The regulatory pyramid is the structure that represents the hierarchy of the regulatory system (Fig. 4.1). The regulations and guides are based on and suit the legal system of the State concerned and establish the principles, requirements and associated criteria for safety upon which the regulatory judgements, decisions and actions are based. The legislative and govern­mental mechanisms ensure that such regulations are developed and approved in accordance with appropriate time scales.

The regulatory pyramid is composed of laws and decrees, regulations, regulatory requirements, safety goals and criteria, safety guides and indus­trial standards. In the development of the regulatory pyramid it is always necessary to take into account the fact that the licensee or operator has the prime responsibility for safety during all phases of the nuclear power plant’s life: ensuring safety in the siting, design, construction, commissioning,

operation and decommissioning phases until the operator is released from the regulatory control of the plant. Therefore, it is important that the regula­tor clearly states that compliance with the conditions, regulations or require­ments imposed by the regulatory body does not relieve the operator of its prime responsibility for safety. The licensee needs to demonstrate to the satisfaction of the regulatory body that this responsibility has been and will continue to be discharged.