| 摘要 |
PROBLEM TO BE SOLVED: To provide a control rod guide tube suitable for use in the pressure vessel of pressurized water reactor in which the vibration of a plurality of control rods arranged therein is damped appropriately. SOLUTION: The control rod guide tube 130 comprises a housing 140 surrounding a control rod 80. The housing is provided with an inlet opening 150 facing to a hole 100 made through an upper core plate 90 and a coolant induces a vibration in the control rod when it flows through the hole 100 and the inlet opening 150 and enters into the housing. Since the inlet opening of housing is located higher, by a predetermined distance, than the hole with a gap 155 being provided between, first predetermined part of coolant flows out laterally outward of the gap while detouring the inlet opening. The housing is also provided with holes 175a, 175b for delivering the second part of coolant in the vicinity of inlet opening. Since the first predetermined part of coolant detours the inlet opening and the second part of coolant is delivered through the hole, vibration of control rod is suppressed.
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