Ultrasonic phased array transducer for the NDE inspection of the jet pump riser welds and welded attachments

Abstract

An ultrasonic phased array transducer assembly having a single housing in which a plurality of phased array transducer subassemblies are mounted at a skewed angle relative to a leading face of the housing and to each other, with each transducer mounted on composite wedge(s) at different orientations within the housing.

Claims

1. An ultrasonic phased array transducer assembly comprising a single ultrasonic probe housing in which a plurality of phased array transducers, respectively comprised of a plurality of transducer subassemblies, are mounted with at least two of the phased array transducers respectively positioned at a skewed angle relative to a leading face of the probe housing and all of the phased array transducers are mounted at skewed angles to each other, with each of the transducer subassemblies in the respective phased array transducers mounted on a common composite wedge within the housing.

2. The ultrasonic phased array transducer assembly of claim 1 wherein the probe housing includes a contoured face to substantially match a surface of a pipe to be examined.

3. The ultrasonic phased array transducer assembly of claim 2 wherein the pipe is a jet pump riser pipe in a boiling water reactor.

4. The ultrasonic phased array transducer assembly of claim 1 wherein each of the phased array transducers has a conductor with each of the conductors tethered together into a single cable assembly which exits the probe housing at a single port.

5. The ultrasonic phased array transducer assembly of claim 1 wherein the ultrasonic phased array transducer assembly includes at least one mounting hole or feature for gimbal attachments.

6. The ultrasonic phased array transducer assembly of claim 1 wherein the plurality of phased array transducer assemblies comprise three or more phased array transducer assemblies.

7. The ultrasonic phased array transducer assembly of claim 6 wherein the at least two phased array transducer assemblies that are positioned at skewed angles relative to the leading face are mounted at substantially a reciprocal angle to each other.

8. The ultrasonic phased array transducer assembly of claim 7 wherein the third phased array transducer is mounted perpendicular to a weld surface.

9. The ultrasonic phased array transducer assembly of claim 8 wherein the third phased array transducer is mounted between the at least two phased array transducers that are mounted at the skewed angles relative to the leading face.

10. A method of inspecting a jet pump riser pipe in a boiling water nuclear reactor, the reactor having at least one jet pump riser pipe, with each riser pipe having at least one welded attachment such as a riser brace, the method comprising: positioning at least one ultrasonic phased array probe housing adjacent to a surface of the riser pipe wherein a front leading face of the probe assembly is positioned adjacent to a weld to be inspected, the probe housing at least partially enclosing a plurality of phased array transducers respectively comprising a plurality of transducer subassemblies; scanning the jet pump riser pipe with at least one ultrasonic phased array probe so that a scanned range of an ultrasonic beam emitted by the ultrasonic phased array probe comprises an area extending from a weld toe down the pipe and extends from a scan surface down at least partially towards an opposing surface of the pipe; and wherein the ultrasonic phased array probe housing includes at least two independent phased array subassemblies mounted on composite wedges and set at skewed angles relative to each other and to a front leading face of the probe housing, with each of the transducer subassemblies in the respective phased array transducers mounted on a common composite wedge within the housing.

11. A method in accordance with claim 10 wherein the scan has a number of angles and the scanning angles are capable of detecting flaws oriented axially and circumferentially relative to the pipe weld.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A further understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

(2) FIG. 1 is a schematic view of one embodiment of the ultrasonic phased array transducer assembly, including element position, of this invention;

(3) FIG. 2 is a top perspective view of the housing of the transducer assembly of FIG. 1;

(4) FIG. 3 is a perspective view of the housing of the transducer assembly of FIG. 1.

(5) FIG. 4 is a schematic view of the transducer assembly of FIGS. 1, 2 and 3 positioned over a pipe adjacent a weld to be inspected;

(6) FIG. 5 is a rear view of the transducer assembly of FIG. 4 showing the curved face of the transducer housing similarly matching the curvature of the pipe; and

(7) FIG. 6 shows the transducer of FIG. 1 positioned over a weld.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(8) As can be seen in FIGS. 1-6, the phase array transducer assembly 10 of this invention contemplates a single housing 12 containing at least two independent phased array transducers utilized for the ultrasonic inspection of a jet pump riser pipe and associated riser pipe attachment welds in a boiling water reactor. An advantage of a single housing containing multiple phased array transducer subassemblies mounted in different positions and angles, whose outputs are coordinated, but independently controlled, is that such a design would eliminate the need to utilize multiple probes for the detection of various flaws which may differ in their orientation. This invention allows the number of tool reconfigurations, and the number of tools and/or probes required to perform inspections to be minimized. Further, when scanning on a contoured surface such as a pipe 36, the phased array transducer assembly 10 must have a contoured surface 18 to maintain a fixed sound path distance from the transducer elements within each of the subassemblies to the area to be inspected. This requirement further explains the desire to minimize the number of custom transducer housings that are needed to be employed for a weld inspection. In addition, due to the unique placement and orientation of the phased array subassemblies 22, 24, and 26, a compact overall housing 12 can be fabricated which allows maximum access to the weld around adjacent obstructions in the surrounding areas. The housing 12 includes a side wall and an opposing second side wall, an end wall and an opposing face 38. The side walls, the end wall and the face define a housing cavity 28 in which the phased array transducers are mounted.

(9) Phased array transducers contain a row or multiple rows of elements referred to as the phased array subassembly that establish the parameters of the ultrasonic sound beam's steering or sweeping capabilities. Phased array transducer housings typically contain phased array subassemblies that are mounted on individual wedges which classically function in unity with one another to generate the desired beams. A more detailed understanding of the operation of ultrasonic phased array transducers can be found in U.S. Pat. Nos. 4,149,420 and 5,563,346. The novel probe assembly 10 of this invention utilizes phased array subassemblies 22, 24 and 26 mounted on separate wedges 38 positioned at dissimilar orientations within the housing, functioning as independent transducers and is not reliant on a plural wedge combination to generate the desired ultrasonic beams. Alternately, the phased array subassemblies may be mounted on a single piece of material with individual wedge surfaces machined to orient the subassemblies in their proper position.

(10) The independent transducer conductors are tethered together in a joint cable 16 through a single port 14 in the housing 12. The port 14 is located such that it will not impede the face or front of the transducer from positioning at or near the weld toe. The housing 12 may contain shoulder mounts 20 for hardware gimbals on each side such that the face or front 18 of the transducer 10 can be positioned at or near a weld toe. The housing face 18 in contact with the surface of the jet pump piping 36 is a contoured such as to maximize coupling to the piping, as can be seen in FIG. 5.

(11) Each transducer 22, 24 and 26, contained within the housing cavity 28 is fixed on at least one composite wedge 38 such as to generate at least one ultrasonic sound beam. The wedge 38 provides a means to set the transducer array at an angle relative to the inspection surface such that different elements of the array are fixed at different elevations relative to the inspection surface.

(12) The transducer claimed herein has at least two phased array assemblies mounted at a skewed angle from each other and relative to the front leading edge 18 of the transducer housing 12. In one preferred embodiment, the single housing 12 contains three phased array transducers 22, 24 and 26. The center transducer 24 and the corresponding wedge is mounted such that its primary or center ultrasonic beam is directed in a plane perpendicular to the leading edge/face 18 of the housing 12. The two transducers 22 and 26 mounted on the clockwise and counter clockwise side of the centered transducer 24 are positioned inside the housing such that their primary or center ultrasonic beam is directed at an angle skewed from a plane perpendicular to the leading edge/face 18 of the housing 12, where the primary ultrasonic beams face away from each other, oriented approximately ninety degrees apart (at approximately reciprocal angles). Alternative configurations such as two, four, or more independent transducers can be utilized in a single housing 12 and would be considered to be within the concept claimed hereafter. In addition, alternative positions of each array may be utilized such that the array perpendicular to the leading edge/face is not the center array.

(13) FIG. 4 shows the phased array transducer assembly 10 positioned adjacent a weld volume, i.e., the weldment 34 and the heat effected zone 30. The base metal 32 of the pipe 36 is shown on either side of the weld volume. As previously mentioned FIG. 5 shows the face 18 of the transducer assembly 10 being closely matched with the curvature of the pipe 36. FIG. 6 shows the view of the transducer assembly 10, shown in FIG. 1, adjacent the pipe 36.

(14) While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.