Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 50639 | 25 November 2014 16:32:00 | On Tuesday, November 25, 2014, at 1200 EST, the FirstEnergy Nuclear Operating Company (FENOC) reviewed AREVA 10CFR50.46 Notification Letter FAB14-00625 for the Davis-Besse Nuclear Power Station (DBNPS). This letter indicates that certain non-conservatisms were discovered in the methodology application and inputs used by AREVA for nuclear fuel core configurations with Mark-B-HTP fuel when operated under certain conditions. When corrected, this increases the Peak Cladding Temperature (PCT) in excess of the value prescribed in 10CFR50.46(b)(1) under Loss of Coolant Accident (LOCA) conditions. The DBNPS reactor core contains Mark-B-HTP fuel. 10CFR50.46 paragraph (b) defines the acceptance criteria for the LOCA analysis process. The DBNPS licensing basis PCT is evaluated for compliance with and must not exceed the criterion prescribed in 10CFR50.46(b)(1). AREVA had provided compensatory measures in terms of plant axial imbalance limits and Fq linear heat rate limits associated with reductions in LOCA linear heat rates so that the DBNPS operates within 50.46 limits. FENOC implemented the compensatory measures at the DBNPS on October 23, 2014, per AREVA recommendations, and as a result the errors reported have no impact on current plant operation or public health and safety. Preliminary analysis of past operating conditions indicate that the DBNPS did not exceed the 50.46(b)(1) criteria for PCT. This 8-hour notification is being reported in accordance with 10CFR50.72(b)(3)(ii)(B). Based on 50.46(a)(3)(ii) criteria, FENOC will submit a report within 30 days for the DBNPS. FENOC has notified the DBNPS NRC Senior Resident Inspector. |
| ENS 47670 | 16 February 2012 15:03:00 | At approximately 0542 hours (EST), the Safety Parameter Display System (SPDS) became non-functional, and therefore was not available in the Control Room or in the emergency response facilities. Efforts are underway to restore the system, but as of 1342 hours (EST) these efforts have not been successful. The loss of SPDS for more than 8 hours is being reported in accordance with 10 CFR 50.72(b)(3)(xiii). Troubleshooting efforts continue to restore the SPDS. The Emergency Response Data System (ERDS) remains functional, and the station remains capable of performing dose assessment using manual inputs per site procedures. The Control Room also continues to have the capability to retrieve plant data inputs to assess plant conditions and perform core damage assessments. The NRC Senior Resident Inspector has been notified, and the State of Ohio Emergency Management Agency will be notified.
As of 2100 EST on 02/16/12 the SPDS has been restored to service and is functioning properly. The licensee will inform the NRC Resident Inspector. Notified R3DO (Passehl). |
| ENS 46551 | 19 January 2011 03:10:00 | An electrical fire and explosions were reported near the Containment Access Facility construction area. An Unusual Event was declared based on HU4. Temporary electrical power at service disconnect DSLM3-3 was isolated. The fire was out at 0243 EST. The fire was extinguished using dry chemical. The fire was reported at 0232 EST on 1/19/11. The cause of the fire has not been determined at this time. The fire and explosions were initially reported by site security personnel. The licensee declared the NOUE at 0243 EST based on criteria HU4. The licensee initially called for offsite assistance in putting out the fire, however, the fire was extinguished by plant personnel and the offsite assistance was turned back. The licensee posted a reflash watch. The fire reportedly involved temporary cables and possibly a transformer supplying power to the construction area which is located inside the protected area outside the auxiliary building. The licensee notified the NRC Resident Inspector.
The licensee terminated the Notification of Unusual Event at 0358 EST. No additional information is available at this time. Notified R3DO (Bloomer), NRR EO (Skeen), IRD (Gott), DHS (Stringfield), and FEMA (Casto). |