Preface

Operations in the nuclear power industry produce a wide variety of radioactive wastes. The predisposal waste management is to produce waste packages suitable for storage, transportation and final disposal. Cementation is a widely applied technique for the conditioning of lowand intermediate-level radioactive wastes. Compared with other solidification techniques, the cementation process is relatively simple and inexpensive. Moreover, calcium silicate cements show many advantages, such as easy supply, compatibility with aqueous wastes, good selfshielding and high alkalinity, which allow to precipitate and thus confine many radionuclides. However, specific issues have still to be addressed, such as the limitation of adverse cement–waste interactions which may affect the quality of the resulting solidified waste form, or the understanding and prediction of long-term properties of the waste packages and cement barriers. There is also a need for safe processes minimizing the production of secondary wastes. Facing these major challenges, the objective of the 1st International Symposium on Cement-Based Materials for Nuclear Wastes (NUWCEM), that was held in Palais des Papes, Avignon and Marcoule Research Center on 11–14 October, 2011, was to promote the exchange of advanced information on the ongoing research and development activities dealing with cementation of nuclear wastes, from elaboration of waste packages to their final disposal and long-term behaviour. This book contains some of the contributions to the NUWCEM Symposium. The invited speakers and the contributions from the participants covered the full range of theoretical, computational, experimental and technological approaches. In addition to the present contribution, there were numerous other excellent contributions to the meeting, but because of the shortage of space, not all of these presentations could be included in this book. The chapters included in this book have been grouped as follows: methods of production of cement–waste forms, physico-chemical processes occurring in cement–waste forms at early age, influence of external and internal factors on long-term properties of cement–waste package and cement barriers and emerging and alternative cementitious systems.