Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 49938 | 20 March 2014 17:17:00 | At 1020 CDT, door 410B did not automatically close and latch as required. Door 410 B is an Appendix R fire door that is required for divisional separation of safe shutdown equipment. Due to the doors inability to close and latch as required, divisional separation could not be assured in the event of a fire. A continuous fire watch was established once the deficiency was discovered. The door was repaired and verified to be working properly. The door was non-functional for approximately one hour and fifteen minutes from the time of discovery. Health and safety of the public was maintained as the plant was in a normal condition and there has been no actual condition needing the door to close and latch. The NRC Resident Inspector has been notified. |
| ENS 47782 | 28 March 2012 18:19:00 | On 3/28/2012, Xcel Energy Personnel determined that approximately 50% of the Amertap balls recently used were not recovered. A survey of the Mississippi River bank downstream of the plant by site personnel recovered an additional 3 Amertap balls, indicating that the balls were not released to the river. Monticello Nuclear Generating Plant (MNGP) is required to report to the Minnesota Pollution Control Agency (MPCA) when greater than 20% (1 .5 barrels or approximately 7,500) of the Amertap balls are not recovered. This is based on an agreement with the MPCA dated September 12, 2008. The MPCA was notified at 1648 CDT on 3/28/12. The NRC Resident Inspector has been notified. |
| ENS 47364 | 21 October 2011 16:42:00 | The station experienced a lockout of the 2R Auxiliary Power Transformer. The resulting transient caused an automatic actuation of the RPS system. All control rods fully inserted. A Group 2 Primary Containment isolation occurred. Both 11 and 12 Emergency Diesel Generators started on a loss of voltage signal. Equipment response was that the 11 ESW (Emergency Service Water) pump (cooling for the #11 Emergency Diesel) failed to develop required pressure. The #13-4160V non-safety related bus failed to restore after the transient (and feed the Division 1 Essential Bus). Additionally, the #15 bus transferred to the 1AR transformer (and is feeding the Essential Bus). The #11 Emergency Diesel Generator is currently tagged out of service. Electrical supply is being provided by offsite power. Reactor heat is being removed through the main steam line to the main condenser and reactor water inventory is being provided by the feedwater system. The SRVs lifted and reseated. The HPCI system was manually place into a pressure control mode. The Minnesota Pollution Control Agency is being notified due to the licensee violating the site discharge canal temperature rate of change limit. The licensee notified the NRC Resident Inspector.
Prior to this event the 'B' Control Room Emergency Filtration (CREF) and 'B' Control Room Ventilation (CRV) Systems were inoperable for planned maintenance. On 10-21-11 at 1325 CDT, the #11 EDG ESW Pump was declared inoperable due to low cooling water pump flow, resulting in the #11 EDG being inoperable, which in turn resulted in the 'A' CREF and 'A' CRV being inoperable. Contrary to reporting requirements this condition was not identified and reported pursuant to 10 CFR 50.72(b)(3)(v)(D) as required within 8-hours in the previous event notification. This condition resulted in a loss of safety function for both divisions of CREF and CRV. This update amends the 10-21-11 event notification to include this as an 8-hour non-emergency event pursuant to 10 CFR 50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector. Notified the R3DO (Nick Valos) |
| ENS 46496 | 20 December 2010 12:26:00 | At 0357 December 20, 2010 the 'A' division Fuel Pool/Reactor Building Exhaust Plenum Primary Power Supply failed, resulting in upscale readings on both the Fuel Pool and Reactor Building Ventilation Plenum radiation monitors. This condition resulted in closure of the Group II Primary Containment Isolation Valves (PCIV), isolation of Secondary Containment (SCT), initiation of the Standby Gas Treatment System (SBGT), and a transfer of the Control Room Ventilation (CRV) and Control Room Emergency Filtration (CREF) systems to the High Radiation Mode. Conditions and Required Actions were entered for Technical Specification 3.3.6.2 (SCT Instrumentation), 3.3.7.1 (CREF Instrumentation), and 3.4.5 (RCS Leakage Detection - CAM). Radiation levels were verified to be normal in the affected areas. Isolations signals were reset and Secondary Containment ventilation systems were restored to a normal lineup. Repairs are currently in progress to replace the high voltage power supply to the affected radiation monitors and are expected to complete within the required action time limits of the applicable technical specifications. The licensee is in a 24 hour LCO. The licensee has notified the NRC Resident Inspector. |