The concept of containment is to provide a series of barriers between the radioactive products of the fission process and the public. Any reactor has several such barriers, and the LMFBR has more than most. They are, successively: ceramic fuel that retains fission products; fuel-pin cladding; sodium coolant which absorbs radioactive iodine; primary circuit and vessel containment; containment building (possibly of two barrier construction); and exclusion distances.

This chapter is concerned with the latter two forms of containment: the containment building itself, which provides the final barrier to a release of radioactivity, either from normal refueling or waste removal operations or from accident conditions, and exclusion distances around the reactor itself.