South Africa, Japan, China and a consortium of US, Russia, France and Japan are developing small gas-cooled reactor designs and technologies. Coated fuel particles are used in these reactors and they retain fission gases even under accident conditions. Modularization, inherent safety characteristics, direct cycle, and high temperature applications have generated renewed interest in High Temperature Gas — cooled Reactors (HTGR). Japan and China have made the most recent progress in the technology development as they have already constructed and are operating two research reactors; South Africa and the above-mentioned consortium are developing innovative power reactor designs with direct cycle gas turbine for power conversion.

China: The 10 MWe helium-cooled, pebble bed reactor (HTR-10) reached criticality in December 2000. It will initially have steam turbine for phase 1 and later helium turbine for phase 2. Preliminary design of the helium turbine is in progress. It will deliver He at 950 C for electricity generation and for heat applications for coal gasification/liquefaction.

Japan: A High Temperature Engineering Test Reactor (HTTR) with prismatic fuel elements has reached full power this year. This 30 MWth reactor will be the first of its kind to be connected to a high temperature process heat utilization system with an outlet temperature of 850 C. The system will operate as a test and irradiation facility, and be utilized to establish the basic technology for advanced HTGR designs for nuclear process heat applications.

Russian Federation: MINATOM, General Atomics, Framatome and Fuji Electric have combined their efforts to develop the Gas Turbine Modular Helium

Reactor (GT-MHR). This plant features a 600 MW(th) helium cooled reactor as the energy source coupled to a closed cycle gas turbine power conversion system. This is under consideration for the purposes of burning weapon grade plutonium and for commercial deployment. The net efficiency of this advanced nuclear power concept is expected to be 47%. Substantial progress in the development of components such as magnetic bearings and fin-plate recuperators makes this type of HTGR plant a feasible alternative for commercial production of electricity.

South Africa: S. Africa is developing a Pebble Bed Modular Reactor (PBMR) based on technology developed in Germany. The design is a single loop direct gas cycle system that utilizes a helium cooled and graphite-moderated nuclear core as a heat source. The coolant gas transfers heat from the core directly to the power conversion system consisting of gas turbo-machinery, a generator, gas coolers and heat exchangers. The reactor has a thermal power of 268 MW with an electrical output of 110 MW. Improvements of the design are underway to increase the electrical output. The inlet and outlet Helium coolant temperatures are approximately 500 °C and 900 °С, respectively. The important design feature of PBMR is its tennis ball sized pebbles containing the silicon carbide coated HTGR fuel particles, which is expected to contain all fission products for the PBMR13 during all accident conditions, and hence requires no separate containment building.