CONTROL ROD DRIVE DEVICE IN REACTOR

摘要

PROBLEM TO BE SOLVED: To provide a control rod drive device and its reserved reactor shutdown rods for a light water reactor whose output is 100 Mwt or lower. SOLUTION: A mechanism for attaching and detaching a control rod cluster and a control rod drive shaft is replaced with one using a gripper open-close method requiring a complicate mechanism and operation and a permanent magnet which is less degraded even at high temperature is used, whereby the control rod cluster and the control rod drive shaft can be attached and detached by a simple mechanism and operation. By using a material whose magnetic saturation value lowers near at the reactor design temperature for a member attracted by the permanent magnet and shaping the material into a form which is sensitive to the ambient temperature, the control rod cluster can be spontaneously detached when the temperature at an exit of a reactor abnormally rises and reaches the one near the design temperature.