ICNWMT 2019: 21st International Conference on Nuclear Waste Management and Treatment (from 7-8 January, in Tokyo) aims to bring together leading academic scientists, researchers and research scholars to exchange and share their experiences and research results on all aspects of Nuclear Waste Management and Treatment. It also provides a premier interdisciplinary platform for researchers, practitioners and educators to present and discuss the most recent innovations, trends, and concerns as well as practical challenges encountered and solutions adopted in the fields of Nuclear Waste Management and Treatment.