[en] European Community (EC) countries realize that their energy demand cannot be met without a nuclear component, which is almost a necessity owing to its major economic advantages. Two typical areas where the Commission has stimulated intense international co-operation are as follows: The first broad area deals with efforts towards a gradual harmonization of regulatory health and safety practices and requirements for reactors of an industrially developed type, more specifically (light) water-cooled reactors. The second area concerns joint research programmes and co-ordination activities in research on nuclear safety (LWRs and LMFBRs). These two broad areas are closely interconnected. Information is also given on the existing network of bilateral and multilateral arrangements for the exchange of information of interest to the EC. In conclusion, some problems are highlighted where improvements could be made or where it seems crucial that increased international co-operation and especially agreement should come about. (author)