| 摘要 |
PROBLEM TO BE SOLVED: To insert control rods carefully and properly during emergency shutdown of a reactor with respect to a control rod drive device (2) of the reactor in which a control rod support element (40) in a drive device housing (8) moves between a regular position and an insertion end position, the element is guided within a part by a bush (30) and the bottom (25) of the control rod support element works together with a drive unit (9). SOLUTION: The opening area of a fluid path (42) of pressure fluid passing a squeezing bush is changed according to the actual position of the control rod support element. During emergency shutdown in which the control rod guide element moves with hydraulic pressure of fluid, flow resistance of pressure fluid is varied and especially reduced when the control rod guide element reached the upper insertion end position. As the results, the control rod guide element is braked before reaching the insertion position and mechanical load for braking is reduced. The flow resistance is varied by diameter change in the control rod guide element and the arrangement of by-pass opening (52). COPYRIGHT: (C)2003,JPO
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