JPS5814093A - Remote exchange device for retainer bolt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a jet pump that is a device for supplying a necessary flow rate of coolant to a reactor core in a boiling water nuclear reactor.

A jet pump according to the prior art will be explained below with reference to the drawings. FIG. 1 is a diagram showing the configuration of the reactor recirculation system, in which 1 indicates the reactor pressure vessel, a jet pump,
2 is installed in the reactor pressure vessel 1 and is provided together with a recirculation pump 3 as a reactor recirculation system, supplying the necessary flow rate to the reactor core 4 as the reactor output increases or decreases. ,
A part of the coolant 5 circulating in the reactor core 4 is taken out to the outside of the reactor pressure vessel l, and after being pressurized by the recirculation pump 3, it is used as a driving fluid for the jet pump 2 from the nozzle of the jet pump 2. sprayed at high speed. The remaining coolant is sucked into the jet pump due to the low pressure created in the absorption part at the nozzle outlet by this high-speed jet, and after being thoroughly mixed with driving water in the jet pump, it is sent to the lower core plenum 7. .

Figure 2 shows the structure of the jet pump. In the figure,
10 is riser elbow, 11 is riser pipe, 12u) lunge piece, 13 is elbow, 14 is nozzle, 15 is mixer, 16 is diffuser, 17 is bracket, 18
is a support, 19 is a wedge, 20 is a beam, 21 is a beam bolt, and 22 is a riser place. The riser elbow 10, the riser pipe 11, and the transition piece 12 are welded together, and the end of the riser elbow 10 is fixed to the reactor pressure vessel by welding. Further, in order to prevent the riser pipe 11 from vibrating in the lateral direction, it is fixed to the pressure vessel by a riser place 22. In a jet pump, the structurally and functionally important parts are elbow 13 and nozzle 1.
4. Mixer 15, especially the inner surface of the nozzle through which high-temperature, high-pressure water flows at high speed, wears out over time due to erosion, corrosion, etc. during operation, and if the inner diameter becomes too narrow, performance decreases, making it difficult to obtain the required core flow rate. Since there is a risk that the product may become damaged, consideration has been given to making it possible to remove and replace it. These elbow 13, nozzle 14, and mixer 15 are each assembled integrally by welding, but the connection parts with transition piece 12 and diffuser 16 are connected by a mechanical method rather than welding so that they can be removed. . Details of these are shown in FIGS. 3, 4, and 5.

FIG. 3 shows an external view of the attachment portion of the transition piece 12 and the elbow 13. In the figure, 11 is a riser pipe, 12
is a transition piece, 13 is an elbow, 14 is a nozzle, 15 is a mixer, 20 is a beam, 21 is a beam pole
-127 indicates a transition piece arm. FIG. 4 shows a detailed installation diagram of the transition bead 12 and elbow 13, which is the same as in FIG. In the figure, 12 is a transition piece, 13 is an elbow, 20 is a beam, 21 is a beam bolt, 23 is a retainer, 24 is a bolt, 25 is a tensile direction of the beam 20, 26 is a tightening direction of the beam bolt 21, and 27 is a transition piece. It is a peace arm.

The beam 20 and beam bolt 21 are inserted into a groove provided in the transition piece arm 27. Elbow 1
3 to the transition piece 12, the beam 20 is pulled in the tensile direction 25 using a handling tool (tensioner) prepared in advance, and while the tensile force is applied to the beam 20, the beam bolt 21 is tightened in the tightening direction. It is tightened in the direction of 26. In addition, the beam bolt 21 is attached to the elbow 1
3 with bolts 13 and retainer 23.

FIG. 5 shows the installation details of the mixer 15 and diffuser 16. 15 is a mixer, and 16 is a diffuser. The mixer 15 is mechanically inserted into the diffuser 16. And removable elbow 13
, the nozzle 14, and the mixer 15 shown in FIG. 2 to prevent lateral vibrations. A placket 1-17, a support 18, and a wedge 19 are provided. Bracket 1
7 surrounds the mixer 15 in a ring shape and is fixed to the riser pipe 11 by welding, and a wedge 19 is driven into the gap between the bracket 17 and the mixer 15 to prevent lateral vibration. The wedge 19 is attached to a support 18 welded to the mixer 15 to prevent it from falling off.

As explained above, the beam 20 and beam bolt 21 that tighten the removable elbow 13, nozzle 14, and mixer 15 are responsible for the pressure difference between the inside of the jet pump and the reactor, and the movement of the driving water inside the jet pump. Because it is necessary to ensure sufficient tightening force against the energy, the stress on the trowel is high due to its structure, and since it has a threaded part, the stress is especially high at the bottom of each thread, resulting in fatigue failure. It has the disadvantage of being prone to crevice corrosion.

Due to the above drawbacks, it is possible to replace only the jet pump beam 20 and beam bolt 21(5)-, but it is impossible to remove the beam bolt and retainer as they are. 2
It is necessary to loosen the bolt 24 fixing the retainer 23 to the elbow 13 and replace it. The jet pump and surrounding reactor equipment are the most important equipment located at the heart of the reactor, and in order to eliminate the above-mentioned drawbacks, the conventional elbow 13, nozzle 14, mixer 1
Removing the integral structure of No. 5 and replacing the beam 20 poses problems such as an increase in the amount of work and the work potential under high radiation conditions, so it is not possible to improve by replacing only the beam 20 and beam bolt 21. , is of utmost importance from the standpoint of plant reliability and safety.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and to replace only the beam and beam bolt after catching fibula fracture, crevice corrosion, etc. of the jet pump beam, which is subject to the highest stress, in advance. To provide a replacement handling device for replacing a bolt fixing a retainer to an elbow.

[6] A feature of the present invention is that in order to remove only the beam and beam bolt by remote control in reactor water, the bolt that fixes the retainer for beam bolt removal to the elbow is made of a base socket, joint par, hole, and hook. It is characterized by being able to be replaced by remote control using a replacement tool.

The present invention will be explained below based on the drawings. FIG. 6 shows a jet pump beam assembly retainer bolt 24 replacement device according to the present invention. The configuration of the device is base 29
, a hook 30, a ball 31, a joint top 32, and a socket 33. The method of using this device is to rotate the ball 2i supported by the base 29 via the beam bolt 21 with the hook 30, change the direction with the joint parr 32, and loosen the bolt 24 with the hook 33. 34 shows the direction of rotation of the ball, and 35 shows the direction of rotation of the joint par.

If the bolt 24 is loosened, the retainer 23 will move to the elbow 13.
This makes it possible to remove the beam 20 and the beam bolt 21 easily.

As a result, the beam 2o and beam holder in the prior art) 21k, the elbow 13 for replacing, the nozzle 14,
Compared to the method of removing the integral structure of the mixer 15, in the present invention only the beam 2o and the beam bolt 21 can be removed by means of the bolt 24 removal device.

Since the present invention uses a replacement device configured as described above, it is possible to remove only the beam and beam bolt, and compared to conventional methods, it has the effect of reducing work man-hours and radiation exposure. have

Although the most preferred specific embodiment has been shown in the above embodiment, similar effects can be obtained by changing the shape of each component or by using an integral structure due to the characteristics of the present invention.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of the reactor recirculation system, Figure 2 is an overall configuration diagram of the jet pump in Figure 1, and Figures 3 and 4 are installation details of the transition piece and elbow in Figure 1, respectively. 5 is a detailed view of the attachment of the adapter and diffuser shown in FIG. 1, and FIG. 6 is a front view of an embodiment of the retainer bolt remote replacement device of the present invention. 13... Elbow, 20... Beam, 21... Beam bolt, 23... Retainer, 24 River bolt, 28...
...Keeper 129...Base, 30...Hook,
31... Ball, 32... Joint top par, 33.
...Socket, 34...Pole rotation direction, 35 River joint, first time, 1st figure, 30, 4th section, 9th figure

Claims (1)

[Claims] 1. A retainer bolt remote replacement device consisting of a base, a hook 1, a pole, a joint topper, and a socket for replacing beams and beam bolts in jet pumps, which are internal reactor components in boiling water nuclear power plants.