This video series from the Canadian Nuclear Safety Commission (CNSC) explains the main safety systems of Canadian nuclear power plants. Part 4 presents the main systems involved to ensure radiation is contained, both during normal operation and in the unlikely event of an accident.
(Available in French on CurioCité)
Also be sure to check out the CANDU Inspection and CANDU Extreme Events Simulation
interactive activities which are part of CNSC Online from the Canadian Nuclear Safety Commission.