Generation IV reactors (Gen IV) are nuclear reactor designs that are envisioned as successors of generation III reactors. The Generation IV International Forum (GIF) is an international organization that coordinates the development of generation IV reactors. GIF selected six reactor technologies as candidates for generation IV reactors: 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 designs target improved safety, sustainability, efficiency, and cost. The first commercial plants are not expected before 2040–2050, although the World Nuclear Association in 2015 suggested that some might enter commercial operation before 2030. 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. The majority of reactors in operation around the world are second generation and third generation reactor systems, as the majority of the first generation systems have been retired. No Generation IV reactors were in operation as of February 2023. Generation V reactors are purely theoretical and are not yet considered feasible. Generation IV International Forum The Generation IV International Forum (GIF) is an international organization with as stated goal "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. 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, iaming at availability for industrial deployment by 2030. As of 2021, active members include: Australia, Canada, China, the European Atomic Energy Community (Euratom), France, Japan, Russia, South Africa, South Korea, Switzerland,