Nuclear reactors are designed to minimise the risk of exposure to ionising radiation.
Shielding from the radiation produced in the reactor is provided by the steel casing of the reactor which is then surrounded by several metres of concrete.
Radioactive waste materials.
Low level waste like protective clothing and obsolete equipment is buried underground.
Intermediate waste like parts of the reactor or fuel cladding are put in steel drums and encased in concrete for storage underground.
High level waste like very radioactive materials or unwanted fission products are fused into glass blocks (vitrification) and stored underground.
Emergency shut down
If the rate of the nuclear fission reaction is increasing or if there is some other emergency then the reactor is shut down by dropping the control rods into the core of the reactor.