 I'm Peter McArthur, WDEL News. Residents in parts of Delaware can expect to hear a three to five minute siren test tonight. DEMA will be testing the alert system for the Salem and Hope Creek nuclear power plants at about 7.20 p.m. The siren warns those within 10 miles of the reactors to listen to WDEL for an emergency alert message. The radius includes parts of Delaware City, Middletown, Odessa and Townsend. The test held four times a year.