[en] This paper elaborated for the Swiss Federal Office of Energy (SFOE) presents the synthesis report for 2009 made by the SFOE's program leader on the research program concerning nuclear technology and nuclear safety. Work carried out, knowledge gained and results obtained in the various areas are reported on. These include projects carried out in the Laboratory for Reactor Physics and System Behaviour LRS, the LTH Thermohydraulics Laboratory, the Laboratory for Nuclear Materials LNM, the Laboratory for Final Storage Safety LES and the Laboratory for Energy Systems Analysis LEA of the Paul Scherrer Institute PSI. Work done in 2009 and results obtained are reported on, including research on transients in Swiss reactors, risk and human reliability. Work on the 'Proteus' research reactor is reported on, as is work done on component safety. International co-operation in the area of serious accidents and the disposal of nuclear wastes is reported on. Future concepts for reactors and plant life management are discussed. The energy business in general is also discussed. Finally, national and international co-operation is noted and work to be done in 2010 is reviewed