(b)(3)(xiii). At 1151 (CST) on January 03, 2013 Information Management personnel restored ERDS to working status. The NRC Resident (Inspector) has been notified. The licensee has the cause under investigation.

  • * * UPDATE AT 2136 EST ON 01/03/13 FROM STEPHEN SPEIRS TO S. SANDIN * * *

At 1725 (CST) on January 03, 2013 NextEra Energy Duane Arnold experienced a four minute interruption of the Emergency Response Data System (ERDS). During this time, ERDS was not capable of transmitting plant data to the NRC. The loss of ERDS is reportable per 10 CFR 50.72(b)(3)(xiii). The interruption of ERDS is related to a previous problem with the system reported under EN #48648. Troubleshooting of ERDS continues to ensure long-term reliability. Additional interruptions of ERDS are possible during this troubleshooting, and a follow-up notification will be made when ERDS reliability is assured. The licensee informed the NRC Resident Inspector. Notified R3DO (Skokowski), ERDS Group and CAT Group via email.

  • * * UPDATE FROM ROB SPADING TO CHARLES TEAL ON 1/28/13 AT 1436 EST * * *

Maintenance is complete on the ERDS system. It was tested satisfactorily on 01/15/13 at 1130 CST and returned to fully functional status. The NRC Resident Inspector has been informed. Notified R3DO (Stone), ERDS Group and CAT Group via email.

ENS 4860118 December 2012 11:20:00Duane ArnoldNRC Region 3GE-4This 60-day telephone notification is being made under reporting requirements specified by 10CFR50.73(a)(2)(iv)(A) to describe an invalid actuation of a containment isolation signal affecting more than one system. At 1920 on October 20, 2012, with the Duane Arnold Energy Center (DAEC) shut down for a preplanned refueling outage, an invalid Group 3 isolation on the 'A' side of the Primary Containment Isolation System occurred. Group 3 isolation signals were generated for Primary Containment Isolation Valves for Drywell and Torus Ventilation, and Purge, Containment Nitrogen Compressor Suction and Discharge, Recirculation Pump Seals, and Post Accident Sample System. This event was caused by failed components in the power supply circuitry for the 'A' Refuel Floor Exhaust Radiation Monitor. All equipment responded in accordance with the plant design. Specifically, all actuations were complete and successful. There were no safety consequences or impacts on the health and safety of the public. The event was entered into DAEC's corrective action program for resolution. The licensee notified the NRC Resident Inspector.
ENS 4851016 November 2012 09:04:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at Duane Arnold Energy Center (DAEC) to replace a hard drive in the plant process computer will result in a loss of all SPDS indication for a duration of less than six hours. There is no planned maintenance affecting Primary Indications or Annunciators in the Control Room which would affect the plant's ability to assess or monitor an accident or transient in progress. This notification is being made pursuant to 10CFR50.72(b)(3)(xiii). The licensee will notify the NRC Resident Inspector.

  • * * UPDATE AT 1433 EST ON 11/16/12 FROM MANKIN TO HUFFMAN * * *

The planned maintenance has been completed and SPDS returned to service at 1431 EST. The licensee has notified the NRC Resident Inspector. R3DO(Kunowski) notified.

ENS 4840312 October 2012 17:02:00Duane ArnoldNRC Region 3GE-4On October 12, at 1535 CDT, Duane Arnold Energy Center made a voluntary report to the State of Iowa (Bureau of Radiological Health and Department of Natural Resources) and Linn County Public Health Department in accordance with the nuclear industry voluntary reporting criteria contained in NEI 07-07, 'Industry Ground Water Protection Initiative.' The subject of the report was a leak from the Condensate Storage Tanks' containment pit sump. The release occurred in an isolated area inside the plant property and has been terminated. Samples were taken and no regulatory limits were exceeded. During and following the leak, there was no impact to site worker or public health and safety. This report in being made in accordance with 10 CFR 50.72(b)(2)(xi), as a result of notification to offsite agencies. The Licensee has notified the NRC Resident Inspector. Total amount leaked was estimated to be less than 100 gallons.
ENS 4829611 September 2012 04:08:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) will remove the TSC (Technical Support Center) ventilation system from service. The TSC would be rendered non-functional with the loss of ventilation. The repair to the TSC ventilation is expected to last 3 days. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures. Maintenance will be expedited to restore ventilation to the TSC. This notification is being made in accordance with 10CR50.72(b)(3)(xiii) due to the loss of an Emergency Response Facility (ERF). An update will be provided once the TSC ventilation system has been restored to normal operation. The licensee notified the NRC Resident Inspector

  • * * UPDATE FROM MIKE STROPE TO CHARLES TEAL ON 9/12/12 AT 1157 EDT * * *

The TSC maintenance has been completed. The TSC has been restored to service. The NRC Resident Inspector has been informed. Notified R3DO (Kunowski).

ENS 4821421 August 2012 06:14:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) will remove the emergency power supply to the TSC from service. The TSC would be rendered non-functional with the loss of emergency power. The repair to the power supply is expected to last three days. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures. Maintenance will be expedited to restore the emergency power supply to service. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the loss of an Emergency Response Facility (ERF). An update will be provided once the TSC emergency power supply has been restored to normal operation. NRC Resident has been notified.

  • * * UPDATE FROM STEVE BREWER TO CHARLES TEAL ON 08/23/12 AT 1346 EDT * * *

Maintenance has been completed on the TSC. The TSC has been returned to service. Notified R3DO (Duncan).

ENS 4821220 August 2012 19:11:00Duane ArnoldNRC Region 3GE-4

On 8-20-2012 during scheduled surveillance testing, the Reactor Water Cleanup (RWCU) System Isolation Differential Flow - High function was discovered to be inoperable at 1520 CDT. The high differential flow signal is provided to detect a break in the RWCU system when area or differential temperature would not provide detection (i.e. cold leg break). This instrumentation provides isolation signals to both inboard and outboard isolation valves and its loss is being reported pursuant to 10CFR50.72(b)(3)(v)(C). The NRC Resident Inspector was notified.

  • * * RETRACTION AT 1513 EDT ON 9/27/2012 FROM BOB MURRELL TO MARK ABRAMOVITZ * * *

Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the RWCU Differential Flow High instrument loop was, at all times, capable of performing its TS function. Specifically an engineering analysis of the impact of the instrument as-found and as-left values on the overall instrument loop setting was performed. The analysis determined that the instrument in question was set at a value which would have isolated the RWCU Primary Containment Isolation Valves prior to reaching the Technical Specification (TS) allowable value and therefore the instrument loop remained capable at all times of performing its TS function. This event is not considered a Safety System Functional Failure or a Condition Prohibited by TS and is not reportable to the NRC as a Licensee Event Report (LER) per 10CFR50.73. The NRC Senior Resident Inspector has been notified. Notified the R3DO (Lipa).

ENS 480642 July 2012 18:50:00Duane ArnoldNRC Region 3GE-4A spurious isolation of the High Pressure Coolant Injection (HPCI) Outboard Steam Supply Valve and Outboard Torus Suction Valve occurred. Initial verifications indicate that the signal was not valid and investigations in the vicinity of the piping revealed no evidence of leaks. Troubleshooting is in progress. HPCI declared inoperable per TS 3.5.1 Condition F which allows 14 days to restore to operable status. All remaining ECCS and RCIC are operable and available. Grid stability has been verified. The licensee has notified the NRC Resident Inspector.
ENS 4770929 February 2012 18:07:00Duane ArnoldNRC Region 3GE-4On 2/29/2012 at 0905 (CST) during scheduled surveillance testing it was discovered that Secondary Containment isolation damper 1VAD017B3 would not fully isolate. 1VAD017B3 was declared inoperable per Technical Specification 3.6.4.2 Condition A and an 8 hour action statement to isolate the affected flowpath via a closed and deactivated damper was entered. While performing subsequent actions to isolate the companion isolation damper, 1VAD017A3, it was found on 2/29/2012 at 1222 (CST) that this damper also failed to fully isolate. This left both Secondary Containment isolation dampers in the same flowpath unable to isolate, and Technical Specification 3.6.4.2 Condition B was entered with a 4 hours action statement to isolate the affected flowpath. This condition is reported under 50.72(b)(3)(v)(C), any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of the structures or systems that are needed to control the release of radioactive material. Further actions to isolate the flowpath were successful and both 4 hour and 8 hour Technical Specification action statements were completed within the required time. The licensee informed the NRC Resident Inspector.
ENS 4756130 December 2011 02:34:00Duane ArnoldNRC Region 3GE-4Surveillance testing on Low Pressure Coolant Injection (LPCI) Loop Select logic yielded results requiring repairs to 3 of the 4 Recirculation Riser Differential Pressure instruments and calibration of all four. The instrument conditions were such that there was not reasonable assurance that the safety function of LPCI could be fulfilled during a design basis Loss Of Coolant Accident (LOCA). As such, this condition is reportable under 10 CFR 50.72(b)(3)(v)(D). The four instruments support the LPCI Loop Select logic by providing input that successfully identifies and directs LPCI flow to the unbroken recirculation loop so that core reflooding is accomplished in time to ensure that the fuel peak cladding temperature remains below the limits of 10CFR50.46. The instruments are arranged in a one-out-of-two-twice logic. The instruments were last calibrated September 26-29, 2011. At that time, pre-planned maintenance was performed to improve instrument reliability. Current testing indicates a repetitive issue with instrument drift. Repair and recalibration of each degraded instrument has been completed as the surveillance test has progressed such that the current status supports fulfillment of the safety function. The instrument type (Barton) is used in several safety systems, but there has been no notable degradation in other applications. The licensee has notified the NRC Resident Inspector.
ENS 4755729 December 2011 10:59:00Duane ArnoldNRC Region 3GE-4

A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) to replace power supplies in the plant process computer (Link 2) will result in a loss of some SPDS indications for a duration of less than 5 hours. No other indications or annunciators will be unavailable during this maintenance to affect the plant's ability to assess or monitor an accident of transient in progress. The licensee has notified the NRC Resident Inspector.

  • * * UPDATE FROM SCOTT AREBAUGH TO JOHN KNOKE AT 1146 EST ON 12/29/11 * * *

At 1006 CST on 12/29/11 the plant process computer (Link 2) was successfully restored and SPDS is functioning properly and returned to service. The licensee has notified the NRC Resident Inspector. Notified R3DO (Duncan).

ENS 475118 December 2011 14:33:00Duane ArnoldNRC Region 3GE-4This condition is being reported in accordance with 10CFR50.72(b)(3)(v) as a condition that could have prevented fulfillment of a safety function. On 12/02/2011 at 1311 CST, the Low Pressure Coolant Injection (LPCI) was declared inoperable when voiding was discovered in the 'B' Residual Heat Removal (RHR) inject vent line. Initial review of this condition for immediate reportability under 50.72(b)(3)(v), event or condition that could have prevented fulfillment of a safety function, concluded the condition was not reportable based on the availability of other Emergency Core Cooling Systems (ECCS). Specifically, Core Spray and HPCI were both available to perform the function of emergency core cooling. On 12/03/2011 at 1650 CST, LPCI was declared operable based on further examinations to determine extent of voiding, system filling and venting and completion of supporting engineering evaluations. Subsequent reviews determined that the reportability decision under 50.72(b)(3)(v) as a event or condition that could have prevented fulfillment of a safety function should be based on safety function at the system level, rather than at the ECCS function level. The decision to report the inoperability of LPCI under 50.72(b)(3)(v) was made at 1319 CST on 12/08/2011. The licensee has notified the NRC Resident Inspector.