This POSTnote will provide an overview of the design and characteristics of future nuclear reactors. It will focus on Generation 3 and Generation 3+ reactors, which will be the next fleet of nuclear reactors to be deployed. It will outline the UK’s involvement in research into Generation IV reactors (post 2020) and beyond, including nuclear fusion. The POSTnote will also discuss how future reactors differ from today’s designs, and the resulting implications, for example for safety, security, cost and waste production. The POSTnote will also discuss long term fuel options and future technologies for waste disposal.