2   FIELDS OF ACTIVITY INVOLVING RADIOLOGICAL RISKS
The activities involving a risk of exposure to ionising radiation can be grouped into the following categories:
- basic nuclear installations;
- transport of radioactive and fissile materials for civilian use;
- production and use of ionising radiation;
- radioactive waste and contaminated sites;
- TENORM (technologically-enhanced naturally occuring ionising radiation) activities.
  2.1 Basic nuclear installations
2.1.1 Definition

The regulations classify nuclear facilities in various categories corresponding to procedures of various stringency, depending on the scale of the potential hazards. The main permanent nuclear installations, called "Basic Nuclear Installations" (BNIs) are defined by decree 63-1228 of 11 December 1963 which sets the categories:
- nuclear reactors, with the exception of those equipping a means of transport;
- particle accelerators;
- plants for the separation, manufacture or transformation of radioactive substances, in particular nuclear fuel manufacturing plants, spent fuel reprocessing plants or radioactive waste packaging plants;
- facilities designed for the disposal, storage or use of radioactive substances, including waste.

The last three types of facilities are however only covered by BNI regulations when the total quantity or activity level of the radioactive substances exceeds a threshold set, according to the type of facility and the radionuclide concerned, by a joint order of the ministers for the Environment, Industry and Health.

Nuclear facilities which are not considered to be BNIs may be subject to the provisions of book V of the Environment Code (conditions applicable to installations classified on environmental protection grounds (ICPEs)).

The BNI status as at 31 December 2005 is given in appendix B.
2.1.2 The safety of basic nuclear installations
The fundamental principle underpinning the organisational system and the specific regulations applicable to nuclear safety is that of the prime responsibility of the operator. The public authorities see to it that this responsibility is fully assumed, in compliance with the regulatory requirements.
The respective roles of the public authorities and the operator can be summarised as follows:
- the public authorities define the general safety objectives;
- the operator proposes technical procedures for attaining them, and justifies them;
- the public authorities ensure that these procedures are consistent with the goals set;
- the operator implements the approved measures;
- during their inspections, the public authorities check correct implementation of these measures and draw the corresponding conclusions.