| 摘要 |
PROBLEM TO BE SOLVED: To provide a reactor core that reduces increase of the output of a fuel assembly when the coolant flow rate in the fuel assembly is increased and can improve the heating margin. SOLUTION: In the core 5A, a plurality of fuel assemblies 10 and 11 are arranged inside the outermost layer area 9. The fuel assemblies 10 are formed in a fuel supporting fitting, and connected to a first coolant passage having a first orifice in its inlet. The fuel assemblies 11 are formed in a fuel supporting fitting, and connected to a second coolant passage having a second orifice in its inlet. The pressure loss of the first orifice is smaller than that of the second orifice. The fuel assemblies 11 are adjacently arranged on four side surfaces of the plurality of fuel assemblies 10. The coolant flow rate of the fuel assemblies 11 is smaller than that of the fuel assemblies 10, and the output of them is lower than that of the fuel assemblies 10. As a result, the coolant flow rate of the fuel assemblies 10 increases, but four fuel assemblies 11 of low output are adjacent to each other and hence the increase rate of the output is suppressed. COPYRIGHT: (C)2009,JPO&INPIT
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