Three types of exposure situations are intended to cover the entire range of exposure situations. The three situations are:

1 Planned exposure situations, which are situations involving the planned introduction and operation of sources of radiation. (This type of exposure situation includes situations that were previously categorized as ‘practices’.)

2 Emergency exposure situations, which are unexpected situations such as those that may occur during the operation of a planned situation, or from a malicious act, requiring urgent attention.

3 Existing exposure situations, which are exposure situations that already exist when a decision on control has to be taken, such as those caused by natural background radiation.