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| Entered date | Event description | |
|---|---|---|
| ENS 42916 | 17 October 2006 18:07:00 | At 1430 CDST on 10/17/2006 the Control Room was notified by the Site HVAC engineer that a condition existing in the Technical Support Center (TSC) HVAC called into question the habitability of the TSC under accident conditions. Specifically, the TSC HVAC Supply fan was noted on the previous shift to be putting out less air than normal. Engineering was asked to look into it and discovered that the fan belts were slipping and that the fan was currently running at approximately half normal speed. While this was sufficient to maintain the required positive pressure in the TSC at the present time, they were not confident of it's ability to maintain it long-term under accident conditions. Receipt of this information and consultation with Southern Nuclear Company Emergency Preparedness employees has led the Control Room staff to the decision to make this notification under 10CFR50.72(b)(3)(xiii), for a major loss of emergency assessment capability due to the uncertainty of the long-term habitability of the TSC. Preparations are underway for the repair of the affected fan, which is expected to be completed tonight. The licensee notified the NRC Resident Inspector. |
| ENS 42915 | 17 October 2006 17:50:00 | On October 14th V.C. Summer Nuclear Station shut down for a routine refueling outage. At 1415 on October 17, 2006 during an inspection of the reactor vessel upper head, personnel identified a small leak in a weld in the Reactor Vessel Level Instrumentation System (RVLIS). This weld is located in a 3/4 inch stainless steel instrumentation line. The line is attached to, and is approximately three feet from the reactor vessel head. This leak resulted in a small amount of boron accumulation in an isolated area. There is no indication that any safety systems were affected. The licensee notified the NRC Resident Inspector.
EN #42915 was submitted by South Carolina Electric & Gas Company based on the initial indication of a pressure boundary leak in the Reactor Vessel Level Instrumentation System (RVLIS). South Carolina Electric & Gas Company retracts EN #42915 based on the following discussion. During subsequent cleaning and inspection of the suspect weld, which was preserved in its as-found condition for root cause analysis, no flaw in the analyzed RVLIS piping or pipe coupling was found. Further investigation was conducted of the area under the Control Rod Drive Mechanism (CRDM) shroud near the RVLIS line. The source was determined to be leakage through the lower canopy seal weld of CRDM No. 25, which resulted in accumulation of boric acid on the suspect RVLIS line. Since the RVLIS line was not leaking and the CRDM canopy connection is a mechanical (screwed) fitting with a seal weld, there has been no pressure boundary leakage as defined by Technical Specifications. The canopy seal weld is neither a structural weld nor a pressure retaining weld comprising the reactor coolant system pressure boundary. A permanent plant design was developed and the canopy seal was repaired using a standard canopy seal clamping process. A 100 % bare metal visual inspection of the reactor vessel head was completed during this refueling outage. The results confirmed that there has been no degradation. The licensee will notify the NRC Resident Inspector. Notified the R2DO (Evans) |
| ENS 41665 | 4 May 2005 15:20:00 | At 1432 on May 4, 2005, V.C Summer declared a Notification of Unusual Event (NUE) due to a small fire in the reactor building that lasted for more than 15 minutes inside the protected area of the plant. The reactor was defueled at the time. There were no injuries, radiological conditions remained unchanged, and no safety related equipment was affected. Personal were not required to evacuate the building and the fire brigade was not activated. The resident NRC inspector and all appropriate state and local officials were notified. There was no radiological release. Details are as follows: At 1410, a health physics technician noticed smoke in the refueling cavity. Upon investigation, it was noted that a temporary lighting power cord had electrically shorted. The power source was isolated at 1420. The electrical short had ignited a small patch of strippable coating that was applied to the cavity floor for contamination control. The resulting flames were extinguished with demineralized water at 1430. A NUE was declared at 1432 in accordance with licensee procedure EPP-001, Activation and Implementation of Emergency Plan. The area was monitored to ensure that there were no further issues and the NUE was downgraded at 1517. |
| ENS 41114 | 11 October 2004 13:51:00 | On October 11, 2004, at 1057 (hrs. EDT) , while performing modification work to support security upgrades, the radio system controller that activates the plant offsite warning system was removed from service during a pre-planned activity. At 1148, the system was rebooted but failed to perform correctly. Approximately 70 % of the sirens were communicating with the system, while plant procedures direct that less than 75 % of the offsite warning system meets the reporting threshold. At 1226, the offsite warning system capability was restored to greater than 75%. Since the removal of the offsite notification network from service was a planned evolution, the county, state and the NRC resident inspector were notified prior to the removal from service. Appropriate compensatory measures were taken by the state and local agencies. The cause of the event was the new Federal Signal activation frequency not reloading after the outage since it was not hard-coded into the software for the radio system controller. This caused all 27 of the Federal Signal sirens from being activated. Three other sirens had pre-existing conditions which made 30 sirens inoperable out of a total of 106. The correct information was loaded into the software via modem and a silent siren test confirmed 93% capability at 1226. The frequency information was hard coded into the software to prevent future occurrences. The licensee notified state/local agencies and the NRC resident inspector. |
| ENS 40628 | 30 March 2004 17:38:00 | On March 30, 2004, while at power, VCSNS (V.C. Summer Nuclear Station) personnel were performing a reactor building inspection to identify the source of reactor coolant system unidentified leakage that was within Technical Specification (TS) limits. At 1129 hours, a pressure boundary leak was identified at the seal injection line to reactor coolant pump 'C'. Pursuant to TS 3.4.6.2, Action a., VCSNS commenced a controlled reactor shutdown at 1410 on March 30, 2004. During the shutdown, the main turbine experienced higher than normal vibration. At 1516, the turbine was manually tripped at approximately 43% reactor power. Subsequent to the turbine trip, feedwater regulating valve IFV-498 failed in the closed position while in automatic with a full open demand signal. The cause of this failure is not known. The reactor automatically tripped at 1520 due to lo-lo level in the 'C' steam generator at 10% reactor power. All control rods fully inserted and all safety systems responded normally. Both motor driven emergency feedwater pumps started as required. The plant stabilized in mode 3. The licensee notified the NRC Resident Inspector. |