Definition: Encapsulation is a way of disposing of something that is hazardous and potentially damaging to the environment. Although there are a number of different ways this can be done, one way is to mix the substance with cement and encase it in concrete. For example, nuclear power comes from the release of energy by radioactive fuel rods; over time these need to be disposed of. They can either be kept safely in a metal container or encased in concrete. Both metal containers and blocks of concrete can be stored underground where they are then monitored to make sure that radiation is not leaking out from them.