Safety goals are usually included in the regulations in compliance with the regulatory approach. In general, they are derived from the safety pillars of the IAEA Safety Standards, in particular the Fundamental Safety Principles. Safety goals may establish quantitative or qualitative criteria. The safety goals for existing reactors may also be applied for new reactors. However, it is important to consider further safety improvements that could be made at the design stage of new reactors so that safety is continuously enhanced.

There is no international consensus regarding quantitative safety goals but the current trend is to have a better balance between the deterministic and probabilistic approaches. However, some regional common approaches are useful in order to reach a global consensus at least in the qualitative way. Improved probabilistic calculations or use of operating experience to define risk magnitudes, on the one hand, and improvement in the evaluation of the consequences in terms of core damage frequency, individual doses or large release magnitudes on the other, provide the necessary relationship to establish quantitative goals.

Qualitative goals using a technology-neutral approach (meaning safety concepts and criteria independent of the type of reactor technology) can be found in the IAEA Safety Standards.

In general there are two approaches to the preparation of regulations: a prescriptive approach or a performance-based approach. The degree of application of either approach in the national regulations depends on the regulatory approach selected when establishing a regulatory framework. However, the development of regulations needs a balance between flexibil­ity (to permit easy adaptation of the regulation to changes in circumstances and/or technology) and the need to include detailed requirements (to facili­tate determination of whether the requirements have been met).

Performance-based regulations primarily specify the safety goals to be achieved rather than prescribe detailed or specific requirements. This means that the way in which the licensee is to meet the regulations is not specified by the regulator. The use of safety goals promotes the continuous safety improvement concept and provides enough flexibility to the licensee for them to determine and apply better approaches to enhance safety. This kind of regulation will not need to be changed as frequently to reflect advances in science and technology. The correct interpretation by the licensee of this type of regulation is essential; therefore it is necessary to elaborate regula­tory guides in some cases to provide additional support. The verification of compliance with this type of regulation requires a high level of expertise.

With prescriptive regulations, the regulator states how safety is to be achieved with clearly defined provisions for each safety-related aspect. These provisions include the means and methods to be used in order to comply with regulatory requirements for achieving an adequate level of safety. In some cases it is easier to verify compliance with this type of regu­lation, but high levels of expertise are necessary for their development.

In summary, a modern regulatory system needs to include both types of regulations, to achieve the appropriate balance between performance-based and prescriptive regulations that takes into account the workload and the skills of the regulatory body’s staff.