Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 46943 | 9 June 2011 19:11:00 | This siren affects both Dresden and Braidwood Stations. This notification is for both sites. At approximately 1422 (CDT) on June 9, 2011, a Grundy County representative notified Exelon of an inadvertent siren activation. The Exelon representative contacted the siren contractor at 1423 (CDT) inquiring about siren activity in the shared Braidwood/Dresden Emergency Planning Zones. Upon review and polling of the system at 1444 (CDT), siren BD11 was identified in the area of concern with a communication failure. The siren contractor was immediately dispatched and arrived at the siren location at approximately 1520 (CDT). Upon arrival, the siren was not sounding and significant damage was identified, which was indicative of a direct lightning strike. The siren was declared out of service and repairs will begin on June 10th. This condition is reportable under 10CFR50.72(b)(2)(xi) - News release or notification of other governmental agency. The licensee notified the NRC Resident Inspector and Grundy County local authorities. See Braidwood Event #46942 concerning same event. |
| ENS 42481 | 6 April 2006 14:44:00 | At 10:39 AM on 4/6/06, Unit 2 HPCI was declared inoperable due to circuit breaker 16 failure on the ESS bus. Circuit breaker 16 opened as a result of temporarily shorting the power supply lead while installing a new HPCI temperature recorder. Trouble shooting is in progress as a result of the failure and restoration will follow. Since circuit breaker 16 provides ESS power to HPCI flow controller, HPCI was declared inoperable. This event is reportable under 1OCFR 5.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector. |
| ENS 42300 | 2 February 2006 01:43:00 | While performing DIS 1300-02, Unit 2 ISO COND Steam/Condensate Line High Flow Calibration, workers attempted to valve in DPIS 2-1349-8, U2 Isolation Condenser Return Line Hi Flow. While opening the low isolation valve the technician noticed a vibration in the sensing line. He proceeded to close the equalizer and open the high isolation. As he opened the high side isolation the DPIS indication started to ramp high. As the indication ramped above about 9 inches the technician closed the high side isolation valve. The Isolation Condenser has been isolated to comply with Technical Specification entered TS 3.3.6.1 C.1 and F.1, Primary Containment Isolation Instrumentation and TS 3.5.3. A.1 & A.2, Isolation Condenser. A prompt investigation has been initiated to determine the cause. A troubleshooting plan is being developed. Per Tech Spec Bases Section 3.5.3, Applicable Safety Analysis, credit is taken for the Isolation Condenser in the loss of Feedwater Transient Analysis. Therefore the event is reportable under 10CFR 50.72.(b)(3)(v)(D). The licensee notified the NRC Resident Inspector. |
| ENS 40703 | 24 April 2004 15:30:00 | This report is being made in accordance with 10 CFR 50.72(b)(3)(v)(B). On 04/24/2004 at 06:03 (CDT), Dresden Unit 2 was using the Isolation Condenser to control reactor pressure following a Unit Scram. The isolation condenser operated properly until 10:50 (CDT) when the Isolation Condenser 2-1301-3 valve could not be opened to the full open position. ISO Condenser was declared INOPERABLE and Technical Specification Limiting Condition of Operation 3.5.3. Condition 'A' was ENTERED. High Pressure Coolant Injection has been administratively verified OPERABLE. Reactor Pressure is being maintained 550-1000 psig and being maintained with Reactor Water Clean Up Flow and Gland Seal System. Investigation into the cause of the valve failure is in-progress. Unit 2 had been operating approximately 30 days prior to the scram reported previously in EN #40702. The licensee informed the NRC Resident Inspector.
On April 24, 2004, Dresden made an ENS call due to the failure of Isolation Condenser valve 2-1301-3 to fully open and the subsequent determination that the Isolation Condenser was inoperable. The ENS call was made based on the decision that this was required by 10CFR50.72(b)(3)(v)(B), '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 remove residual heat.' Isolation Condenser System operation is not credited in Dresden's accident analyses. Transients and Events treated as transients are listed under section 15.0.2.1 of the UFSAR. Accidents are described and analyzed under section 15.0.2.2 of the UFSAR. The isolation condenser is not credited for fulfilling safety function of removal of residual heat of any accident as described in section 15.0.2.2, Accidents. In accordance with the guidance contained in NUREG 1022, 'Event Reporting Guidelines 10CFR50.72 and 10CFR50.73,' Section 3.2.7, 'Event or Condition That Could Have Prevented Fulfillment of a Safety Function,' a functional failure of the Isolation Condenser System is not reportable under 10CFR50.72(b)(3)(v)(B). Therefore, Dresden is retracting this ENS call. This Isolation Condenser System event will be described in a Licensee Event Report in accordance with 10CFR50.73(a)(2)(i)(B), 'Any event or condition which was prohibited by the plant's Technical Specifications' The licensee notified the NRC Resident Inspector. Notified R3DO (Kozak). |
| ENS 40702 | 24 April 2004 09:00:00 | This report is being made in accordance with 10 CFR 50.72 (b)(2)(iv)(B) . On 04/24/2004 at 06:03 (CDT), Dresden Unit 2 experienced an automatic Scram from 20% Reactor power due to Main Steam Isolation Valve closure, cause is under investigation. There were no Electromatic Relief or Safety Relief Valve actuations and the Isolation Condenser was initiated manually for pressure control. There were no ECCS initiations. PCIS Group 2 and Group 3 Isolations occurred as expected due to normal reactor water level decrease following the scram. All other systems responded as expected. All control rods fully inserted on the automatic scram. The electric plant is in a normal lineup and being supplied from offsite power. The licensee notified the NRC Resident Inspector. |