Radiation is the emission of energy. Contamination is the presence of radioactive material in places where it is undesirable for one reason or another. We are discussing, for the most part, the latter.
Accidents involving widespread contamination depend on the accident dynamics and the system design. Often, the latter strongly influences the former. This is especially true for incorrect attempts to equate accident scenarios possible for the RBMK design to those of LWR systems. Its like comparing the damage potential of a blockbuster to that of a wet firecracker. You can try it, but you'll come off looking somewhat foolish and ignorant.