Limitation of radiation exposure (normal conditions)

• Pages: 15-20

5. Limitation of radiation exposure (normal conditions)

5.1. Dose limitation system

5.1.1. During normal operating conditions, the exposure from sources or

practices should be restricted by the application of the dose limitation system which

includes justification of the practice, optimisation of radiation protection and

establishment of the annual dose equivalent limits.

5.1.2. (1) Once the competent authority has authorised the introduction of a

practice involving exposure to ionising radiations, the subsequent design, use and

operation should be optimised from the point of view of radiation protection.

(2) The optimisation of radiation protection should be carried out taking

into account the exposure of both workers and the public. If the choice of alternative

safety options used for the protection of workers does not affect the exposure of the

public to an appreciable extent, then optimisation of protection of workers could be

carried out independently.

5.2. Optimisation of radiation protection through design

5.2.1. The optimisation of radiation protection should be implemented from the

very start at the planning, design and construction stages, as a part of the licensing

requirements as appropriate.

5.2.2. The process of optimisation should be appropriate to the specific risks of

the installation, and thus may be simple or complex, depending on the extent of the

risks involved. It should specifically take into account any potential impacts of design

choices on the non-radiological risks present in the installation.

5.2.3. When applicable, optimisation should be based on a quantitative

approach using any decision-making tools appropriate to the situation.1

5.2.4. The competent authority, in the event of differential cost-benefit analysis

being chosen as an input in the decision-making process to determine the optimum

radiation protection level, should recommend and agree on the monetary value or

values attributed to the unit collective dose.

5.2.5. Quantitative optimisation is appropriate at the design stage, involving

protection parameters such as thickness of shielding, ventilation flow rate and

containment of radiation sources.

1 IAEA/ILO/NEA(OECD)/WHO: Basic safety standards for radiation protection, 1982 edition,

op. cit., incorporating the ICRP recommendations (ICRP: "Recommendations of the International

Commission on Radiological Protection", Publication No. 26, in Annals of the ICRP (Oxford, Pergamon

Press), Vol. 1, No. 3, 1977), recommends the method of differential cost-benefit analysis. However, other

decision-aiding methods are by no means excluded, as indicated in ICRP: "Cost-benefit analysis in the

optimization of radiation protection", Publication No. 37, in Annals of the ICRP, Vol. 10, No. 2/3, 1983.

The aggregative methods are the most commonly used. These are based on utility functions, where the

cost-benefit analysis is a special case. Other methods include multi-criteria methods and may also

include simple and qualitative approaches as appropriate.

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