[en] The present report is a comprehensive compilation of the adopted NKS project plans for the sixth four-year period, 1998-2001. Most of the plans are in English. One is in both English and Danish. One is in Norwegian, with a brief summary in English. Only two of the six appendices are in English. In spite of this, it is believed that the report will serve as a valuable source of information not only to those actually active in or closely following the NKS work, but also the international scientific community, e.g., within EU and in the Baltic States. The research program incorporates reactor safety, radioactive waste, emergency preparedness, radioecology, cross-disciplinary studies, and information issues. The necessary administrative support program, including the NKS Secretariat, is not described herein. Neither is the aim, scope or organization of NKS, since this has been covered elsewhere. (EHS)