CN107976486A - Nuclear power station control rod guide tubes and bundles split pin probe assembly - Google Patents

Abstract

The invention discloses a cotter pin probe assembly of a control rod guide cylinder of a nuclear power plant, which comprises a probe chip, a chip fixing frame for fixing the probe chip, a bottom plate and a first buffer assembly connected between the bottom plate and the chip fixing frame, the first There is also a second buffer assembly between the buffer assembly and the wafer holder. The second buffer assembly includes a middle plate connected to the first buffer assembly, a cylinder sleeved on the middle plate, and an elastic rubber fixed inside the cylinder. The wafer fixing frame is fixedly inserted in the elastic rubber ring and there is a gap between it and the middle plate. The height of the probe chip and the wafer fixing frame above the second buffer component is greater than the distance from the deepest part of the cotter pin groove to the lower end surface of the upper grid plate distance, which is the compression distance. The invention can adapt to positioning error and installation error, and the contact pressure between the ultrasonic probe and the cotter pin is constant, which is beneficial to the repeatability of ultrasonic inspection.

Description

Nuclear power plant control rod guide cylinder cotter pin probe assembly

technical field

The invention relates to the field of nuclear power detection, in particular to a cotter pin probe assembly of a control rod guide cylinder of a nuclear power plant.

Background technique

The cotter pin of the control rod guide cylinder is located in the upper reactor internals of the nuclear power plant reactor, and its function is to provide positioning and lateral support for the control rod guide cylinder, and is an important factor affecting whether the control rod can fall as required during power adjustment and emergency shutdown of the nuclear power unit . Cotter pin failures have occurred many times in foreign nuclear power plants. The consequences are reflected in two aspects. One is the dislocation of the control rod guide tube, which affects the falling time of the control rods. The other is that the broken cotter pin parts enter the primary circuit of the nuclear power plant as foreign objects and circulate , will damage other important equipment and affect the integrity of nuclear power equipment. Therefore, it is necessary to carry out in-service inspection on the cotter pin of the control rod guide cylinder to monitor its quality status during operation and improve the reliability, safety and integrity of the nuclear power plant.

In-service inspections are generally carried out during the overhaul of nuclear power units. During overhaul, the upper reactor internal component assembly is stored in the component pool as a whole. In order to conduct ultrasonic inspection of the key area of the cotter pin, a flat probe needs to be inserted into the groove of the cotter pin. The width of the groove in the installed state is between 2.696mm and 2.896mm, and limited by the size of the probe chip, the width of the probe assembly is 2.4mm. mm or so, the requirement for underwater positioning accuracy is higher. Moreover, the end of the cotter pin is recessed into the bottom surface of the upper grid plate by 37.75mm, which brings great difficulty to the observation and positioning of the end surface of the cotter pin. In addition, after the nuclear power unit has been in operation for more than 20 years, factors such as deformation of parts and assembly tolerances may cause the cotter pin to be deflected to a certain extent, so the probe assembly must be flexible to adapt to this situation; in addition, due to the ultrasonic probe and the cotter pin Constant contact pressure is conducive to the repeatability of ultrasonic inspection, and in order to provide such a constant pressure, it is often necessary to set up a pressure detection and adjustment mechanism, which is extremely difficult to set up on a small probe assembly.

Contents of the invention

The purpose of the present invention is to provide a nuclear power plant control rod guide cylinder cotter pin probe assembly capable of self-adaptation and providing constant contact pressure so as to ensure repeatability of detection.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical scheme: a nuclear power plant control rod guide cylinder cotter pin probe assembly, which includes a probe wafer, a wafer holder for fixing the probe wafer, a base plate, and a base plate connected to the base plate and The first buffer assembly between the wafer holders, a second buffer assembly is also provided between the first buffer assembly and the wafer holder, and the second buffer assembly includes The connected middle plate, the cylinder sleeved on the middle plate, and the elastic rubber ring fixed inside the cylinder, the wafer holder is fixedly inserted in the elastic rubber ring and connected to the middle plate There is a gap between them, and the height of the probe wafer and the wafer holder above the second buffer assembly is greater than the distance from the deepest part of the cotter pin groove to the lower end surface of the upper grid plate, which is the compression distance.

Optimally, the probe assembly further includes a cover plate that is covered on the barrel and sleeved on the wafer holder.

Optimally, the lower end surface of the middle plate has an extension column extending downward and an annular plate extending outward along the radial direction of the extension column from the lower end of the extension column, and the first buffer assembly includes a plurality of The guide posts in the annular plate and the bottom plate, the support springs sleeved on each of the guide posts and between the annular plate and the bottom plate, the two ends of the guide posts are provided to prevent them from moving from the annular plate. and nuts that came off the bottom plate.

Optimally, the lower end of the wafer holder has a card plate extending radially outward, a through hole is opened in the middle of the elastic rubber ring, and the inner wall of the through hole is provided with a card that matches the fixing ring. slot, and the card board is set in the slot.

Optimally, the compression distance is 1-5mm.

Further, the clamping board is in the shape of a racetrack, which has two parallel straight sides and an arc-shaped side connected between the two straight sides.

The beneficial effect of the present invention is that: the present invention can adapt to the positioning error and the installation error of the internal components of the stack, and the contact pressure between the probe chip and the cotter pin is constant, which is beneficial to the repeatability of the ultrasonic inspection.

Description of drawings

Figure 1: Perspective view of the probe assembly;

Figure 2: Sectional view of the probe assembly;

Figure 3: Sectional view of the probe assembly;

Figure 4: After the probe assembly is tightly attached to the cotter pin groove, the distance between the probe assembly cover plate and the bottom surface of the upper grid plate is 3mm.

Detailed ways

Below in conjunction with the embodiment shown in the accompanying drawings, the present invention is described in detail as follows:

As shown in Figures 1, 2 and 3, the nuclear power plant control rod guide cylinder cotter pin probe assembly includes a probe wafer 71, a wafer holder 72 for fixing the probe wafer 71, a base plate 78, connected to the base plate 78 and the The first buffer assembly between the wafer holders 72 and the second buffer assembly disposed between the first buffer assembly and the wafer holder 72 .

The second buffer assembly includes a middle plate 75 connected to the first buffer assembly, a cylinder 74 sleeved on the middle plate 75, an elastic rubber ring 79 fixed inside the cylinder 74 and a seal. The cover plate 73 that is covered on the cylinder body 74 and sleeved on the wafer holder 72, the wafer holder 72 is fixedly inserted in the elastic rubber ring 79 and exists between the middle plate 75 Gap, the height of the probe wafer 71 and the wafer holder 72 above the second buffer assembly is greater than the distance from the deepest part of the cotter pin 721 groove to the lower end surface of the upper grid plate 722, which is the compression distance, so The compression distance is 1-5mm. The lower end of the wafer holder 72 has a clamping plate 716 extending radially outwards, the middle part of the elastic rubber ring 79 is provided with a through hole, and the inner wall of the through hole is provided with a matching plate 716. The card slot, the card plate 716 is locked in the card slot. The clamping board is in the shape of a racetrack and has two parallel straight sides and an arc-shaped side connected between the two straight sides. When the probe wafer 71 needs to be rotated adaptively, the elastic rubber ring 79 rotates and deforms with the wafer holder 72, and resets after the detection is completed.

The lower end surface of the middle plate 75 has an extension column 714 extending downward and an annular plate 715 extending outward from the lower end of the extension column 714 along the radial direction of the extension column 714. The first buffer assembly includes a plurality of The guide posts 76 in the annular plate 715 and the bottom plate 78, the support springs 77 sleeved on each of the guide posts 76 and between the annular plate 715 and the bottom plate 78, the guide posts 76 two ends are provided with the nut 717 that prevents it from coming off from annular plate 715 and base plate 78.

As shown in Figure 4, when the top of the probe assembly touches the end face of the cotter pin 721, if there is a certain positioning deviation or installation error, the probe assembly can automatically adjust its attitude by deformation of the elastic rubber ring 79 and the support spring 77; After arriving at the top of the groove of the cotter pin 721, the vertical lifting mechanism that drives the probe to move up and down (the mechanism such as the cylinder can be realized, which is not the focus of the present invention, and will not be described in detail here) continues to rise until the cover plate 73 contacts the upper grid plate 722 , the support spring 77 and the elastic rubber ring 79 start to compress. At this time, the contact pressure between the probe assembly and the cotter pin 721 is the elastic force that the support spring 77 and the elastic rubber ring 79 produce a total deformation of 1-5mm, and remains unchanged. In this embodiment, the elastic coefficient of the rubber is 10N/mm, By adjusting the glue content and hardness, the best pressure on the probe is 30N, so the best deformation is 3mm. The probe assembly has certain flexibility, adaptive positioning error and installation error, and can realize the constant contact pressure between the ultrasonic probe and the cotter pin 721 within the required range without additional pressure detection equipment, which is beneficial to the repeatability of ultrasonic inspection.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (6)

1. a kind of nuclear power station control rod guide tubes and bundles split pin probe assembly, it includes probe chip, for fixing the probe crystalline substance Chip fixed frame, bottom plate and the first Buffer Unit being connected between the bottom plate and the chip fixed frame of piece, it is special Sign is：The second Buffer Unit, the second buffering group are additionally provided between first Buffer Unit and the chip fixed frame Part is including the middle plate being connected with first Buffer Unit, the cylinder being sheathed on the middle plate and is fixed on the cylinder Internal elastic rubber ring, between the chip fixed frame fixation is inserted in the elastic rubber ring and exists between the middle plate Gap, the height that the probe chip is higher by the second Buffer Unit part with the chip fixed frame are more than split pin groove most The distance of the supreme Turbogrid plates lower face in depths, the distance are compression distance.

2. nuclear power station control rod guide tubes and bundles split pin probe assembly according to claim 1, it is characterised in that：The probe Component further includes the cover board for being covered on the cylinder and being sheathed on the chip fixed frame.

3. nuclear power station control rod guide tubes and bundles split pin probe assembly according to claim 1, it is characterised in that：The middle plate Lower face is with the extending column extended downwardly and by the annular slab that extends radially outwardly of the extending column bottom along extending column, institute State the first Buffer Unit include lead that is multiple while being arranged in the annular slab and the bottom plate, be sheathed on it is each described Support spring on lead and between the annular slab and the bottom plate, the lead both ends, which are equipped with, prevents it from ring The nut to come off on shape plate and bottom plate.

4. nuclear power station control rod guide tubes and bundles split pin probe assembly according to claim 1, it is characterised in that：The chip Fixed frame bottom has the snap-gauge extended radially outward, and the through hole of perforation is offered in the middle part of the elastic rubber ring, described Through-hole wall is equipped with the card slot to match with the snap-gauge, and the snap-gauge is arranged in the card slot.

5. nuclear power station control rod guide tubes and bundles split pin probe assembly according to claim 1, it is characterised in that：The compression 1~5mm of distance.

6. nuclear power station control rod guide tubes and bundles split pin probe assembly according to claim 4, it is characterised in that：The snap-gauge In runway shape, it has two parallel straight flanges and the arc-shaped side being connected between two straight flanges.