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AmerenUE Declares "Unusual Event" at the Callaway Nuclear Plant

AmerenUE officials declared an “Unusual Event” at the Callaway Nuclear Plant near Fulton, Mo., late last night. Unusual Event is a term established by the U.S. Nuclear Regulatory Commission (NRC) to describe a relatively minor occurrence at a nuclear power plant that could reduce the overall level of safety. No action by the public is advised.

The Unusual Event was declared at 11:22 p.m. on Sept. 6 following failure of a relief valve on the reactor coolant system chemical volume control system. The valve opened unexpectedly, allowing water from the system to flow to a collection tank. The system was isolated and an alternate system was placed into service within 17 minutes of the valve failure. During the review of plant trends and system information following the valve failure, operators identified that the amount of water flowing to the collection tank during the 17-minute period exceeded regulatory requirements. The Unusual Event was declared per plant procedures to provide appropriate notifications, to call in appropriate staff personnel, begin investigations into the event, and determine valve repair plans.

Company officials said there was no release of radioactivity to the environment as a result of this Unusual Event, and the incident presented no danger to plant workers or the public. They added that all appropriate federal, state and local agencies were notified. The plant remained operating at full power, and continues to operate at full power today.

An Unusual Event is the least significant of four emergency classifications established by the NRC. The other categories, in order of severity, are “Alert,” “Site Emergency” and “General Emergency.”

St. Louis-based AmerenUE serves 1.2 million electric and natural gas customers in Missouri. The Ameren companies serve 2.4 million electric customers and nearly one million natural gas customers across 64,000 square miles of Missouri and Illinois.

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CONTACT: Susan Gallagher, +1-314-554-2175, of AmerenUE