Nebraska Public Power District’s Cooper Nuclear Station, an electric power plant three miles southeast of Brownville, Nebraska, declared a “Notification of Unusual Event” just after 5:45 Friday morning. The declaration was made when the Missouri River reached 899.05 feet at the plant.
The declaration was anticipated for several days by the power plant’s operators, who closely tracked the river’s steady increase in elevation due to the combination of snow melt, frozen ground, heavy rain conditions in Nebraska , and releases of water from upstream reservoirs in South Dakota.
The notification was made as part of a safety and emergency preparedness plan the station follows when flooding conditions are in effect. The plan’s procedures dictate when the Missouri River’s water level reaches 42.5 feet, or greater than 899 mean sea level, a notification of unusual event is declared.
There is no threat to plant employees or to the public at this time as the plant continues to operate safely.
Site personnel had been monitoring the river’s water levels as part of normal operations and began additional preparations in anticipation of higher volumes of water earlier in the week. Personnel have been proactive in preparing the station for flood conditions by filling sandbags that were placed along the river levee and procuring materials and supplies for flood protection.
Should the river’s level increase to 900 feet above sea level, plant personnel will also barricade internal doorways as another layer of protection for facility equipment. If the river’s level increases to 45 feet or 901.5 feet above sea level, plant operators would take the station offline as a protective safety measure.
A Notification of Unusual Event is the lowest and least serious of four emergency classifications established by the Nuclear Regulatory Commission for nuclear power plants. If placed on a scale of 1 to 4, with 1 being the least serious level of an emergency and 4 being the most serious level of an emergency, a “Notification of Unusual Event” would equal a 1.