Welcome to Bavaria - Germany and to the INTERNATIONAL NUCLEAR SIMULATION SYMPOSIUM AND MATHEMATICAL MODELLING WORKSHOP. A triennial international conference jointly promoted by Control.Data, GRS and SCS, which takes place at Schliersee, a small town near the Alps. The aim of the Symposium is to cover most of the aspects of nuclear modelling and simulation in theory and practice, to promote the exchange of knowledge and experience between different international research groups in this field, and to strengthen the international contact between developers and users of modelling and simulation techniques. On the occasion of the Symposium people of scientific and engineering disciplines will meet to discuss the state-of-the-art and future activities and developments. A large number of contributed papers has been strictly examined and selected by the papers committee to guarantee a high international standard. The book contains the accepted papers which will be presented at the Symposium. The papers have been classified according to the following topics: 1. HARDWARE TOOLS 2. SIMULATION-SOFTWARE-TOOLS 3. PLANT ANALYSER 4. REACTOR CORE 5. NUCLEAR WASTE Authors from 9 countries will meet at the Symposium. They work for Industrial Companies, Universities and the Research and Development Institutes so that a broad spectrum of simulation activities is covered: Theory and application, hardware and software, research and operations. The editor is greatful to the authors for making possible the publication of this book, and especially to WOLFGANG F. WERNEB, for the selection of the papers and the contribution to the success of the Symposium.