JPH07209475A - Device for inspecting remote upper inside structure - Google Patents

Abstract

PURPOSE: To provide an inspecting device for an upper internal structure including a control rod guide structure in a nuclear reactor. CONSTITUTION: The upper internal structure of a nuclear reactor has a support plate provided with a center aperture, in which such elements are installed as a housing support to locate a probe body 12 for inspection in the axial direction, a means 10 supporting a probe for inspection within the housing support and moving the probe vertically and rotating, a transducer 16 for sensing the section shape of radially stretching grooves, and a transducer driving means 18 coupled with the body of the transducer 16 for making the centering adjustment of the probe body 12 in the center aperture. This enables moving the transducer 16 within any one of a plurality of radially stretching grooves outward from the center aperture.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention generally relates to nuclear reactor inspection,
More specifically, it relates to an apparatus for inspecting upper internals, including control rod guide structures, in a nuclear reactor.

[0002]

In nuclear reactors, control rod assemblies are used to control the reactivity of the reactor. The upper internals and control rod guide structure house and guide the control rod assembly as it is raised from the core or lowered into the core. The guide structure is generally formed by one or more horizontally positioned plates above the core. A central vertical aperture and channels through each plate house and guide control rods and control rod assemblies.

Known cobweb assemblies pass through slotted channels as the rod is raised and lowered. The channel through the plate extends radially in relation to the aperture. Each groove is provided with at least one cutout section forming a C-shape or split tube shape within the groove. During normal reactor operation, the control rod assembly is withdrawn from the core. In this position, a relatively short length of control rod extends into the core. The flow of cooling fluid through the upper internals causes the control rod to vibrate against the horizontal plate of the guide structure. This vibration causes wear and / or fatigue of the control rods and horizontal plates, especially in the cutout sections of the in-plate grooves. Substantial wear and / or fatigue of the guide plate
It may adversely affect the normal operation of the control rod. Therefore, it is important to know the extent of wear and / or fatigue within the guide structure as proper furnace control is directly related to proper control rod movement. For example, U.S. Pat. No. 4,
728,488, 4,863,678 and 4,90
See 2,468.

Inspection of this plate presents special problems. The shapes of the radial groove and the central aperture are complex. Also, the need for plate evaluation, radioactive contamination and high radiation levels and precise inspection measurements make close inspection impossible.

[0005]

The present invention directly addresses the aforementioned problems.

[0006]

An inspection apparatus is provided for detecting a cross-sectional shape (profile) of a support plate in an upper internal structure at an interface point with a control rod. The probe body is attached to an outer housing support used to axially position the probe body for inspection of the upper internals support plate. The probe body is provided with upper and lower inflatable bladder sections that center and secure the probe body in the center of the support plate of the upper internals.

Accordingly, it is an object of the present invention to provide an atom having a support plate with a central aperture and a plurality of channels extending outwardly from the central aperture and at least one control rod aperture in communication with each channel. In an inspection apparatus for the upper internals of a furnace, an outer housing support for raising and lowering the probe body in the central aperture, a probe support connected to the probe body, and rotating the probe body It is an object of the present invention to provide an inspection device including a probe support and a rotation driving unit connected to the probe body.

A cross sectional shape transducer senses the cross sectional shape of the radial groove in the support plate and transducer drive means is coupled between the probe body and the transducer for moving the transducer radially in relation to the probe body. Centering means is coupled to the probe body for centering the probe body within the central aperture of the. With the probe body lowered into the central aperture by the outer housing support, the rotary drive means moves the probe body into a rotational position to move the transducer radially into one of the radial channels. It can be actuated to rotate, and the transducer drive means can be actuated to move the transducer radially into and along the one channel and rod aperture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the present invention, its operational advantages and the particular objectives achieved by its use, reference should be made to the accompanying drawings and the descriptive part in which preferred embodiments of the invention are illustrated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 4, an inspection apparatus for a nuclear reactor superstructure 4 guides a probe body upwards and downwards inside an outer housing support numbered 100. Has a bearing 11 or a plurality of bearings 11 for receiving a generally tubular elongated upper probe support, generally designated 10.
The outer housing support 100 serves to hold the probe body 12 and probe support 10 and to position the probe on the upper internals and provide axial positioning via lead screws or other means. The probe body 12 is mounted in rotation on a bearing 13 with respect to the lower end of the probe support 10 for rotation about its longitudinal axis. For rotation, always know the exact rotational position of the probe body,
This is achieved by rotary drive means in the form of a motor 15, a gear reducer 101 and an encoder 14 connected thereto.

A cross sectional transducer 16 is mounted on the probe body 12 for radial movement on the transducer drive means, generally designated by the numeral 18. The transducer 16 measures the cross-sectional shape of the groove as it moves radially along the groove so it can be brought into contact with the surface of the groove (as best seen in FIG. 5). Advantageously, it also includes a pair of opposing arms with strain gauges 102. Transducer drive means 1
8 is pivotally mounted on the transducer 16 and opposite ends pivotally mounted on respective upper and lower follower blocks 20, 22 which are vertically slidably mounted within the probe body 12. It includes a pair of arms 17 having side ends. An upper lead screw 24 is screwed into the upper block 20 and rotated by a transducer drive motor 30 through a suitable shaft coupling and gear reducer. A gearhead 28 connects the shaft of the motor 30 to the second encoder 26 to accurately measure the rotational position of the motor shaft and thus the radial position for the transducer 16.

A lower lead screw is screwed into the lower block 22 and is joined to the upper lead screw 24 by a rotary shaft joint 32. The threads on the lead screws 24 and 25 are related to each other so that the blocks 20 and 22 move in opposite directions to advance or retract the transducer 16 radially as the two lead screws rotate in the same direction. Is the opposite.

Before describing the inspection apparatus illustrated in FIG. 1 in further detail, please refer to FIGS. 4 and 2 which illustrate the environment of the present invention. The upper internal structure of the reactor includes a plurality of horizontally extending support plates 40 (in this case, 16
Vertical structure about 14 feet (4.30 meters) high with a small central aperture 8 on its top surface, including a central aperture 42 with outwardly projecting radially extending channels 44. Is included. Each radial channel 44 is in communication with a vertically extending control rod aperture 46 that houses the control rod 48 shown in FIG. Referring to FIG. 3, the shaded area 45 near the connection between the groove 44 and the aperture 46 is the site of highest probability of wear and / or fatigue due to control rod vibration. This is the most effective area to monitor with the device of the present invention.

In operation, outer housing support 100 includes support plate 40 and channel 44 and transducer 16
To lower the probe body 12 vertically through the central aperture 42. The motor 15 is activated and its rotational position is monitored by the encoder 14 to rotate the transducer 16 in the correct rotational direction to access one of the channels 44. Monitored by encoder 26, motor 30 is then actuated to move the transducer radially outward from probe body 12. The transducer 16 measures the cross-sectional shape, in particular the wear and / or fatigue area of the groove 44. The encoder, motor and transducer are all connected to a computer (not shown) for automatically or manually positioning and moving the transducer in collecting data for each groove profile. A standard cross-sectional shape plot produced by this inspection device is shown in FIG. Although a strain gauge is shown, any other transducer or sensor, such as a contactless ultrasonic transducer, could be used to measure the groove cross-sectional shape.

As can be seen in FIG. 1, the spring 54 is
It is connected between the ejector assembly 52 and the probe body 12. If the probe drive malfunctions while the transducer arm 17 is deployed, the transducer 16 deactivates the air cylinder 50 to release the ejector assembly 52 which moves downward as the spring 54 contracts. Can be quickly pulled back into the probe body 12. Release of the ejector assembly 52 causes the shaft coupling 32 to move to the lead screws 24 and 25.
Will disengage from each other and retract the transducer 16. By this recovery method, the probe can be recovered during the malfunction of the drive mechanism without damaging itself and the upper internals of the reactor.

The probe body 12 is centered within the central aperture 42 by an upper 60 and lower 62 bladder, both wrapped around the probe body 12. Air or other air fluid is supplied to the upper hollow interior of the probe body 12 to inflate the upper bladder 60. Air reaches the channel 66 to expand the bladder 60 outwardly and center the upper portion of the probe against the inner wall of the central aperture 42. In a similar manner, capillaries 105 are provided for supplying air or other air fluid to the T-shaped channel 70 in the lower portion of the probe body 12 which inflates the lower bladder 62. Thin tube 68
Supplies the holding air to the air cylinder 50 so that the pressure loss inside the probe body 12 retracts the transducer.

The cap 72 has a rounded outer surface to facilitate entry of the inspection device into the upper internals. The probe body 12 is sealed above and below the area of the transducer 16 and the probe body 12 is provided with a longitudinal slot 74 to allow the transducer 16 and its arms 17 to be radially deployed and retracted. Along with it, it has a cylindrical shape. Thus, the probe body is sealed in all areas except the transducer 16 area.

[Brief description of drawings]

1 is a composite longitudinal cross-sectional view of a probe device according to the present invention.

FIG. 2 is a top view of a support plate for upper internals for a nuclear reactor.

FIG. 3 is a partial top view of the control rod aperture and connecting channel to be inspected in accordance with the present invention.

FIG. 4 is a composite vertical cross-sectional view of the entire inspection apparatus positioned on the upper internal structure.

FIG. 5 is an enlarged view of a transducer with an inspection arm equipped with strain gauges.

FIG. 6 is a standard cross sectional shape plot generated by inspection.

[Explanation of symbols]

 10 Probe Support 12 Probe Body 16 Cross Section Transducer 17 Transducer Arm 18 Transducer Drive Means 20, 22 Follower Block 42 Central Aperture 44 Radial Groove 46 Control Rod Aperture 60 Inflatable Bladder 100 Outer Housing Support

Claims (3)

[Claims] 1. A central aperture (42) and a plurality of radial grooves (4) extending outwardly from the central aperture.
4) and a support plate (40) with at least one control rod aperture (46) in communication with each channel, in an apparatus for inspection of a reactor upper internals, in a central aperture Outer housing support (1) for raising and lowering the probe body (12)
00), a probe support (10) connected to the probe body (12), a rotary drive means connected to the probe support, and a cross-sectional shape transducer for detecting the cross-sectional shape of the radial groove in the support plate. (16) and transducer drive means (18) coupled to the probe body (12) for centering the probe body within the central aperture, the probe body being lowered into the central aperture by the outer housing support (100). And the rotary drive is operable to rotate the probe body into a rotational position to move the transducer radially into one of the radial channels, and the transducer drive means (18).
Is operable to move the transducer radially into and along the groove and into the communication area between the groove and the control rod aperture. Inspection device. 2. A centering means comprising an upper inflatable bladder (60) connected to the probe body (12) above the transducer and a lower inflatable bladder connected to the probe body below the transducer. 1. The device according to 1. 3. A pair of follower blocks (20,22) slidably mounted to the probe body, the transducer drive means being screwed into the block for rotation to move the blocks along the probe body. Includes a transducer arm (17) pivotally mounted between the screw means and the transducer and each block so that the movement of the blocks away from each other causes the radial pulling of the transducer towards the probe body. An apparatus as claimed in claim 1 or 2, wherein the apparatus is raised and causes movement of the blocks towards each other to cause radial outward movement of the transducer from the probe body.