Position-based sampling for eddy current inspection of steam generator tubes

Patent metadata

Field	Value
Publication number	US-10746697-B2
Application number	US-201715810333-A
Country	US
Kind code	B2
Filing date	Nov 13, 2017
Priority date	Mar 29, 2017
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

A method of employing an eddy current sensor to perform an inspection of a tube of a steam generator involves accelerating and decelerating the eddy current sensor in a predetermined fashion that substantially reduces the likelihood of damage to the eddy current sensor. The reduction of probe stresses reduces radiological waste and reduces radiation exposure to workers involved in changing damaged probes The recording of an eddy current signal at each of a plurality of equally spaced apart locations along the tube permits the velocity of the eddy current sensor to be varied without compromising the validity of the data that has been recorded. The inspection system employs an encoder that outputs a series of signals as the probe is advanced incremental distances within the tube of the steam generator, and eddy current sensor signals are recorded responsive to at least some of the signals from the encoder.

First claim

What is claimed is:

1. A method of employing an eddy current sensor to perform an inspection on a tube from among a plurality of tubes of a steam generator of a nuclear installation, the eddy current sensor being structured to output an eddy current signal, the tube having a first straight portion, a second straight portion, and a bend situated between the first and second straight portions, the method comprising:
accelerating the eddy current sensor to be moving at a first velocity within the first straight portion in a direction toward the bend; and
decelerating the eddy current sensor to be moving at a second velocity less that the first velocity within the first straight portion in a direction toward the bend as the eddy current sensor reaches the bend.

2. The method of claim 1 , further comprising moving the eddy current sensor at the second velocity through at least a portion of the bend.

3. The method of claim 2 , further comprising accelerating the eddy current sensor to be moving at a third velocity greater than the second velocity within the second straight portion in a direction away from the bend.

4. The method of claim 3 , further comprising recording at least a portion of the eddy current signal when the eddy current sensor is situated at each of a plurality of equally spaced apart locations along the tube.

5. The method of claim 1 , further comprising recording at least a portion of the eddy current signal when the eddy current sensor is situated at each of a plurality of equally spaced apart locations along the tube.

6. The method of claim 1 , further comprising:
employing a drive mechanism to move the eddy current sensor through at least a portion of each of the first straight portion, the bend, and the second straight portion;
receiving from the drive mechanism a series of outputs that are each representative of the eddy current sensor having been moved a predetermined distance along the tube; and
responsive to at least a subset of the series of outputs, performing the recording.

7. The method of claim 1 wherein the bend has a radius, and further comprising moving the eddy current sensor along the bend from a beginning of the bend adjacent the first straight portion to an end of the bend adjacent the second straight portion according to a velocity profile that includes the second velocity such that the moving of the eddy current sensor from the beginning of the bend to the end of the bend takes a period of time.

8. The method of claim 7 , further comprising performing an inspection on another tube from among the plurality of tubes, the another tube having another first straight portion, another second straight portion, and another bend situated between the another first straight portion and the another second straight portion, the another bend having another radius different than the radius, comprising moving the eddy current sensor along the another bend from a beginning of the another bend adjacent the another first straight portion to an end of the another bend adjacent the another second straight portion such that the moving of the eddy current sensor from the beginning of the another bend to the end of the another bend takes another period of time equal to the period of time.

9. An inspection system usable to perform an inspection of a steam generator that comprises a plurality of tubes, the inspection system comprising:
an eddy current probe comprising an eddy current sensor that is structured to output an eddy current signal;
a drive mechanism that is cooperable with the eddy current probe to move the eddy current sensor with respect to a tube of the plurality of tubes, the drive mechanism comprising an encoder that is structured to generate a series of outputs, each output of the series of outputs being representative of a successive movement of a predetermined distance of the eddy current sensor with respect to the tube;
a computer that is structured to detect the series of outputs and to record the eddy current signal, the computer comprising a processor apparatus that comprises a processor and a storage, the storage having stored therein a number of routines which, when executed on the processor, cause the inspection system to perform operations comprising:
operating the drive mechanism to move the eddy current sensor with respect to the tube;
outputting from the encoder the series of outputs;
employing the computer to detect the series of outputs; and
responsive to each of at least some of the outputs of the series of outputs, triggering the computer to store the eddy current signal;
wherein the tube has a first straight portion, a second straight portion, and a bend situated between the first and second straight portions, and wherein the operations further comprise:
accelerating the eddy current sensor to be moving at a first velocity within the first straight portion in a direction toward the bend; and
decelerating the eddy current sensor to be moving at a second velocity less that the first velocity within the first straight portion in a direction toward the bend as the eddy current sensor reaches the bend.

10. The inspection system of claim 9 wherein the operations further comprise moving the eddy current sensor at the second velocity through at least a portion of the bend.

11. The inspection system of claim 10 wherein the operations further comprise accelerating the eddy current sensor to be moving at a third velocity greater than the second velocity within the second straight portion in a direction away from the bend.

12. The inspection system of claim 11 wherein the operations further comprise recording at least a portion of the eddy current signal when the eddy current sensor is situated at each of a plurality of equally spaced apart locations along the tube.

13. The inspection system of claim 9 wherein the operations further comprise recording at least a portion of the eddy current signal when the eddy current sensor is situated at each of a plurality of equally spaced apart locations along the tube.

14. The inspection system of claim 9 wherein the computer has stored therein a database that comprises dimensional data pertaining to the tube and that further comprises data regarding a plurality of landmarks pertaining to the tube, and wherein the operations further comprise:
determining a distance between a pair of landmarks of the plurality of landmarks;
calculating an expected number of eddy current data samples between the pair of landmarks based at least in part upon the distance and the predetermined distance;
determining from the eddy current signal a detected number of data samples between the pair of landmarks;
determining that the expected number of eddy current data samples and the detected number of data samples are unequal in quantity and, responsive thereto, determining that the number of data samples are unreliable.

Assignees

• Westinghouse Electric Co Llc

Inventors

• Lichauer John C
• Wood Daniel C
• Nenno Thomas W
• Le Qui V
• Flanigan Kyle M

Classifications

• Y02E30/30

  Nuclear fission reactors · CPC title

• G01N27/902 Primary

  by moving the sensors · CPC title

• F22B37/003 Primary

  Maintenance, repairing or inspecting equipment positioned in or via the headers · CPC title

• G01N27/908

  synchronously with scanning · CPC title

• G01N27/9046 Primary

  by analysing electrical signals · CPC title