As airline travel changes again in response to the recent bombing plot in Britain, Hawai'i today will simulate another terrorist theat — the explosion of a nuclear device in Honolulu Harbor.

Approximately 14 federal, state and city agencies involving 500 to 1,000 people are taking part in exercise 'a Kele, simulating the detonation of a half-kiloton bomb in a shipping container on the dock.

"We're testing a number of things, and one of them is communications" between agencies, said Ray Lovell, a state Civil Defense spokesman. "We're testing the first responders and how they would detect something like this, and what measures they would take."

Although the mock explosion occurs in the harbor, "ground zero" for purposes of the exercise will be on an old runway at Bellows Air Force Station.

Edward Teixeira, vice director of state Civil Defense, said the name of the exercise uses the Hawaiian words " 'a," for hot and fiery, and "kele," for impurity, signifying radiation.

The Homeland Security Council about two years ago developed 15 national planning scenarios, including simulating an "improvised nuclear device" explosion, to test security preparedness.

The scenarios include a plague outbreak, chlorine-tank explosion, major hurricane, cyber attack and pandemic influenza, but Hawai'i is one of the first states to take on the nuclear-device planning, officials said.

State adjutant general Maj. Gen. Robert G.F. Lee previously said he didn't want to turn the exercise into a mass casualty drill, and commerce won't be affected.

"There will be no explosion, there will be no fire, there will be no radiation," Lovell said.

Instead, the exercise will be conducted over 34 hours today and tomorrow using computers and other communications to simulate impacts such as the loss of 30 percent of island communications.

Teixeira said an estimate of possible casualties showed 40 killed by the blast, 1,050 receiving injury and radiation within 900 meters, and up to 10,712 people receiving effects from the explosion, including radiation fallout.

Officials said nothing actually will take place in Honolulu Harbor. Residents around Bellows may notice emergency responders entering the base for the drill.

The Queen's Medical Center said it would test its trauma-center role in the exercise with mock decontamination and medical treatment.

Reach William Cole at wcole@honoluluadvertiser.com.