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.