The AVR (HTGR) Decommissioning Project With New Strategy

The 15-MWel prototype pilot reactor AVR is a pebble bed HTGR. It was designed in the late 50s and was connected to the grid end of 1967. After 21y of successful operation the reactor was shut down end of 1988. In 1994 the first decommissioning license was granted and work with defueling, dismantling and preparation of a Safe Enclosure started. The primary system is contaminated with the fission products Sr90 and Cs137 and the activation products are Co60, C14 and H3. Due to the large amounts of Sr and Cs bound to graphite dust, the dismantling of systems connected to the pressure vessel is very tedious. In 2003 the AVR company was restructured and the strategy of the decommissioning was changed from safe enclosure to green field, i.e. the complete direct dismantling of all facilities and clean up of the site. The highlight during the dismantling is the removal of the reactor vessel (diameter ca. 7.6m and length ca. 26m) in one piece. Before handling the reactor vessel it will be filled with low density cellular concrete. Subsequently the reactor building will be cut open and the reactor vessel (total weight ca. 2100Mg) lifted out and transported to an interim store.