The review of the compliance with safety principles, goals and criteria, using the information provided by the licensee, is a critical task. This information needs to be accurate and should be sufficient to demonstrate the safety of the nuclear power plant considering, among other factors, the site interac­tion with the plant, the operational limits, test acceptance criteria for com­missioning, all safety-related features of the design, safety of the operational modes and plant states, and decommissioning aspects.

All plant states (normal operation, anticipated operational occurrences and accident conditions) have to comply with the regulations and safety criteria. Therefore it is essential that the regulatory body defines and makes available to the operator the regulations and criteria and the basis for com­pliance that are to be applied during reviews and on which its judgements and decisions are based.

The regulatory programme for review and assessment includes all stages of the development of the nuclear power plant — from initial selection of the site, through design, construction, commissioning and operation, and including decommissioning until the plant is released from regulatory control. The review also covers deterministic and probabilistic safety analy­sis as needed to verify safety. A set of conservative deterministic rules and requirements for the design and operation of the plant or for the planning and conduct of activities is prepared for anticipated operational occur­rences and postulated accident conditions. The probabilistic safety analysis determines all safety-significant contributors and evaluates the safety balance of the plant. One of the outputs is to verify the probabilistic safety criteria, if they have been defined. Probabilistic approaches provide insights into the reliability of the plant systems, interactions and weaknesses in the design, the application of defence in depth, and risks that it may not be possible to derive from a deterministic analysis.

The regulatory body specifies the time frame for submission of all neces­sary documentation, indicating the period of time that is considered neces­sary for the review and assessment process; this facilitates the process and minimizes delays in granting the license or any other authorization. Usually, the licensee needs to carry out additional work to complete the information for demonstration of safety. In such cases it is very beneficial to monitor the progress of documents by the operator and the progress of the review and assessment process taking into account a tentative schedule agreed by the operator and the regulatory body.

The safety analysis performed by the licensee and the results of regula­tory review and assessment are major relevant inputs to define the regula­tory inspection programme.

In the pre-licensing stage, it is necessary to arrange an early regulatory review and approval of the proposed design safety requirements, for the plant selected and the review of the key features of the design to identify safety issues that would require modifications, development, or additional analysis in order to achieve an initial regulatory approval.