Experimental investigation on the volume reduction of irradiated graphite arising from the decommissioning of KRR-2

Graphite has been used as a moderator and reflector of neutrons in more than 100 nuclear power plants as well as many experimental reactors and plutonium production reactors in various countries. Most of the older graphite moderated reactors are already shut down and arc awaiting decommissioning planning and preparation. The graphite waste has different characteristics than other decommissioning waste due to its physical and chemical properties and also because of the presence of tritium and carbon-14. Therefore radioactive graphite dismantling, handling, conditioning and disposal are a common part of the decommissioning activities. A volume reduction of the waste is needed to reduce disposal cost of radioactive waste. However the existing processing technologies are based mostly on the isolation of radioactive graphite from the environment, they are not able to provide for a significant volume reduction. For this reason, the high-temperature thermal treatment process such as an incineration or a pyrolysis is considered as promising technologies, since it provides a substantial volume reduction. Currently, the fluidized bed incineration is considered as efficient technology for the treatment of radioactive graphite waste. In this study, the fluidized bed incineration condition and the radioisotopes behavior were experimentally investigated by using irradiated graphite waste which has arisen from the decommissioning of Korean Research Reactor 2 (KRR-2). (authors)