21 Jun (NucNet): The slowly rising level of the Missouri river near the Cooper nuclear power plant in the US poses no threat to plant workers or to the public and the plant continues to operate safely, owner and operator the Nebraska Public Power District (NPPD) has said.
The single boiling water reactor unit, in the state of Nebraska, declared notification of an unusual event (NOUE) on 19 June 2011, as part of safety and emergency preparedness plans the plant follows when flooding conditions are in effect, the NPPD said.
The plans dictate that when the Missouri river’s water level reaches 13.0 metres, or greater than 274.0 m above mean sea level (MSL), an NOUE is declared.
If the river’s level increases to 13.9 m or 274.9 m MSL, plant operators would take the plant offline as a preventive measure. The plant was built at 275.2 MSL, which is 4.0 m above natural grade, the NPPD said.
An NOUE is the lowest and least serious of four emergency classifications established by the US Nuclear Regulatory Commission (NRC) for nuclear power plants. In December 2010, the NRC renewed Cooper’s operating licence for an additional 20 years.
Earlier this month, an NOUE was also declared at Nebraska’s Fort Calhoun nuclear power plant because of the rising level of the Missouri river. Fort Calhoun has been safely shut down since last April for refuelling and remains in that condition.
Fort Calhoun is a single pressurised water reactor. The plant’s licence was renewed for an additional 20 years in 2003. The NRC said last year that plant owner and operator Omaha Public Power District made a number of changes to their strategy to protect the plant from severe flooding as a result of an NRC inspection and implemented a number of practical measures to protect local power supply against flood impact.
