Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 52226 | 8 September 2016 04:27:00 | On September 7th, 2016 at approximately 2131 Mountain Standard Time (MST), Palo Verde Unit 1 was manually tripped due to a stuck open main spray valve. Unit 1 was operating at 100 percent power at normal operating temperature and pressure prior to the event. A 120 VAC non-class instrument distribution panel was being transferred to its alternate power supply to establish maintenance conditions. The distribution panel failed to transfer. The panel remained energized from its normal power supply; however, multiple components powered from the distribution panel began to exhibit uncharacteristic behavior. At this time, it was noted that a reactor coolant system main spray valve was open. The alarm response procedure was followed; however, the actions taken were unsuccessful at closing the main spray valve. The plant was then manually tripped due to pressurizer pressure continuing to lower. The reactor coolant pumps were turned off to terminate main pressurizer spray flow to control pressurizer pressure due to the inability to close the main spray valve. No ESF (Engineered Safety Features) actuations occurred and none were required. No emergency classification was required per the emergency plan. Safety related buses remained energized during and following the reactor trip. The emergency diesel generators did not start and were not required. The offsite power grid is stable. Limiting condition for operation 3.4.1 was entered due to low pressurizer pressure. No major equipment was inoperable prior to the event that contributed to the event. Unit 1 is stable at normal operating temperature and pressure in Mode 3. Reactor coolant pumps are secured and natural circulation has been verified. Primary pressure is being maintained at its normal operating pressure manually with pressurizer heaters and auxiliary spray, from the charging system. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The minimum RCS pressure was approximately 2070 psia (normal 2250). The event did not adversely affect the safe operation of the plant or the health and safety of the public. All rods inserted and the trip was uncomplicated. Units 2 and 3 were not affected and continue to run at full power. The NRC Resident Inspector has been notified. |
| ENS 46167 | 11 August 2010 13:04:00 | While repairing a control room alarm panel, a screw was dropped. This appears to have caused a breaker (3D1B-27) to trip, which caused a loss of greater than 50% of the control room alarm panels. A team is being assembled to develop trouble shooting plan to restore alarm panels. Enhanced plant monitoring is being put in place until alarm panels are restored. Approximately half of the control room annunciators are locked in and/or non-functional. The licensee notified the NRC Resident Inspector. Notified DHS (Hill), FEMA (Heyman), DOE (Yates), HHS (Baker) and USDA (Shaffer).
At 2130 EDT, Unit 3 exited from the UNUSUAL EVENT based on returning to service greater than 50% of alarm panels. Compensatory measures are in place for the alarm panels which have no audible signal. The licensee notified appropriate state and local agencies. The licensee also notified the NRC Resident Inspector. Agencies that the licensee notified included South Carolina and North Carolina warning points, the South Carolina Emergency Management Agency and the Oconee and Pickens County Emergency Management Agencies. Notified R2DO (Desai), NRR EO (Nelson), IRD Manager (Gott), DHS ( Gates), FEMA (Blankenship), DOE (Bailey), HHS(Grimes) and USDA (Timmons). |
| ENS 40366 | 1 December 2003 22:27:00 | Polar crane operator experienced a medical condition that required immediate transport to the local hospital. The individual's Anti-contamination clothing were removed in a contaminated area of the Containment building by medical responders and the individual with the medical condition was identified as being contaminated. No specific contamination level was available at the time of the initial report other than he was frisked and the level was above background. It was also not known what the general level of contamination in the immediate vicinity of the individual was at the time of the initial report. A licensee Radiation Protection Technician escorted the individual to a local hospital in an ambulance. After arrival at the hospital, the individual's modesty garments were removed and the individual was no longer contaminated. Modesty garments were disposed of and the ambulance was surveyed and determined to by uncontaminated. The transported individual is in stable condition. The licensee notified the NRC Resident Inspector. No media or press release is expected to be made at this time. |