Chemical aspects on the final disposal of irradiated graphite and aluminium: A literature survey

The Finnish FiR 1 TRIGA Mark II reactor is facing shut-down after more than 50 years of operation. The decommissioning of the reactor is planned to start during fall 2015. The management and final disposal of the decommissioning waste require knowledge about, among other things, the possible waste-related chemical reactions and the effects of such reactions on long-term safety. The above warrants the rationale for the literature survey, which was conducted to collect information on: i) The chemical behaviour of irradiated aluminium and graphite in FiR 1 de-commissioning waste under expected final repository conditions. ii) The international practices concerning the management and final disposal of irradiated aluminium and graphite. iii) The experimental techniques for determining the chemical form (organic or inorganic) of the 14C released from graphite waste. The report describes initially the FiR 1 TRIGA reactor, its associated decommissioning waste and foreseen final disposal conditions. The main part of the report focuses on the chemical behaviour of aluminium and graphite under such conditions. In addition, a few examples are provided concerning available methods for managing irradiated graphitic waste and for measuring the contents of organic and inorganic 14C in irradiated graphite. Finally, the report proposes outlines for some experiments to be conducted at VTT in order to determine the release rates of organic and inorganic 14C from the FiR 1 decommissioning waste.