Began studying physics at Bremen University in 1976. Professional experience: 1981 - 1982 worked on the risk analysis of the SNR-300 by order of the Study Commission on "Future Nuclear Energy Policy" of the German Bundestag. Graduated in 1984. In the same year, foundation of the civil law association Kollert & Donderer, renamed Physikerbüro Bremen in 1996. 1989 - 1993 work as authorised expert according to Section 20 AtG for the states of North Rhine-Westphalia (SNR 300) and Lower Saxony. 1993 - 1995 i.a. EU Tacis project, in co-operation with Bremen University and the Russian Kurchatov Institute, on the neutron-physical design of the RBMK reactor core. 1994 - 1995 work as authorised expert according to Section 20 AtG for the state of Baden-Württemberg. 1996 - 1997 i.a. Tacis projects (RBMK reactors). 1998 - 1999 various activities as authorised expert according to Section 20 AtG for the state of Schleswig-Holstein, focusing on the analysis of design basis accidents and severe accidents.