SPRING CITY, TN (WRCB) -- The Tennessee Valley Authority will upgrade and replace its existing 100 emergency notification sirens within a 10-mile radius of the Watts Bar Nuclear Plant beginning on January 14. 

Contractor crews will be replacing sirens at the rate of two to four units per day throughout the plant's 10-mile Emergency Planning Zone. The crews will be typically working six days a week to finish the job.  

The new sirens run on conventional electrical service, but feature a battery backup designed to keep them operating for up to a week if power is interrupted.  

"Recent tornadoes and other powerful storms in TVA's service area serve as a reminder of the importance of the sirens to the safety of the community," said Watts Bar Site Vice President, Tim Cleary. "It is vital that we ensure the sirens are effectively operating each and every day."

After installation, each siren will be tested to make sure it operates properly. This will result in individual sirens being sounded multiple times daily, six days a week, for the next two or more months, until all sirens are replaced. These soundings should last about 20 seconds. An actual activation of the warning siren would last approximately three minutes.

The Watts Bar Nuclear Plant Emergency Planning Zone includes McMinn, Meigs and Rhea counties in Tennessee. Sirens will be replaced in all three counties. 

The replacement sirens will be mounted on steel, rather than wooden poles, to increase reliability during severe weather. The new sirens will sound the same as the old ones and will continue to be tested on the first Wednesday of each month at approximately noon. 
  
Upon completion of the Watts Bar siren installation, TVA will have replaced emergency notification sirens at Browns Ferry (Athens, Ala.); Sequoyah (Soddy Daisy, Tenn.); and Watts Bar (Spring City, Tenn.). TVA is investing about $7 million to replace all sirens.