Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 43047 | 12 December 2006 16:59:00 | On December 12, 2006, at 1322 PST, while conducting power ascension operations with Unit 2 at approximately 25 percent power, an electrical failure occurred in the Unit 2 circulating water pump motor enclosure (CWP) 2-1. A loud bang and explosion was reported to the Unit 2 control room. At 1322 PST, an electrical transient was experienced on Unit 2 12-Kv non-vital bus 'D' which in turn caused reactor coolant pump (RCP) 2-2 and RCP 2-4 motor breakers to trip on 12kV non-vital bus 'D' undervoltage, initiating an automatic reactor trip. The reactor trip signal was initiated when 2 out of 4 RCP motor breakers opened. All control rods fully inserted in response to the reactor trip and all plant systems functioned as required. The auxiliary feedwater system for Unit 2 was manually actuated per plant procedures, before an auto-start signal for this system was generated. At 1356 PST, DCPP Fire Department first responders reported that the fire was out. At 1340 the licensee declared a Notice of Unusual Event (NUE), number 23, 'Confirmed Explosion Onsite'. Decay heat is being removed via auxiliary feedwater to the steam generators steaming to the atmospheric dump valves. Emergency power is being supplied via offsite power. The NRC resident inspector has been informed and was onsite at the time of the Unit 2 reactor trip. Diablo Canyon Power Plant (DCPP) Unit 2 is presently in Mode 3. There were no injuries associated with this event. Investigations into the electrical transient are ongoing. DCPP Unit 2 will remain in Mode 3 pending the results of this investigation. An estimated restart of DCPP Unit 2 is not known at this time. DCPP Unit 1 is unaffected and remains in Mode 1 at 100% power. * * * UPDATE AT 1730 EST ON 12/12/06 FROM T. CHITWOOD TO P. SNYDER * * * The licensee terminated the Unusual Event at 1430 PST. The Notice of Unusual Event was terminated due to the fact the licensee assessed the damage to the circulating water pump and determined that the explosion was caused by a breaker in the local area. The licensee fire brigade was satisfied that the fire was extinguished and that the damage was confined to the local area of circulating water pump 2-1. The licensee notified the NRC Resident Inspector. Notified the R4DO (Smith), NRR EO (Highland), IRD (Wilson), DHS (Inzer), and FEMA (Discoe). * * * UPDATE AT 1841 EST ON 12/12/06 FROM T. CHITWOOD TO J. ROTTON * * * The licensee provided an update to make the formal 4 hour notification pursuant to 10 CFR 50.72 (b)(2)(iv)(B) due to the RPS actuation while critical, and the formal 8 hour notification pursuant to 10 CFR 50.72 (b)(3)(iv)(A) due to the actuation of the auxiliary feedwater system. The licensee notified the NRC Resident Inspector. Notified the R4DO (Smith), and NRR EO (Highland). |
| ENS 41076 | 28 September 2004 13:44:00 | Earthquake felt at plant site (at 1015 PDT) registering 0.012 g. No damage on plant site noted. Release to the environment remains within normal operating levels, and effluent radiation monitors did not alarm. No protective action required. The Licensee notified the NRC Resident Inspector.
Plant walk down in progress. No damage noted." The Licensee notified the NRC Resident Inspector.
Information Call: No plant damage detected by walk downs or equipment testing. R4DO (Linda Howell) notified. The Licensee will notify the NRC Resident Inspector.
Information Call: No plant damage detected by walk downs or equipment testing. The licensee notified the NRC Resident Inspector. R4DO(Howell) will be notified.
The licensee terminated the NOUE at 1215 PDT. "No plant damage has been detected by plant walkdowns or equipment testing." NRC exited Monitoring at 1600 EDT Notified R4DO (L Howell), NRR (Skeen, Borchardt), IRD (Frant, Wilson), Chairman Office (Holahan), EDO (Mitchell), PAO, Dir of Comm. (Outlaw), DHS (Morison), FEMA (Caldwell), USDA (Thomas), DOE (Wyatt), NRC DOT (Crews), and HHS (R. Harlan) |