Pebble-bed modular reactor: A generation IV high-temperature gas-cooled reactor

Abstract

Most of the development in nuclear power in the past 30 years has gone into water-cooled reactors. As government funding has dwindled, development of promising alternative systems has lapsed in most countries. Although gas-cooled reactors have had a very good safety record, many have not been able to compete on economic grounds, mainly because of poor operating records and/or high infrastructure costs. Since broad-based construction has not been achieved, gas-cooled reactors have not benefited from cost reductions in the learning curve. The realization that nuclear energy will need to contribute to future power production expansion and the reduction of greenhouse gases has led to the resurgence of interest in safer and more economical ways to produce nuclear energy. One of these alternatives is the high-temperature gas-cooled reactor, as exemplified by the pebble-bed modular reactor (PBMR) being developed in South Africa. This direct-cycle, low power density design is based on clustering modules of modest power output into flexible power plants. Economic targets can be met through simplification by dispensing with the need for extensive back-up safety systems and high plant availability due to on-power refuelling and low-maintenance equipment.