LFR systems are Pb or Pb-Bi alloy-cooled reactors with a fast-neutron spectrum and closed fuel cycle. Options include a range of plant ratings, including a long refueling-interval battery ranging from 50-150 MWe, a modular system from 300-400 MWe, and a large monolithic plant at 1200 MWe. 
These options also provide a range of energy products including electricity and hydrogen. The focus of the U.S. R&D in the Generation IV program is on the long refueling-interval battery concept.
The LFR battery option is a small, factory-built turnkey plant operating on a closed fuel cycle with a very long refueling-interval (15 to 20 years) cassette core or replaceable reactor module. Its features are designed to meet market opportunities for electricity production on small grids, and for developing countries that may not wish to deploy an indigenous fuel cycle infrastructure to support their nuclear energy systems. Its small size, reduced cost and full support fuel cycle services can be attractive for these markets.
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