Method and apparatus for permissive control of a mast and grapple

Abstract

A method and apparatus for the permissive control of a mast and fuel grapple to be used in the movement of reactor fuel components, including fuel assemblies, single blade and double blade guides, to be used in a Boiling Water Reactor (BWR) nuclear reactor. The Permissive Control System reduces the chance of human error associated with the movement of reactor components by assisting in controlling the location (plant coordinate) of the mast for picking-up and dropping-off reactor components, the sequence of reactor component movements, the orientation (angular rotation) of the mast and fuel grapple, the raising and lowering of the grapple, and the opening and closing of the fuel grapple.

1 . A mast orientation sensing apparatus, comprising:
 a gimbal plate, the gimbal plate configured to rotate in unison and in response to an angular rotation of a mast with a grapple on an end of the mast;   a cam attached to the gimbal plate, the cam, the gimbal plate, the mast and the grapple configured to rotate bi-directionally and in a same direction with each other;   a plurality of switches positioned in proximity to the gimbal plate, the switches configured to detect a position of the cam;   a controller configured to determine an orientation of the mast and grapple based on the detected position of the came.   
     
     
         2 . The mast orientation apparatus of  claim 1 , wherein the plurality of switches include four switches located at substantially 90 degrees of angular separation from each other. 
     
     
         3 . The mast orientation apparatus of  claim 1 , wherein the switches comprise limit switches, proximity switches, reed switches, or other such switches configured to detect the presence of the cam. 
     
     
         4 . The mast orientation apparatus of  claim 3 , wherein the switches are biased so that only the switch located nearest the cam may indicate the cam position. 
     
     
         5 . A mast orientation system, comprising:
 the mast orientation sensing apparatus of  claim 1 ,   a sensor configured to sense a location of the mast and grapple;   the controller configured to receive the sensed location, the controller configured to prohibit a lowering of the mast and grapple if the sensed location and orientation do not match a requested location and orientation   
     
     
         6 . The system of  claim 5 , further comprising:
 a user interface configured to display the mast and grapple location, orientation, and a grapple position, the grapple position being either opened or closed.   
     
     
         7 . The system of  claim 6 , wherein the controller is further configured to prohibit a changing of the grapple position, from either opened to closed or closed to opened, if the controller detects that the sensed location and orientation of the mast and grapple are not in the requested location and orientation. 
     
     
         8 . The system of  claim 6 , wherein the user interface is configured to allow a user to input the requested locations and orientations, the requested locations and orientations corresponding to pick-up and drop-off locations and orientations of reactor components. 
     
     
         9 . The system of  claim 8 , wherein the user interface is configured to allow a user to input a sequential order of reactor component movements, the sequential order corresponding to the movement of reactor components on a nuclear reactor move-sheet.