The project consist of an investigation performed on two reactor types: the pebble bed High-Temperature Gas-Cooled Reactor (HTGR) and Molten Salt Reactor (MSR) with the main focus being on the HTGR. As a first task, the project produced an extensive literature study on the current status of the technology and research on the HTGR and MSR. Secondly, based on the findings from the literature survey, several topics of particular interest have been chosen for more thorough investigations. On the pebble bed HTGRs, the areas of investigation include a preliminary risk assessment study, economic assessment of a modern HTGR, investigation of accident scenarios, and preliminary study on reduction of waste volumes. For both HTGR and MSR an analysis and optimization of the fuel cycle is under way. At the end of the project, based on the literature survey and the results from the scoping studies, future research needs and areas of special interest will be identified for successive projects related to HTGR and MSR in PSI.