[en] According to the KRR-1 and 2 decommissioning project, the KRR-2 bio-shielding concrete was dismantled. Total 1,913 tons of concrete, which both activated and non-activated concrete was raised than the estimation as volume of 650 m³ from the size of 9.7 m (W) x17.4 m (L) x 7.8 m (H). The density of the normal concrete is around 2.4 Ton/m³ and it's of heavy concrete is around 3.0 Ton/m³. Before the main activities, the radiation characterization was evaluated for making the mapping between the activated and non-activated concrete. For dismantling, the technologies of the core boring, diamond wire sawing and hydraulic crushing were applied. During 6 months, total 1,964 man-days were consumed. Among the dismantled waste, only 13.2 % of concrete waste was classified as radioactive waste than which were temporally store in the KRR-2 reactor hall as of 38 EA, 4m³ containers and 59 EA. 200 liter drums