PBMR-A Future Failsafe Gas Turbine Nuclear Power Plant?

This article presents an overview of a pebble bed modular reactor (PBMR) power plant. A PBMR power plant is a gas turbine nuclear power plant that completely eliminates the possibility of a devastating loss-of-coolant accident. In a PBMR power plant, uranium dioxide nuclear fuel, coated with mass diffusion and radioactive fission product containment layers of pyrolytic carbon and silicon carbide, is formed into nuclear poppy seed-sized fuel particles. Some 15,000 of these are embedded in a tennis ball-sized graphite sphere, which is encased in a thin carbon shell, sintered, annealed and machined to a uniformed diameter of 6 cm. The PBMR reactor vessel, 90 ft high and 20 ft wide, is packed with about 450,000 heat-producing nuclear pebbles. Helium gas coolant then flows around and between the pebbles stacked in the reactor vessel, emerging at about 900°F. The Chinese are currently building two pebble reactors that will be used to generate steam for a conventional Rankine cycle.