Fuel assembly grid inspection method

• US 4,865,800 A
• Filed: 09/26/1988
• Issued: 09/12/1989
• Est. Priority Date: 06/22/1987
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Field, Michael J., Amhed, Hassan J.
• Primary Examiner(s): Hunt, Brooks H.
• Assistant Examiner(s): WASIL, DANIEL D
• Application Number:
  US07/248,836
• Time in Patent Office: 351 Days
• Field of Search: 376/248, 376/258, 376/260, 376/261
• US Class Current: 376/248
• CPC Class Codes: G21C 17/06 Devices or arrangements for monitoring or testing fuel or fuel elements outside the reactor core, e.g. for burn-up, for contamination G21C17/08, G21C17/10 take precedence; detecting leaking fuel elements during reactor operation G21C17/04
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

A fuel assembly grid inspection apparatus includes a precision noncontact measurement device having a source of illumination and a viewing system which defines an inspection field of view. The viewing system is adapted to view and record one or more images of an object, such as a fuel assembly grid, located in the field of view to provide information from actual measurements of the grid which can be calculated to determine whether or not it comes within acceptable tolerances of the measurements of a standard grid of the same design. The apparatus also includes a universal fixture adapted to support any one of a variety of grids of different designs within the field of view such that portions of the fixture within the field of view are substantially transparent to the viewing system. The viewing system and the fixture are movable relative to each other in X, Y, and X directions for achieving a complete inspection of all parts of the grid. Typically, the grid being inspected has at least a pair of vertically displaced fuel rod contacting dimples disposed in each of a plurality of cells defined in the grid. The dimples are inspected for perpendicularity with respect to each other by using the viewing system to view them at separate instances but from the same location within the field of view.

Claims

1. In a fuel assembly grid inspection method, the combination comprising the steps of:

(a) defining an illuminated inspection field of view;

(b) supporting a fuel assembly grid of a design having known standard measurements within the inspection field of view by using a fixture whose portions which project into the field of view to support the grid therein are substantially transparent to the field of view;

(c) viewing the grid within the field of view; and

(d) recording an image thereof to provide information about the grid from which actual measurements can be calculated and compared to the known standard measurements for the particular grid design.

2. The method as recited in claim 1, wherein said supporting step includes providing a fixture being universally adapted for supporting within the inspection field of view any one of a plurality of fuel assembly grids of different designs having different known standard measurements.

3. The method as recited in claim 1, wherein said viewing step includes:

maintaining a video camera and lens system pointed toward the field of view and the grid supported therein; and

moving at least one of the grid and the video camera and lens system relative to the other for viewing the grid.

4. In a fuel assembly grid inspection method, the combination comprising the steps of:

(a) defining an illuminated inspection field of view;

(b) supporting within the field of view a fuel assembly grid having at least a pair of fuel rod contacting dimples disposed in each cell of a plurality thereof defined in the grid which are adapted to receive fuel rods therethrough;

(c) inspecting the pair of dimples for perpendicularity with respect to one another by viewing the dimples at separate instances from the same location within the field of view; and

(d) recording a separate image of each dimple to provide information from which actual measurements of any offset in X and Y directions of one dimple with the other can be calculated.

5. In a fuel assembly grid inspection method, the combination comprising the steps of:

(a) defining an illuminated inspection field of view;

(b) positioning a fuel assembly grid support fixture about the perimeter of the field of view with portions of the fixture which project into the field of view to support a grid therein being substantially transparent to the field of view;

(c) supporting on the fixture within the field of view a fuel assembly grid of a design having known standard measurements;

(d) sensing the position of the fixture for providing information to determine the correctness thereof before proceeding with inspection of the grid; and

(e) inspecting the grid within the field of view.

6. The method as recited in claim 5, wherein said inspecting step includes:

viewing the grid within the field of view; and

recording at least one image thereof to provide information about the grid from which actual measurements can be calculated and compared to the known standard measurements for the particular grid design.