| 摘要 |
<p>In the fast breeder reactor according to this invention, a medium-pressure plenum (47) and a high-pressure plenum (48) are disposed, in the mentioned order from above in a reactor core (1). Sodium is filled in the medium-(47) and high-pressure (48) plenums. The pressure in the medium-pressure plenum (47) is lower than that in the high-pressure plenum (48). The lower ends of the entrance nozzles (29) of a multiplicity of fuel essemblies (2A, 2B) loaded in the reactor core (1) are supported by a supporting plate (4) which forms a boundary between the medium- (47) and high-pressure (48) plenums. The entrance nozzles (41) of control rod guide pipes (39) disposed among the multiplicity of fuel assemblies (2A, 2B) are also supported by said supporting plate (4). The sodium in the medium-pressure plenum (47) is supplied into each control rod guide pipe (39) through a first opening (44) provided in the lateral surface of the entrance nozzle (41) of each control rod guide pipe (39). The sodium in the high-pressure plenum (48) is supplied into each fuel assembly (2A) from the lower end of the entrance nozzle (29) of each fuel assembly (2A) through a second opening (32) provided piercing through the supporting plate (4). The sodium in the high-pressure plenum (48) is supplied to the medium-pressure plenum (47) through a pressure-reducing orifice (54).</p> |
