The proposal is aimed at exploring the use of microbial technologies to reduce risk of contamination from decommissioning of nuclear sites and construction of repositories for nuclear waste. The objective is to reduce the potential for migration of radionuclides (radioactive contaminants) in soils and rocks using special properties of the bacteria that are present in them. The project will investigate two different bacterial properties: (1) How micro-organisms can be used to trap radionuclides within the soil/rock and consequently prevent their transport to the human environment. (2) How some bacteria can be encouraged to produce minerals (e.g. calcite) in soils and rocks that will block any pathways for fluid flow. We will study soils and rocks expected in decommissioning sites and repositories to gain a better understanding of these microbiological properties. The project includes extensive laboratory research (under controlled conditions) and investigations in the field. The processes of mineral deposition and radionuclide capture will be imaged over time and space in three dimensions using complex technologies such as Magnetic Resonance techniques. Computer models will be developed to simulate the basic biological and chemical processes take place. The main findings of the project will directly benefit the nuclear industry and the public; reducing risks from radionuclide migration, and contributing to economical clean-up strategies.