This annual report gives informations on OECD Nuclear Energy Agency activities in 1991. This report is divided into ten chapters: 1 Trends in nuclear power. 2 Nuclear development and the fuel cycle. 3 Nuclear safety and regulation. 4 Radiation protection. 5 Radioactive waste management and disposal. 6 Nuclear science: Reactor physics, nuclear data, NEA data bank. 7 Joint projects and coordinated research programs. 8 Legal affairs. 9 informations programs. 10 relations with non-member countries.