ENS 47460

v t e ENS Event
05:12 Nov 20, 2011
Title	Automatic Reactor Scram While Performing Turbine Bypass Valve Testing
Event Description	While performing a regularly scheduled Turbine Bypass Valve surveillance, prior to Turbine Bypass Valve movement, a 'B' half scram [signal] was received. Operators immediately suspended testing. Approximately 10 seconds later, a full Reactor Protection System actuation occurred. Following the reactor scram, reactor water level lowered below the Group II isolation initiation setpoint of +9 inches, [resulting in containment valve isolations]. There were no radioactive releases associated with this event. No other alarms were received prior to the RPS actuation. The cause of the reactor scram is under investigation at this time. Also, due to the reactor scram, discharge canal temperature rate of change exceeded plant requirements. As a result, the State of Minnesota, and appropriate local agencies will be notified. All control rods inserted and the scram is considered uncomplicated. The plant is in a normal shutdown electrical configuration. The licensee notified the NRC Resident Inspector.

ENS 47460 +/-
Where
Monticello Minnesota (NRC Region 3)
Reporting

10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(iv)(A), System Actuation
Time - Person (Reporting Time:+-3.03 h-0.126 days <br />-0.018 weeks <br />-0.00415 months <br />)
Opened:	Mark Ihlenfeldt 02:10 Nov 20, 2011
NRC Officer:	Vince Klco
Last Updated:	Nov 20, 2011
47460 - NRC Website Loading map...
v • d • e

v t e Emergency Notification System
Monticello with 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation
WEEKMONTHYEAR2025-07-29T01:58:00 [Table view]
[ENS list for Monticello]

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