1.   American McGee chases his colleague Shawn Green through the office, leaping over acid pits and dodging radioactive debris before cornering him in a cul-de-sac.

2.   He ordered bulldozers that could bury radioactive debris.

3.   Once that is dealt with, health authorities must consider how strong the explosion was and how far it may have flung radioactive debris.

4.   That means widespread fears in Australia about the possibility of radioactive debris from the craft were moot.

5.   The issue is further confused by new evidence suggesting that the Mojave Desert may not be the safest place to bury radioactive debris.

6.   To better forecast fallout distribution, the military began taking samples of radioactive debris from a mushroom cloud within minutes after a blast.

7.   This was not the first time radioactive debris had fallen to Earth as the result of a spacecraft accident.

8.   But harsh weather has corroded the structure, and nuclear experts have warned that it could collapse and cause another explosion of the radioactive debris inside.

9.   However, remaining radioactive debris could cause contamination above normal health standards, UNEP said.

10.   It said remaining radioactive debris could cause contamination which was above normal health standards and recommended action to fence off affected sites and improve monitoring procedures.