Release of radionuclides from the containment to adjacent areas

4 Release of radionuclides from the containment to adjacent areas 

As has been discussed in the preceding sections, the containment of a nuclear power plant represents a very effective passive barrier, at least for a certain period of time, for confining the radionuclides released from the reactor core and from the primary system in a severe accident. This renders possible their plate-out from the containment atmosphere by natural processes such as deposition of aerosols or, as regards iodine, formation of non-volatile compounds, as well as by the action of engineered safety features (e. g. sprays). Nevertheless, in safety considerations it has to be assumed that the containment is not a permanent and absolutly tight confinement, but that there would be several fundamental mechanisms by which a certain fraction of the radionuclides could escape from the containment. The most important of these mechanisms are 

The fundamental possibility that one or more of these release paths might open up, however, does not result in a direct transport of radionuclides to the environment. In such a case, natural as well as engineered retention mechanisms come into play these mechanisms will be discussed shortly in the following sections. 

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