Because," he said slowly, "a few minutes after we blast off there will be nothing in this neighborhood but a nice, pretty radioactive cloud.

Physical reactions cause the radioactive cloud that does leave the site to become increasingly diluted as it moves away from the plant.

Lucy felt the scream sticking in her throat, and knew she was walking through radioactive clouds.

She hoped they were far enough from the radioactive cloud.

Her body is nothing but particles in a radioactive cloud.

He was thankful the attack hadn't resulted in a radioactive cloud.

How the hell can there be a radioactive cloud?

If it works, that radioactive cloud will have had more time to blow away.

When melted, the caesium-137 caused the release of a radioactive cloud.

They can take on various forms and appearances, but their natural form is a free floating radioactive cloud.