Radiation protection applies to all conceivable radiation exposure situa­tions, which can be classified as planned, emergency and existing exposure situations, as follows (ICRP, 2007a):

• Planned exposure situations refer to circumstances involving the planned introduction and operation of sources that may expose people to radiation.

• Emergency exposure situations refer to unexpected accidental condi­tions that may occur during the operation of a planned situation, or from a malicious act, and which require urgent protective attention.

• Existing exposure situations refer to a radiation environment that already exists when a decision on control has to be taken, e. g., natural back­ground radiation exposure situations.

For NPPs, the design and operation stages are clearly planned exposure situations. If an accident occurs, it should be treated as an emergency expo­sure situation. The residual risks that might remain after the decommission­ing and closure of NPPs may be treated as an existing exposure situation (Gonzalez, 2009b).