British nuclear testing in the Great Victoria Desert - Kittens

As well as the major trials, there were also minor trials or "assessment tests" carried out at Emu. These were code-named kittens , and were the most secretive aspect of the entire U.K. weapons testing program. These were carried out with virtually no Australian input beyond logistic and administrative support, in fact, the Australian Government were not advised originally that the tests were even to take place, nor approved them!

There were five kitten trials at Emu. Atomic bombs require a large number of neutrons at the moment the high explosive compresses the fissile material. The neutron initiator is a radioactive substance that is brought into contact with beryllium by means of a chemical explosive. The high explosives in these "minor" tests dispersed a short-lived radioisotope, polonium-210, and less than 36g of beryllium. Polonium has a half life of 38 days and has by now decayed to an insignificant level. The Emu kittens site was occupied by security guards until 1955. The kittens were exploded on asbestos mats, and the asbestos was dispersed with the other fissile material, however the kitten trial area at Emu has now been considered "safe". Sadly other minor trials, especially the vixen sites at Maralinga have dispersed large quantities of plutonium, with a half life of 24,000 years.

More information on the nuclear testing:

Totem One
Totem Two
Kittens
Ground Zero
The clean up
Emu today
The black mist incident