Answer is: encasing nuclear waste in containers that are then taken to remote locations.
Nuclear (radioactive) waste is hazardous to all forms of life and the environment.
Long term storage of radioactive waste is needed. It is important the stabilization of the waste into a form which will neither react nor degrade over many years.
If nuclear waste is wasted in atmosphere or into oceans and lagre lakes, eventually it will come in contact with living organisms.