[zeeshanef]

Hi,
please tell me, Why only Lead metal Is Used to stop Radioactive radiations.

Thanks

[Stepan]

Any material can be used. For some applications water performs better than Lead. On Chernobyl station (because of the large area which need to be enclosed) they used concrete.

In general, the efficiency in reducing of radiation is proportional to material thickness and its density. Because lead has high density it is commonly used to manufacture the protective shields. 

[DevaDevil]

lead is indeed very good against gamma radiation because it is so dense, just do not use it to try and stop electrons (beta radiation) or neutrons. Because lead is so dense, you can use a comparitively small shield of it, in stead of a bulky wall (Mass is important for blocking Gamma radiation)

concrete was used in chernobyl because it is cheaper, and the bulkiness of it wasnt a problem outdoors in that massive heap.