page_title: Generation IV reactor
section_title: Very-high-temperature reactor
hierarchical_section_title: Generation IV reactor / Reactor types / Thermal reactors / Very-high-temperature reactor
context_page_description: Generation IV reactors are a set of nuclear reactor designs currently being researched for commercial applications by the Generation IV International Forum.
  They are motivated by a variety of goals including improved safety, sustainability, efficiency, and cost.
  The most developed Gen IV reactor design, the sodium fast reactor, has received the greatest share of funding over the years with a number of demonstration facilities operated.
  The principal Gen IV aspect of the design relates to the development of a sustainable closed fuel cycle for the reactor.
  The molten-salt reactor, a less developed technology, is considered as potentially having the greatest inherent safety of the six models.
  The very-high-temperature reactor designs operate at much higher temperatures. This allows for high temperature electrolysis for the efficient production of hydrogen and the synthesis of carbon-neutral fuels.
  According to a timeline compiled by the World Nuclear Association, Gen IV reactors might enter commercial operation between 2020 and 2030. However, as at August 2020, no Gen IV projects have advanced significantly beyond the design stage, and several have been abandoned.
context_section_description: The very-high-temperature reactor (VHTR) concept uses a graphite-moderated core with a once-through uranium fuel cycle, using helium or molten salt as a coolant. This reactor design envisions an outlet temperature of 1,000°C. The reactor core can be either a prismatic-block or a pebble bed reactor design. The high temperatures enable applications such as process heat or hydrogen production via the thermochemical sulfur-iodine cycle process.
  The planned construction of the first VHTR, the South African pebble bed modular reactor (PBMR), lost government funding in February 2010. A pronounced increase of costs and concerns about possible unexpected technical problems had discouraged potential investors and customers.
  The Chinese government began construction of a 200-MW high temperature pebble bed reactor in 2012 as a successor to its HTR-10. Also in 2012, as part of the next generation nuclear plant competition, the Idaho National Laboratory approved a design similar to Areva's prismatic block Antares reactor to be deployed as a prototype by 2021.
  X-energy was awarded a five-year $53 million partnership by the United States Department of Energy to advance elements of their reactor development. The Xe-100 is a PBMR that will generate 200-MWt and approximately 76-MWe. The standard Xe-100 four-pack plant generates approximately 300-MWe and will fit on as few as 13 acres. All of the components for the Xe-100 will be road-transportable, and will be installed, rather than constructed, at the project site to streamline construction.
caption: Very-high-temperature reactor