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Wednesday
Jan292014

Jack Frost plays havoc with U.S. nuclear power plants

Winter weather conditions in January 2014 pointed out how nuclear power plants are unreliable power generators just when communities dependent upon electricity need them the most.

Nuclear power plants completely rely upon the electric grid system to power all reactor safety systems during power operations. If the grid is unstable or interrupted, nuclear power plants shut down and are unavailable until stable grid conditions are restored. Take for example, January 21, 2014, both Units 1 and 2 at the Calvert Cliffs nuclear generating station in Lusby, Maryland automatically shut down when snow and ice caused an electrical short-circuit in a ventilation louver. The electrical power supply shorted out to reactor safety systems including motors needed to move both reactors’ control rods, a malfunction in Unit 1’s main turbine control system and the circulating-water pumps for Unit 2. Emergency diesel generators for both units started up to provide backup power and successfully shut down the reactors. 

Nuclear power plants also require tremendous amounts of water to keep the hot reactor cores from overheating during power operations and following shutdown. Ice flows getting sucked into the intake structures restricts vital cooling water to the reactor causing nukes to shut down like what happened to New Jersey’s Salem nuclear power plant in 2010.  Since the nukes have to be located on or near large water systems like rivers, lakes, reservoirs or the ocean, they also have to be protect the intake structures from ice. When these protective measures are reduced or lost, the reactors have to shut down.  This just happened on January 9, 2014 when the Fort Calhoun nuclear power station on the Missouri River had to manually shut down power production because sub-freezing weather caused an ice buildup on one of six flood protection gates preventing the gate from closing.  Fort Calhoun had just restarted after being closed for nearly three years after flood waters surrounded the nuclear power plant for weeks.

An investigation is still ongoing into whether cold weather was the cause of the 23 day shutdown of the Pennsylvania's Beaver Valley nuclear power station on January 6th when a ruptured fire suppression system sprayed Unit 1's electric transformer with water which immediately froze, failed and caused the unit to shutdown.