 Mark Fouser, WDEL, Delaware's News Radio. Residents and parts of Delaware will hear an emergency siren test tonight. DEMA will be testing the alert system for the Salem and Hope Creek nuclear power plants around 7.20 p.m. The sirens will sound for three to five minutes for those within 10 miles of the reactors. The radius includes parts of Delaware City, Middletown, Odessa, and Townsend. The tests are held four times a year.