- Associated Press - Tuesday, March 27, 2012

Hollywood has often destroyed Washington — or New York or Los Angeles — with nuclear bombs detonated by terrorists. That turns out to be harder to do in real life.

Thinking about the unthinkable, a U.S. government study analyzed the likely effects from terrorists setting off a 10-kiloton nuclear device a few blocks north of the White House.

It predicted terrible devastation for roughly one-half mile in every direction, with buildings reduced to rubble the way World War II bombing raids destroyed parts of Berlin. But outside that blast zone, the study concluded, even such a nuclear explosion would be pretty survivable.

“It’s not the end of the world,” said Randy Larsen, a retired Air Force colonel and founding director of the Institute for Homeland Security. “It’s not a Cold War scenario.”

The little-noticed, 120-page study by the Federal Emergency Management Agency was hardly a blockbuster.

This map, released by the Federal Emergency Management Agency, shows the likely effects from a 10-kiloton nuclear device set off a few blocks north of the White House. (AP Photo/FEMA)
This map, released by the Federal Emergency Management Agency, shows the likely ... more >

Titled “Key Response Planning Factors for the Aftermath of Nuclear Terrorism,” it was produced in November by the Homeland Security Department and the National Nuclear Security Administration. Even though the government considers it “for official use only” and never published it online, it circulated months later on scientific and government watchdog websites.

The study did not examine the plausibility of terrorists building a nuclear bomb or smuggling one into Washington, which is protected with radiation sensors and other technology designed to thwart such an attack. It didn’t say why it chose the intersection of 16th and K streets Northwest as the epicenter for its fictional nuclear bomb.

The U.S. government report estimated the blast zone in Washington from its fictional attack would extend just past the South Lawn of the White House and as far east as the FBI headquarters. “Few, if any, above-ground buildings are expected to remain structurally sound or even standing, and few people would survive,” it predicted. It described the blast area as a “no-go zone” for days afterward because of radiation.

But the U.S. Capitol, the Supreme Court building, the Washington Monument, the Lincoln and Jefferson memorials, and the Pentagon across the Potomac River are all in areas described as “light damage,” with some broken windows and mostly minor injuries.

The government study predicted 323,000 injuries, with more than 45,000 dead. A 10-kiloton nuclear explosion would be roughly 5,000 times more powerful than the truck bomb that destroyed the federal building in Oklahoma City in 1995 but only about half the size of the atomic bombs dropped on Japan in World War II.

The flash from the explosion would be seen for hundreds of miles, but the mushroom cloud — up to five miles tall — would keep its shape for just a few minutes. The flash would be so bright it could temporarily blind people up to 12 miles away, including drivers on the Capital Beltway. At least four area hospitals would be heavily damaged or unable to function, and four others would experience dangerous radiation fallout.

The government said it expects to send warnings afterward by television, radio, email, text message and social-media services such as Twitter and Facebook.

It predicted the seriousness of radioactive fallout, which would drift with prevailing winds that vary depending on the season and expose victims closest to the explosion to 300 to 800 Roentgens in the first two hours, enough to kill nearly all of them.

In the spring, fallout would drift mostly to the north and west of downtown Washington. But in the summer, it would drift mostly southeast. After two hours, the radioactive cloud would move over Baltimore with far less exposure.