The new emergency alert and notification siren system at Three Mile Island (TMI) will be tested on Thursday at 12:15 p.m.
The Federal Emergency Management Agency needs to test the new system to place the system in service.
Dauphin County Commissioners say the new system includes battery backup capability that will allow the sirens to sound even during power outages.
As part of the test, all 96 new sirens within 10 miles of the facility will sound for three minutes.
"Residents near TMI can be assured the sounding of the sirens is only a test, and there is no cause for concern," said Pries, who has oversight of DEMA.