The Jules Horowitz Reactor (JHR) is a reference international user facility to observe and understand material and fuel behaviour in extreme nuclear environment with irradiation loops reproducing the operational condition of the different power reactor technologies. Its primary uses will be research into the performance of nuclear fuel at existing reactors, testing of materials used in reactors, testing designs for fuel for future reactors and the production of radioisotopes used in medicine or industry. JHR is built and will be managed in the framework of an international cooperation between 15 organizations from 11 countries bound by a Consortium Agreement signed on March 2007 . The site preparation for the project began at the Cadarache Research Centre in 2007. The civil works of the main buildings are now completed. And since French State decision, in July 2023, to persue, with the support of nuclear industry, the investment in JHR reactor until completion, the roadmap proposed by CEA can be implemented. This roadmap leads to a start up of the reactor in 2032.