Generation IV (Gen IV) reactors are nuclear reactor design technologies that are envisioned as successors of generation III reactors. The Generation IV International Forum (GIF) – an international organization that coordinates the development of generation IV reactors – specifically selected six reactor technologies as candidates for generation IV reactors. The designs target improved safety, sustainability, efficiency, and cost. The first commercial Gen IV plants are not expected before 2040–2050, although the World Nuclear Association in 2015 suggested that some might enter commercial operation before 2030.
Overview
No precise definition of a Generation IV reactor exists. However, the term is intended to refer to nuclear reactor technologies that were under development as of approximately 2000, and whose designs were (at least at that time) believed to represent "the future shape of nuclear energy." The six designs selected at that time were: the gas-cooled fast reactor (GFR), the lead-cooled fast reactor (LFR), the molten salt reactor (MSR), the sodium-cooled fast reactor (SFR), the supercritical-water-cooled reactor (SCWR) and the very high-temperature reactor (VHTR).
The majority of reactors in operation around the world are considered second generation and third generation reactor systems, as the majority of the first generation systems have been retired. Since 2021, China is the first country to operate a demonstration generation-IV reactor, the HTR-PM, of the pebble-bed type. (Meanwhile, Generation V reactors are purely theoretical and are not yet considered feasible.)
The most developed Gen IV reactor design is the sodium fast reactor. It has received the greatest share of funding that supports demonstration facilities. Moir and Teller consider the molten-salt reactor, a less developed technology, as potentially having the greatest inherent safety of the six models.
The very-high-temperature reactor designs operate at much higher temperatures than prior generations. This allows for high temperature electrolysis or for sulfur–iodine cycle for the efficient production of hydrogen and the synthesis of carbon-neutral fuels.
Generation IV International Forum
The Generation IV International Forum (GIF) is an international organization with its stated goal being "the development of concepts for one or more Generation IV systems that can be licensed, constructed, and operated in a manner that will provide a competitively priced and reliable supply of energy ... while satisfactorily addressing nuclear safety, waste, proliferation and public perception concerns." It coordinates the development of GEN IV technologies. It has been instrumental in coordinating research into the six types of Generation IV reactors, and in defining the scope and meaning of the term itself.
As of 2021, active members include: Australia, Canada, China, the European Atomic Energy Community (Euratom), France, Japan, Russia, South Africa, South Korea, Switzerland, the United Kingdom and the United States. Non-active members include Argentina and Brazil.
The Forum was initiated in January 2000 by the Office of Nuclear Energy of the U.S. Department of Energy’s (DOE) "as a co-operative international endeavour seeking to develop the research necessary to test the feasibility and performance of fourth generation nuclear systems, and to make them available for industrial deployment by 2030." It was established in 2001, aiming at availability for industrial deployment by 2030.
In November 2013, a brief overview of the reactor designs and activities by each forum member was made available. An update of the technology roadmap which details R&D objectives for the next decade was published in January 2014.
In May 2019, Terrestrial Energy, the Canadian developer of a molten salt reactor, became the first private company to join GIF.
At the Forum's October 2021 meeting, the Forum members agreed to create a task force on non-electric applications of nuclear heat, including district and industrial heat applications, desalination and large-scale hydrogen production.
Timelines
The GIF Forum has introduced development timelines for each of the six systems. Research and development is divided into three phases: Viability: test basic concepts under relevant conditions; identify and resolve all "potential technical show-stoppers"; Performance: verify and optimise "engineering-scale processes, phenomena and materials capabilities" under prototypical conditions; Demonstration: complete and license the detailed design and carry out construction and operation of prototype or demonstration systems.