Operation and maintenance of the 250 kW TRIGA Mark II reactor at the Jozef Stefan Institute in Ljubljana

Over the last two years the TRIGA Mark II reactor in Ljubljana has been operated at an energy release of about 2500 MWh or about 4100 hour per year. In this period, about 1800 samples were irradiated. In 1983, a new core configuration was established because all Al-clad fuel elements in the core were replaced by the SS-clad elements. The 'J.Stefan' Institute received in 1983, namely, from the TRIGA reactor in Neuherberg, Federal Republic of Germany 107 SS-clad partly burned fuel elements together with some instrumentation which will gradually replace the old radiological and safety instrumentation. The transportation and the dischange of the highly radioactive fuel was done quickly and without any problem. During the last two years the reactor has been operated without any longer shut-down due to technical difficulties. In 1983 we noticed only a fuel element failure during operation. After the short inspection the fuel element with a small clading hole was found and replaced by a new one. (orig.)