Method for servicing a steam generator

Claim 3

The method of claim 1 wherein said first and second preselected distances equal said first and second nominal distances respectively whereby each hole in each row is probed.

Claim 4

The method of claim 1 wherein said first preselected distance equals a first multiple of said first nominal distance and wherein said second preselected distance equals a second multiple of said second nominal distance and wherein the precise location of the skipped holes is determined by electrically summing multiples of the first nominal distance with the column coordinate of the nearest probed hole to determine the column coordinates of the skipped holes and electrically summing multiples of the second nominal distance with the row coordinates of the nearest probed hole to determine the row coordinates.

Claim 5

The method of claim 1 including the steps of: inserting a tool in said carriage; generating signals from the stored signals representative of the precise location of each said hole to sequentially position said arm and carriage to align said tool with the precise location of a plurality of said holes; and generating signals to operate the tool to perform a preset operation at said plurality of holes.

Claim 6

Apparatus for mapping the precise location of holes in a semicircular substantially planar tubesheet of a steam generator wherein said holes are arranged in rows and columns with a first nominal distance between centers along rows and a second nominal distance between centers on columns, said apparatus comprising: an elongated arm pivotally mounted for rotation about one end thereof in a plane parallel to said tubesheet; first servomeans for adjusting the angular position of the arm as a function of an electrical signal; a carriage movable longitudinally along said elongated arm; second servomeans for adjusting the position of the carriage along the arm as a function of an electrical signal; a probe mounted on said carriage generating signals representative of the proximity of the probe to the sides of a hole in the tubesheet in two orthogonal axes parallel to the tubesheet; control means for generating electrical signals to adjust the angular position of the arm and to position the carriage along the arm to generally align the probe with one of said holes, to adjust the angular position of the arm and the position of the carriage along the arm in response to signals generated by the probe to precisely locate the center of the hole, to store the precise location of the hole as a function of the adjusted angular position of the arm and location of the carriage along the arm, to successively reposition the arm and carriage to move the probe a first preselected distance in a direction parallel to the row and similarly locate and store the precise location of the holes at said preselected distances in the row and to then reposition the arm and carriage a second preselected distance in a direction perpendicular to the row to generally align the probe with a hole in another row and to similarly precisely locate and store the precise location of each hole in the tubesheet spaced at said preselected distances.

Claim 7

Apparatus for mapping the precise location of holes in a semicircular substantially planar tubesheet of a steam generator wherein said holes are arranged in rows and columns with a first nominal distance between centers along rows and a second nominal distance between centers on columns, said apparatus comprising: an elongated arm pivotally mounted for rotation about one end thereof in a plane parallel to said tubesheet; first servomeans for adjusting the angular position of the arm as a function of an electrical signal; a carriage movable longitudinally along said elongated arm; second servomeans for adjusting the position of the carriage along the arm as a function of an electrical signal; a probe mounted on said carriage generating signals representative of the proximity of the probe to the sides of a hole in the tubesheet in two orthogonal axes parallel to the tubesheet; control means for generating electrical signals to adjust the angular position of the arm and to position the carriage along the arm to generally align the probe with one of said holes, to adjust the angular position of the arm and the position of the carriage along the arm in response to signals generated by the probe to precisely locate the center of the hole, to store the precise location of the hole as a function of the adjusted angular position of the arm and location of the carriage along the arm, to successively reposition the arm and carriage to move the probe a first preselected distance in a direction parallel to the row and similarly locate and store the precise location of the holes at said preselected distances in the row and to then reposition the arm and carriage a second preselected distance in a direction perpendicular to the row to generally align the probe with a hole in another row and to similarly precisely locate and store the precise location of each hole in the tubesheet spaced at said preselected distances.

Claim 8

The apparatus of claim 5 wherein said first and second preselected distances equal said first and second nominal distances respectively whereby each hole in the tubesheet is probed.

Claim 9

The apparatus of claim 5 wherein said first preselected distance equals a first multiple of said first nominal distance and said second preselected distance equals a second multiple of the second nominal distance and wherein the control means includes means to determine the precise location of skipped holes by electrically summing multiples of the first nominal distance with the column coordinate of the nearest probed hole to determine the column coordinates of the skipped holes and electrically summing multiples of the second nominal distance with the row coordinate of the nearest probed hole to determine the row coordinates.