Abstract:  The control rod drive mechanism (CRDM) and the pressure vessel tube seat were usually connected by a welding connection. Aiming at the problems such as the inconvenient to dismantle due to the core change and the deterioration of the seal performance of the secondary welding, the connection of the connection form of the control rod drive mechanism has been researched. A wedge-shaped labyrinth seal structure convenient for maintenance and disassembly was proposed. Firstly, the design concept of labyrinth seal was introduced, the wedge seal structure was also incorporated, and the design of the steel pressure vessel was used to compute the minimum wall thickness required for the control rod actuator mechanism under the working condition and the critical yield temperature under the coupled action of the thermal and compressive loads. Then the finite element was used to simulate the working condition of the C-ring, and the resilience characteristics of the metal C-ring and the state of the seal surface were also investigated. Finally, the wedge labyrinth seal assembly was subject to the leakage rate test and a thermal cycle test of experiments for verification. The results show that the minimum wall thickness under working condition is 10 mm, and the critical yield temperature is 72.5 ℃; the larger the size of the C-ring, the smaller the maximum linear specific pressure value is, and the higher the degree of sealing surface fit; the leakage rate of the wedge labyrinth sealing assembly is less than 1.0×10-6Pa·m3/s, and it can satisfy the sealing requirements of the working condition under multiple disassembly.
Key words:  control rod drive mechanism(CRDM); cuneate labyrinth seal; removable seal construction; sealing performance; leakage rate; minimum wall thickness; critical yield temperature