Assessment of doses from normal discharges

ASSESSMENT OF DOSES FROM NORMAL DISCHARGES External exposure 

The assessment of external irradiation from the source is straightforward, at least in principle. When the source is discrete, the radiation fields in its vicinity may be measured (the natural background radiation should be estimated and subtracted from the results) or calculated using simple techniques. To determine the dose to the critical group, calculations should be 

The most exposed group of the population for external exposure in conditions of chronic normal discharges may be represented by persons working mainly outdoors (such as field workers, herders and foresters). If a residential area is located in the vicinity of a nuclear facility, persons hving in one storey houses constructed of light materials (e.g. wood) should be taken into account in the identification of the critical group. 

The calculation of doses from inhalation requires data on the volume of contaminated air inhaled in a year by individuals of the critical groups. This volume will depend on their ages, the proportion of the year that members of the critical group are likely to spend in the area and their activities in the area. The ICRP has provided guidance in this matter [34]. 

When the contamination of foodstuffs and beverages has been assessed by means of models, calculation of the source related doses is straightforward. Modification of the contamination of foodstuffs due to food processing and cooking practices may be taken into account at this stage of the dose calculation, but cautious verification of data is necessary. 

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