This progress can be achieved in two main areas:

• the reactor material status: barring exceptions, the safety improvements affecting equipment are reviewed and implemented during the ten-yearly periodic safety reviews rather than as and when they are conceived, to ensure that the facility is not constantly under modification, which could only be prejudicial to safety;
• the working of the organisations involved in the design, construction or operation of the reactor: they can be the subject of a more continual improvement process.

This policy implies the coexistence of facilities with differing levels of safety, with the safety of the older units being upgraded to keep pace with the more recent ones.

Research is also one source of progress in nuclear safety and radiation protection area.

Supervision of "organisational and human factors" (OHF) in a high-risk system such as a nuclear power plant, implies taking into account anything that could help ensure that human intervention on the system is as effective and safe as possible.

Human intervention must be considered at several levels: first of all that of the individual performing a given task (drafting an operating procedure, testing correct operation of a PCB, closing a valve, and so on), or taking a decision. The second level is a collective one (small group, shift team, workshop, etc.), comprising all the individuals concerned by the task (the I&C specialist, his colleague who helps him and the operator who checks the information in the control room). The next higher level is that of the organisational set-up (departments, divisions, units, etc.).

For too long considered to be the weak link and the error-prone cause of technical system failures, man is an essential component of the safety chain, primarily through his ability to adapt, question and react to unexpected situations. His role in running, supervising and maintaining the facilities is vital.

A number of factors determine human performance and thus the ability of the staff to perform their functions efficiently and safely: characteristics linked to human capabilities and limits, skills, working of the groups and the organisations, operating procedures and instructions, quality of the man-machine interface on the technical equipment in the facility and the working tools, constraints inherent in the working environment.

Including organisational and human factors in safety therefore requires consistent action in a number of areas, such as the training and skills of the staff working in the facilities, the ergonomics of the facilities and the operating documentation, individual and group working methods, organisation and management.

The action of the ASN is therefore based on the following general principles:

• the responsibility of the licensee: within the framework of general safety objectives, it is the role of the licensee to define organisational provisions and then adapt them whenever necessary, to take the necessary steps for incorporating human factors into the design and operation of the systems and to ensure adequate training of its staff. The ASN where appropriate analyses and approves certain provisions but prescribes no standardised organisational arrangements for nuclear licensees. Similarly, it is up to the licensee to train its staff and assess their ability to perform their duties;