ENS 46496

v t e ENS Event
09:57 Dec 20, 2010
Title	Fuel Pool/Reactor Building Exhaust Plenum Primary Power Supply Failed
Event Description	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 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> LCO. The licensee has notified the NRC Resident Inspector.

ENS 46496 +/-
Where
Monticello Minnesota (NRC Region 3)
Reporting

10 CFR 50.72(b)(3)(iv)(A), System Actuation
Time - Person (Reporting Time:+2.48 h0.103 days <br />0.0148 weeks <br />0.0034 months <br />)
Opened:	Tom Proell 12:26 Dec 20, 2010
NRC Officer:	John Knoke
Last Updated:	Dec 20, 2010
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v • d • e

v t e Emergency Notification System
Monticello with 10 CFR 50.72(b)(3)(iv)(A), System Actuation
WEEKMONTHYEAR2024-02-28T14:39:00 [Table view]
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