| 摘要 |
PROBLEM TO BE SOLVED: To obtain a control rod assembly capable of removing a thermal stress generated on the upper part of a reactor core, and capable of removing a delay of an insertion time at the time of a scrum. SOLUTION: The inner diameter of a guide pipe 1 and the outer diameter of a control rod body 2 are narrowed to such a degree that the pressure between an entrance nozzle 3 and the control rod body 2 becomes higher than those of the outlet part of a guide pipe handling head 4 and the inlet part of the entrance nozzle 3, at the time of rapid insertion when a scrumming operation of the control rod body 2 is executed by a control rod driving mechanism, and a flow rate of a liquid metal coolant flowing between the guide pipe 1 and the control rod body 2 is restricted, and flowing of the liquid metal coolant into the control rod body 2 is accelerated, to thereby enable to reduce the maximum temperature difference between the control rod body 2 and the outlets of a control rod assembly and a fuel assembly.
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