Technology Development of Irradiated Graphite Waste Treatment for the Decommissioning of Research Reactor in KAERI

摘要

In Korea, the irradiated graphite waste is arising from the decommissioning of Korean Research Reactor 2rn(KRR-2). At the KRR-2 nuclear graphite was used as moderator in thermal column that was a space to irradiaternexperimental specimen. The graphite waste has different characteristics than other decommissioning waste due to itsrnphysical and chemical properties and also because of the presence of tritium and carbon-14. The radiological and physicalrnproperties of graphite waste from the decommissioning of KRR-2 were investigated to analyze irradiation effect. Thernirradiated graphite waste retain substantial amounts of Wigner energy and thus to support their packaging, storage andrnultimate disposal, it is necessary to induce the release of the Wigner energy. The annealing condition was investigated torntreat irradiated graphite waste from KRR-2. The Winger energy was released about 80% and 90% until the graphite wasrnheated to 350 °C and 400 °C respectively. And the destruction characteristics of graphite waste were investigated at variousrnthermal conditions. Tested graphite was not easily destroyed in the oxygen-deficient condition. However, the oxidationrnreaction was found to be very effective in the presence of oxygen. No significant amount of the products of incompleterncombustion was formed even in the limited oxygen concentration of 4% O_2. It could therefore be positively said that therndirect incineration would be very effective to reduce the volume of nuclear graphite waste.