When decommissioning and operating nuclear power plants, a lot of radioactive waste in concentrated waste powder, slurry, sludge, and powder is generated. The radioactive waste, non-conformity for disposal, cannot be treated or disposed of, but is currently being stored instead. To dispose of the waste, the waste can be solidified by mixing with an appropriate solidification agent. However, when the solidification agent and powder particles are mixed as in the conventional method, the final volume of the waste form to be disposed of increases. In order to solve this problem, in this study, volume reduction was achieved, compared to the existing powder, by applying the roll compaction technology to mold the radioactive waste into compressed pellets. Soil, concrete, concentrate waste, and contaminated soil powder were used as test materials, and pellets were prepared under different operating conditions. Subsequently, a compressive strength test was performed to confirm the integrity and optimal process conditions of the manufactured pellets. However, in order to perform the compressive strength test, the upper and lower surfaces of the pellets must be horizontal, but the pellet has the shape of two tetrahedrons joined together. Hence, test specimens for measuring compressive strength were prepared by making a surface treatment jig. The compressive strength test showed a high strength of 5.20~28.20 MPa. The process conditions showing high compressive strengths were selected as the optimal process conditions. Finally, the volume reduction ratios were calculated by measuring the weight, density and volume of the manufactured pellets. The degrees of volume reduction of the manufactured pellets compared to the existing powder were checked. When the roll gap was 0 mm, the average reduction ratios of the test materials were 3.7 for the soil, 4.0 for the concrete, 4.6 for the concentrate waste, and 3.8 for the contaminated soil. When roll gap was 1 mm, the ratios were 2.7 for the soil, 2.9 for the concrete, 3.4 for the concentrate waste, and 2.8 for the contaminated soil. Therefore, from a conservative point of view (Roll gap = 1 mm), when powdered waste is formed into pellets, it means that the volume is reduced by 1/2.7 for soil, 1/2.9 for concrete, 1/3.4 for concentrated waste, and 1/2.8 for contaminated soil.

처분 부적합 폐기물이란 원전운영이나 해체 시 처리, 고화 및 포장이 요구되는 방사성폐기물 등을 일컬으며, 대표적으로 분산 특성을 갖는 입자성 방사성폐기물을 예로 들 수가 있다. 이들 폐기물에는 원전 운영과정에서 발생되는 농축폐액의 건조 분말, 슬러리 및 슬러지, 향후 원전 해체과정에서 발생되는 온갖 분말 상태의 폐기물(콘크리트 파쇄물, 제염 슬러지 등), 그리고 제염이 용이치 못한 미세 크기의 방사능오염 토양 등이 있다. 입자성 폐기물을 기존의 고화방식으로 처리할 경우에는 최종 폐기물의 부피가 증가하는 단점을 갖게 되어 처분 비용의 증가 및 처분장의 수용성을 감소하는 결과를 야기할 수가 있 다. 따라서 이들 문제를 해결하고자 본 연구에서는 최종 폐기물 부피의 감용화를 위해 롤 압축 기술을 이용하여 분말의 펠렛화 연구를 수행하였다.