A Pebble Bed Modular Reactor (“PBMR”) is a small, modular nuclear reactor. The fuel is uranium embedded in tennis size balls made out of graphite. PBMRs have a number of advantages over large traditional reactors. They have much lower capital and operating costs and use an inert gases rather than water as a coolant. Therefore, they do not need the large, complex water cooling systems of conventional reactors and the inert gases do not dissolve and carry contaminants. Second, a PBMR cools naturally when is shut down and this "passive safety" characteristic removes the need for redundant active safety systems. Also, PBMRs operate at higher temperatures which makes more efficient use of fuel and they can directly heat fluids for low pressure gas turbines.
China has an operating prototype, is finishing the first two commercial units and has plans to build a number more. China ultimately plans to build up to 300 gigawatts of reactors and PBMRs are a major part of the strategy. Small, modular reactors are also very attractive to small population centers or large and especially remote industrial applications. Companies such as Hitachi are currently working on turn key solutions.
It is estimated that each PBMR requires 300 tonnes of graphite at start up and 60-100 tonnes per year to operate.
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