| 摘要 |
PURPOSE: To provide a core for a boiled water type reactor wherein unfavorable problems caused by occurrence of dry-out are eliminated. CONSTITUTION: A core for a boiled water type reactor comprises a plurality of vertical fuel assemblies 40a, 42 and 44. Each assembly contains a plurality of fuel rods 10, and the fuel rods are assigned, in a casing 6, between a bottom part connection plate 11 and upper part connection plate 12. They extend, assigned with a space in vertical direction, through a plurality of spacers 13, 13a-13f which holes the fuel rods, together with the connection plates, with a space in lateral direction. Each fuel assembly comprises a bottom part connection plate, a space between fuel rods in a vertical casing, and an inlet 3 for introducing a water through the upper part connection plate. Some fuel assemblies are provided with outlet holes 41, 43 and 44 through which water is released, above the center of the effective length of fuel rod and at least below the top two spacers 13a and 13b, from the space between fuel rods to the outside of the fuel assembly, up to the space in vertical direction where water is present, or, inside the fuel assembly up to a channel 45 in vertical direction where water is present.
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