Method and apparatus for handling a tube guide of upper interval equipment of a nuclear reactor

Abstract

The invention relates to a method for handling a nuclear reactor upper internals guide tube ( 15 ), in which method a gripper ( 30 ) equipped, at a first end, with two opposed arms ( 32 ) that can be moved between a retracted position and a deployed position and, a second end, with a control member ( 37 ) for controlling the said arms is introduced into horizontal guide plates ( 24 ) of the upper tube ( 16 ) of the guide tube ( 15 ), the first end of the gripper ( 30 ) is placed under one ( 25 A) of the two upper guide plates of the lower tube, the two arms are deployed, the two arms are applied under this guide plate and the gripper ( 30 ) is used to simultaneously raise the two tubes of the guide tube ( 15 ). The invention also relates to a handling device for implementing this method.

1 . Method for handling a guide tube for the upper internals of a nuclear reactor arranged under water in a pit, the said guide tube comprising two independent tubes, an upper one and a lower one, in each of which there are fixed horizontal guide plates arranged such that they are spaced apart in the axial direction of the guide tube and comprising a central cavity and guide openings for guiding a rod cluster control assembly that controls the reactivity in the core of the reactor, in which method a gripper equipped at a first end with two opposed arms that can be moved between a retracted position and a deployed position and, at a second end, with a control member for controlling the said arms is introduced into the central cavity of the horizontal guide plates of the upper tube, wherein: 
 the first end of the gripper is placed under one of the two upper guide plates of the lower tube,    the arms are deployed by means of the control member,    using the said control member the two arms are applied under the said upper guide plate of the lower tube on the one hand and the second end of the gripper is applied to the upper end of the upper tube on the other hand, and    the gripper is used to simultaneously raise the upper and lower tubes of the guide tube.    
   
   
       2 . Method according to  claim 1 , characterized in that the gripper is rotated about its longitudinal axis into a given position according to marks formed on the upper end of the upper tube when the first end of the gripper is placed under the second upper guide plate of the lower tube.  
   
   
       3 . Device for handling a guide tube for the upper internals of a nuclear reactor arranged under water in a pit, the said guide tube comprising two independent tubes, an upper one and a lower one, in each of which there are fixed horizontal guide plates arranged such that they are spaced apart in the axial direction of the guide tube and comprising a central cavity and guide openings for guiding a rod cluster control assembly that controls the reactivity in the core of the reactor, the said device being formed of a gripper comprising a tubular body equipped at one end with two opposed arms that can be moved between a retracted position and a deployed position and, at a second end, with a control member for controlling the said arms, wherein the length of the tubular body of the gripper is greater than the distance separating the upper end of the upper tube and the first guide plate of the lower tube and less than the distance separating the said upper end and the third guide plate of the said lower tube.  
   
   
       4 . Device according to  claim 3 , wherein the tubular body has, at its second end, a bearing piece for bearing against the upper end of the upper tube, the said bearing piece supporting the said control member.  
   
   
       5 . Device according to  claim 3 , wherein the said control member, first of all, deploys the arms then, secondly, brings these arms closer to the bearing piece.  
   
   
       6 . Device according to  claim 3 , wherein the bearing piece comprises, on its face in contact with the upper end of the upper is tube, at least one elastic washer.  
   
   
       7 . Device according to  claim 3 , wherein the control member comprises a load limiting spring and is connected to the arms by a screw nut system.