Status of the very high temperature reactor system

The purpose of this paper is to provide an update on the international effort in the development of the Very High Temperature Reactor system pursued through international collaboration in the Generation IV International Forum (GIF) and an outlook for further activities. The initial motivations to develop this reactor type are recalled, a historical overview is given about technology developments and test reactors since 1945 and several of the targeted non-electric applications of VHTR power are addressed. Cooperation in the frame of GIF is clearly beneficial for all project partners. Initially, a wealth of historical experience was collected and shared in the form of documents, dedicated workshops or fuel and material samples. This exchange included properties data, fabrication, irradiation and post-irradiation testing methods, quality assurance, design and analysis tools and methods, as well as the experience in building and operating related equipment. In the further course of the project execution, time, effort and scarce facilities (such as irradiation space or hot cell equipment) are shared, they accelerate progress and create synergies. Recent highlights from currently active GIF VHTR R&D projects (Materials, Fuel and Fuel Cycle, Hydrogen Production) are then provided and placed into the context of the GIF VHTR signatories' national programs. The majority of these currently focus on licensing requirements for demonstrators of near term process steam production scenarios while more aggressive, longer term and higher temperature applications are mainly pursued to enable thermochemical production of bulk hydrogen. Based on the VHTR's high technology readiness level, orientations for future R&D are outlined which would contribute to enhancing the system's market readiness level. These include work on System Integration and Assessment, Safety Analysis and Demonstration, Waste Minimization and Cost Reductions. The inherent safety characteristics of the VHTR are a precious asset for it to become a strong response to today's concerns of nuclear safety, energy security and climate change. •GIF VHTR projects advance international R&D on High Temperature Gas-cooled Reactors.•The VHTR excels in safety, provides energy security and helps mitigate climate change.•Considerable progress in material and fuel development, as well as in H2 production.•New objectives in system integration, safety analysis, waste minimization, economics.•Two test reactors in Japan and Ch