Fuel assembly lower portion locking device and locking and unlocking method

Abstract

The invention discloses a fuel assembly lower portion locking device and a locking and unlocking method. The locking device comprises a guide rod which is arranged in a pipe leg of a fuel assembly inan axially reciprocating mode, a driving structure which is arranged at the lower end of the guide rod, a rotating structure which is rotationally arranged in the pipe leg and matched with the drivingstructure, and a blocking rod which is rotationally arranged in the pipe leg and fixed relative to the rotating structure. A through hole is formed in the position, corresponding to the blocking rod,of the pipe wall of the pipe leg. When the guide rod is in a first position in the pipe leg, the blocking rod is located in the pipe leg; when the guide rod is moved from the first position to a second position in the pipe leg, the rotating structure is driven by the driving structure to rotate, the blocking rod is driven to rotate and extend out of the through hole to abut against one side of alower reactor core plate, and the fuel assembly is locked on the lower reactor core plate. The locking device is used for locking the lower portion of the fuel assembly and is simple and reliable in structure and convenient to operate, the locking and unlocking movements and the material replacing movement of the fuel assembly are synchronous, the requirement for a material replacing device is low, and the reliability of the locking device is improved.

Description

technical field [0001] The invention relates to the technical field of reactor fuel assemblies, in particular to a fuel assembly lower locking device and a locking and unlocking method. Background technique [0002] Fast reactor is the most important way to increase the value of nuclear fuel, improve the utilization rate of uranium resources, and reduce long-lived nuclides. At present, most of the liquid fast reactors in the world adopt pool structure. In order to ensure the integrity of the system boundary, the reactor needs to be in a sealed state, and the top cover of the reactor cannot be opened even during the refueling process. Therefore, in such a special environment, the reactor core has no upper core plate in order to meet the requirements of refueling without opening the cover. In order to prevent the fuel assembly from jumping under working conditions such as earthquakes, it is necessary to add a lower locking device to the legs of the lower tube. [0003] The e...

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Problems solved by technology

[0004] 1. The refueling mechanism needs to provide torsional load and precise positioning. The refueling steps are complicated, and the refueling mechanism needs to perform multiple operations on the fuel assembly; 2. The fixed sleeve is subjected to axial force when the fuel assembly is locked. During long-term operation, it is easy to cause the deformation of the fixing sleeve and cause the locking parts to become stuck and cannot be unlocked

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