Some aspects of licensing, periodic inspections and backfitting of TRIGA reactors

After a brief historical retrospective view on the early days of TRIGA reactor operation in the light of both technical and legal aspects the considerable changes over the years in reactor safety philosophy and licensing procedure will be discussed. Although an extremely successful operating record has been demonstrated by TRIGA reactors throughout almost three decades, several reactor facilities have been now in operation for more than twenty years. The question, whether to renew obsolete control and instrumentation systems or reactor components will be seen in the light of present days knowledge and technical standards. Upgrading or license renewals require or at least make new credible accident analysis highly desirable. The reason for this and the subjects to be dealt with in this respect will be shown. Caused by changes of research Programs or other reasons the safety report and other documents may be updated occasionally. To what extent does this fact result in a renewal of the licensing procedure? Further points of discussion are practical aspects of the reinspection procedure as well as possible interactions between operation of mixed cores and licensing. Finally some aspects for future work in the above mentioned area will be discussed. (author)