 Wolfgang Kröger studied mechanical engineering, specialized on nuclear technology, at the RWTH Aachen University, completed his doctorate in 1974, also at RWTH Aachen, and his habilitation thesis in 1986, which focused on safety requirements for urban-sited nuclear power plants.He joined the Institute for Nuclear Safety Research at National Research Center Jülich (FZJ, former KFA), Germany, in 1974, led projects on underground siting of nuclear power plants, on application of PSA-methodology to HTGR (High-Temperature Gas-cooled Reactor) and on the development of inherently (super) safe reactors.He became deputy and finally acting director (1987) of that institute before he accepted the call to ETH Zurich and, simultaneously, became also research department head and member of the board of directors at Paul Scherrer Institute (PSI) in 1990.