At the Laboratory for Reactor Physics and Systems Behaviour (LRS) of the Paul Scherrer Institute (PSI), a central mission of the STARS project (Safety Research for Transient Analysis for the Reactors in Switzerland) is the development of a comprehensive, state-of-the-art and best-estimate safety analysis methodology. The analytical capabilities established in that framework aim at providing a broad range of expertise related to the safety evaluation of the Swiss nuclear power plants (NPPs). A key requirement is that the employed code system provides the capability to perform at any given time, transient and safety analyses of the plants using as basis, validated 3-D core models up to the latest completed operating cycle. Accordingly, the core analysis models need to be updated and re-qualified after each cycle outage, noting that eventual advances in terms of codes, methods and libraries need also to be integrated in this continuous process. The objective of this paper is to present the core management system CMSYS that is being developed within STARS to ensure that the 3-D core modelling and analyses can be made in an efficient and consistent manner for all the Swiss plants. The overall system architecture as well as the level of accuracy achieved for some of the Swiss 3-D core models is presented in a first part of the paper. Thereafter, the advantages that the system offers in terms of assessing and qualifying new analysis methods are illustrated. Finally, the benefit of the system as a basis for other types of R&D applications requiring realistic and qualified core/fuel data is briefly presented.