ENS 46509
ENS Event | |
|---|---|
00:25 Dec 26, 2010 | |
| Title | Notification of Unusual Event Declared Due to High Winds |
| Event Description | Notification of Unusual Event declared due to high winds. EAL HU 1.2 condition of peak wind in excess of 80 miles per hour have been met. Sustained winds at the present time are 53.5 miles per hour. Wind direction (from) 38.8 degrees. There has been no damage on-site. There are no plans to reduce reactor power on either unit at the present time. The Emergency Operations Center has not been activated. The storm front causing the high winds is expected to exit the area within the next three to four hours.
The licensee notified the NRC Resident Inspector. The licensee notified the San Luis Obispo Sheriff and the State of California Office of Emergency Services.
Current wind speed is 3.7 miles per hour. Wind direction (from) 134.7 degrees. There has been no damage on-site. The access roads to the site are open and passable.
Current wind speed 9.2 miles per hour. Wind direction (from) 101.6 degrees. The NRC Senior Resident Inspector is on-site.
The licensee terminated the NOUE at 2021 PST. Winds are less than 2 mph gusting to 2.8 mph from 63.9 degrees. The storm has passed and no damage has been detected. The NRC Resident Inspector will be notified. Notified the R4DO (Werner), IRD (Gott), NRR EO (Howe), DHS (Knox), and FEMA (Fuller).
During a rain storm on December 25, 2010, PG&E declared an Unusual Event at the Diablo Canyon Power Plant due to indicated peak wind speed of 42.6 meters per second (m/s), (95.3 miles per hour (mph)), at the 10m elevation on the Primary Meteorological Tower, in excess of 80 mph indicated. After analyzing other wind speed instrumentation from the same time period, PG&E concluded that this reading did not accurately reflect meteorological conditions at that time. The next highest reading was taken at the 76m elevation on the Primary Meteorological Tower and indicated peak wind speeds of 23.7 m/s (53.0 mph). The Backup Meteorological Tower mechanical anemometers indicated a wind speed of 16.1 m/s (36.0 mph) for the 10m elevation, and 18.2 m/s (40.7 mph) for the 60m elevation. The Primary Meteorological Tower sonic sensors read both wind speed and wind direction with a single sensor. Concurrent with the Primary Meteorological Tower 10m wind speed spike, the 10m Primary Meteorological Tower wind-direction made a step-change from 153 degrees to 39 degrees. This step change indicated a value approximately 180 degrees opposite all other wind direction instrumentation indications. PG&E made the initial reporting of this event assuming the wind speed indicator at the 10m elevation on the Primary Meteorological Tower was functioning correctly. Analysis determined that this instrument was not functioning correctly. PG&E troubleshooting found the sonic wind speed and direction sensors are vulnerable to moisture intrusion. Moisture was found in the body of a wind speed and direction sensor after it had spiked in the rain. The vendor confirmed that moisture on the circuit board could cause an interruption of measurement, which would cause the sensor outputs to read high. PG&E identified moisture intrusion as the presumptive cause of the wind speed spiking . PG&E has sealed all sensors to eliminate the vulnerability. Given the above, PG&E retracts this event report. Notified the R4DO (Miller). |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-4.75 h-0.198 days <br />-0.0283 weeks <br />-0.00651 months <br />) | |
| Opened: | James Ewart 19:40 Dec 25, 2010 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Jan 28, 2011 |
| 46509 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 528762017-07-28T19:06:00028 July 2017 19:06:00
[Table view]10 CFR 50.72(a)(1)(i), Emergency Class Declaration Alert Declared Due to Low Oxygen Levels Inside Containment ENS 516552016-01-14T22:43:00014 January 2016 22:43:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event - Security Condition That Does Not Involve Hostile Action ENS 484272012-10-21T07:09:00021 October 2012 07:09:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Seismic Event ENS 466682011-03-11T09:23:00011 March 2011 09:23:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event as a Result of a Tsunami Warning in the Area ENS 465092010-12-26T00:25:00026 December 2010 00:25:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Declared Due to High Winds ENS 460362010-06-23T17:48:00023 June 2010 17:48:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Alert Declared for a Cardox Discharge in the Turbine Building ENS 459922010-06-09T18:12:0009 June 2010 18:12:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Toxic Gas/Chemical Spill in the Protected Area ENS 451122009-06-02T08:22:0002 June 2009 08:22:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event - Smoke Alarm in Protected Area Lasting Greater than 15 Minutes ENS 444192008-08-17T07:12:00017 August 2008 07:12:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Fire in Main Bank Tranformer ENS 443572008-07-21T16:08:00021 July 2008 16:08:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared - Unable to Validate a Fire Alarm within 15 Minutes ENS 430472006-12-12T21:22:00012 December 2006 21:22:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Circulating Water Pump Failure Causes Explosion in Intake Structure ENS 417742005-06-15T03:50:00015 June 2005 03:50:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Due to Tsunami Warning ENS 410762004-09-28T17:30:00028 September 2004 17:30:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Seismic Activity ENS 404082003-12-22T19:22:00022 December 2003 19:22:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event - Earthquake ENS 402582003-10-18T07:52:00018 October 2003 07:52:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Earthquake Felt on Site. Entered Emergency Action Level (Eal) 18 2017-07-28T19:06:00 | |