Proryv Project. Assembly of the world’s first lead-cooled fast reactor BREST-OD-300 began with the installation of a 165-tonne steel support plate. This was followed by sinking the first section of the reactor pressure vessel – the lower tier of the RPV protective structure – into the reactor pit. BREST-OD-300 is a 300 MW Generation IV reactor being constructed as part of the pilot demonstration center (ODEK) for the Proryv (Russian for Breakthrough) Project, which is aimed at closing the nuclear fuel cycle. Apart from the reactor, ODEK will include a fabrication facility for uranium-plutonium nitride fuel and a spent fuel processing unit.