- Currently used only in the United Kingdom. International interest in developing high temperature gas cooled reactors (HTGRs) is increasing. - HTGRs can provide efficient and cost-effective electricity and produce high-temperature process heat for industrial applications. - Gas cooled reactors represent about 3% of the total number of reactors in commercial operation worldwide. - The United Kingdom has advanced carbon-dioxide gas cooled reactors that will be phased out around the mid-2020s. - Many countries are interested in and developing advanced HTGRs using helium as a coolant. - HTGRs achieve high fuel utilization rates, operate at high temperatures, and produce process heat for various applications. - Small modular HTGR designs are being considered, relying on inherent safety characteristics instead of active engineered safety systems. - Several countries, including China, Japan, Russia, and the United States, have ongoing HTGR research and development projects. - A commercial demonstration power plant, the pebble bed module reactor, is under construction in China with prospects to generate electricity by 2017.