Based on the authors' recent investigations, this book describes the application of glassy and polyphase composite materials for nuclear waste immobilisation. It introduces immobilisation issues beginning with a short description of nuclear waste types and compositions. Sources of nuclear waste are described including the nuclear fuel cycle, operational and spent nuclear fuel reprocessing waste streams. The glassy wasteforms currently being used for high-, intermediate- and low level radioactive waste immobilisation are described. Problems related to immobilisation capacity, process efficiency and long-term radionuclide retention are highlighted. Scientific and technical problems in nuclear waste immobilisation are emphasised in particular long-term wasteform stability and durability. Recent developments in advanced nuclear wasteforms are described such as glass composite materials (GCM) with higher versatility and waste loading. New immobilisation approaches and technologies are described including advanced cold crucible induction melting (CCM), self sustaining thermochemical immobilisation (SSI), and in-situ self-sintering in deep underground repositories. Long-term durability tests of nuclear waste glasses are outlined and the role of ion-exchange phase in glass corrosion is described in detail.