Following the ASN's decision of 10 November 2000 aiming to improve the conditions for interim storage of very low level (VLL) waste in nuclear power plants, all the plants commissioned VLL waste interim storage facilities.

The nuclear auxiliary buildings (BAN), the waste auxiliary buildings (BAC) and the effluent treatment buildings (BTE) in the nuclear power plants house most of the operations associated with reactor operation and maintenance waste management operations.

Observations in recent years tended to show that the safety of waste management in the BAN, BAC and BTE buildings was unsatisfactory, in particular with regard to containment, fire protection and radiation protection. At the end of 2002, EDF was asked to correct this situation.

The ASN has begun to review the studies forwarded by EDF for eventual improvements in the design and operation of the waste interim storage and treatment buildings in the nuclear power plants. EDF also carried out work to improve these buildings in 2004. The safety analyses concerning these buildings however show inadequacies in the risk assessment owing to the lack of any precise reference system describing the operating range of the waste collection, treatment or interim storage activities in these buildings.

Finally, the series of inspections conducted by the ASN in 2005 on subjects concerning waste management in the nuclear power plants showed that the licensee was aware that improvements to waste management were really necessary and demanded close supervision of both the installations and the quantities of waste held. The actual situation brought to light by these inspections in fact showed that the operating conditions often led to sometimes serious congestion of the installations, for example owing to the problems the sites were encountering in evacuating the waste (malfunction of certain compacting presses, production of nonconforming packages, clearance of the existing stocks). The lessons learned from these inspections will be reviewd by the ASN, in particular with regard to practices in this area, and will guide subsequent monitoring actions.

Some of the energy produced by nuclear power plants is discharged into watercourses or into the sea via a cooling system.

The energy evacuated in the form of heat is discharged either directly into the environment or, for some nuclear power plants located along a river, after cooling in air cooling towers. This latter device is a means of evacuating some of the heat into the atmosphere, thereby reducing the thermal discharges into the rivers.

Owing to its chemical and biological properties, surface water can be propitious to fouling of systems and in particular lead to the formation of deposits and the growth of biofilms. These latter are an ideal medium for the development of micro-organisms such as amoebae and legionella in the cooling systems. Particular precautions must therefore be taken to prevent these micro-organisms from being dispersed into the environment.

The issue of the development of micro-organisms in the systems of power plants with cooling towers has been studied by EDF for a number of years now. It is the subject of periodic exchanges on the basis of EDF studies particularly with the Directorate General for Health (DGS) and the ASN, and is periodically reviewed during the sessions of the French high public health council (CSHPF).