JPS62147395A - Clamping device for in-pile structure - 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] [Technical Field of the Invention] The present invention relates to a fastening device for reactor internals that fastens reactor internals, and particularly for fastening a shroud head to a core part of a nuclear reactor such as a shroud. This invention relates to a fastening device for reactor internals.

[Technical background of the invention and its problems]

In a boiling water nuclear reactor, a reactor core 1 is formed by loading a large number of fuel assemblies into a reactor pressure vessel. As shown in FIG. 4, the loaded fuel assembly has its lower part attached to the core support plate 2.
The upper parts are supported by upper lattice plates 3, and the outer periphery of the core 1 is surrounded by a shroud 4. The top of the shroud 4 is covered with a shroud head 5, forming a brenum above the core. A large number of standpipes are arranged in the shroud head 5. A steam-water separator 7 is provided at the top of each stand pipe, and the steam-water separator 7 performs gas-liquid separation to generate steam.

During operation of a nuclear reactor, the pressure and temperature of the reactor core increase due to the fission reaction of the nuclear fuel. In order to support the internal pressure acting on the shroud head 5 during operation of the nuclear reactor and the overturning load during an earthquake, the shroud head 5 is fastened to the shroud 4 with several dozen shroud head bolts 8.

As shown in FIGS. 5 and 6, the shroud head bolt 8 accommodates an inner rod 10 that extends through a cylindrical outer pipe 9.
are inner rod upper 10a and inner rod lower 1
0b are integrally joined by welding. The inner rod lower 10b protrudes downward from the lower end of the outer pipe 9, and a tea bar 11 is provided at its tip.

The tee bar 11 engages with a shroud head bolt lug (bracket) 12, and this shroud head bolt lug 1
It is supported at the lower end of 2.

On the other hand, the upper part of the inner rod upper 1oa is screwed to a nut 13 such as a hexagonal nut.
3, it is fixed to the outer pipe 9 via the nut lock 14 and head 15.

The nut lock 14 is biased by a spring 16 and fits into the corner of the nut 13, and during normal operation, the nut 13
The rotation of is restricted.

A cylindrical base 18 is fixed to the lower end of the outer pipe 9, and this base 18 is provided in a lug groove of a shroud head bolt lug 19 of the shroud head 5.

Further, a large number of standpipes arranged on the shroud head 5 and steam/water separators 7 provided at the ends of the standpipes 6 are supported by upper and lower guide rings 20 and 21, respectively. Upper and lower guide rings 20.
21 supports the shroud head bolt 8 in the horizontal direction, while a head 22 and a spacer 23 are provided at the support portion of the shroud head bolt 1-8, and these heads 2
2 and spacer 23 are the upper and lower guide rings 2
It is engaged with a 0.21 engagement hole.

Incidentally, the shroud head 5 is fastened to the shroud 4 using shroud head bolts 8. During this tightening, the shroud head bolt 8 is inserted from above through the upper and lower guide rings 20, 21 with the tee bar 11 facing downward. After this insertion, the inner rod 10 is rotated 90 degrees using a special wrench (not shown), and the tee bar 11 is locked in the lug groove of the shroud head bolt lug 12.

In this case, the inner rod 10 constituting the shroud head bolt 8 is made of Inconel 600 material, and the outer pipe 9, shroud 4, and shroud head 5 are made of stainless steel.

Since Inconel 600 has a lower heat + tl rate than stainless steel, the shroud 4 and shroud head 5 are firmly tightened when the temperature increases due to reactor operation.

Further, the shroud head 5 is removed from the shroud 4 during periodic inspection of the nuclear reactor or during fuel replacement. When removing the shroud head 5 from the shroud 4, push down the nut lock 14 and tighten the nut 13 with a special wrench.
and push down the inner rod 10 and tee bar 11, rotate the inner rod 10 90 degrees, and push down the tee bar 11 and shroud head bolt lug 12.
disengage with. By pulling up the shroud head bolt 8 together with the shroud head 5 in this state, the shroud head bolt 8 is removed. Therefore, the shroud head bolt 8 is attached to the shroud head 5.
Once installed on the shroud head bolts 1 to 5a, there is no need to remove it from the shroud head 5.

However, if the shroud head bolts 8 are damaged during the installation and removal work of the shroud head 5, the upper and lower guide rings 20. It can be removed by pulling it upward through 21.

By the way, there is a recent trend toward increasing the capacity of nuclear power plants, and when increasing the capacity of a nuclear power plant, the diameter of the shroud 4 and shroud head 5 must be increased, and the number of shrouds in the steam/water separator 7 must be increased. An increase will be required. At this time, it may be necessary to arrange the outermost steam/water separator 7 outside the outer periphery of the shroud head 5. Also,
As the capacity of nuclear power plants increases, earthquake loads, etc.
rJ heavy conditions are more severe than before. Therefore, in the shroud head bolt 8, it is necessary to increase the diameter of the outer pipe 9 and the inner rod 10, or increase the number of them.

However, the outermost energy and water power! ! If the vessel 7 is placed outside the outer circumference of the shroud head 5, there will be a problem of interference between the steam separator 7 and the shroud head bolts 8, so it may be necessary to increase the number of shroud head bolts 8 or There are significant restrictions on increasing the diameter of the inner rod 10. Therefore, it has been difficult to provide the shroud head bolt 8 with sufficient strength.

Roughly speaking, the upper guide link 21 is the outermost steam and moisture collector 7
When replacing the shroud head bolt 8, the widest tee bar 11 is attached to the upper guide ring 2.
It is necessary to pass through the engagement hole formed in 1. However, it is very difficult to smoothly insert the tee bar 11 of the shroud head bolt 8 through the engagement hole, making it difficult and time consuming to replace the shroud head bolt 8. Furthermore, when designing the shroud head bolt 8, interference with the steam/water separator 7 must be fully considered, and the design of the shroud head bolt 8 is subject to extremely severe design constraints, making it difficult.

[Object of the Invention] The present invention has been made in consideration of the above-mentioned circumstances, and it maintains sufficient strength even when the shroud head bolt is made smaller and lighter CD, and also allows for the connection between the shroud head bolt and the steam separator when attaching and detaching the shroud head bolt. It is an object of the present invention to provide a fastening device for reactor internals that can effectively prevent interference and facilitate the replacement of shroud head bolts.

[Summary of the invention]

The fastening device for reactor internals according to the present invention includes a lower guide ring installed around a stand pipe provided on a shroud head that covers the top of the shroud, and a steam separator provided at the top of the stand pipe. an upper guide ring is installed around the upper guide ring, a plurality of engagement guide grooves extending in a radial direction are provided in the upper and lower guide rings to face each other, and the shroud head bolt is detachably attached to the engagement guide groove from the side. It is characterized by the fact that it has been provided.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fastening device for reactor internals according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the configuration of a shroud head bolt 30 as an example of a fastening device for internal structures of a nuclear reactor. ) 32.The shroud head bolt 30 has a short outer pipe 33 with a large diameter, and an inner rod 34 extends through the outer pipe 33.The inner rod 34 also has a large diameter and a short length. While it is formed into a short length,
The inner rod 34 protrudes downward from the outer pipe 33, and a tee bar 35 is integrally attached to the lower end of the shroud head bolt lug 31a of the shroud head 31 and the shroud head bolt lug (bracket) 32a of the shroud 32 by welding or the like. Fixed.

On the other hand, a tube 37 is placed on the top of the outer pipe 33. The tube 37 has a large-diameter tube lower 37a similar to the outer tube 33, and this dual blower 37.
It integrally includes a tube upper 37b having a smaller diameter than that of the upper tube 37b.

The tube lower 37a has a function as a neck, and a female thread is formed on its inner periphery, and the upper part 34a of the inner rod 34 is screwed to this female thread. A small diameter shaft 38 inserted into the tube upper 37b is integrally fixed to the top of the inner rod 34.

Shirt] ~ 38 extends upward and protrudes inside the tube upper 37b, and has top nuts 1 ~ 3 such as hexagonal nuts attached to the protruding portion.
9 is screwed together, while the top of the shaft 38 is provided with a diametrically extending rectangular indicator protrusion/IO. This protrusion 40 is formed to match the longitudinal direction of the tee bar 35.

The dupe 37 is also integrally joined to the top nut 39 and extends upwardly through lower and upper guide rings 41 and 42 that hold the standpipe and the steam separator (see Figure 4). A nut lock 43 is slidably provided. The nut lock 43 is biased upward by a spring 44 and engages with a corner of the top nut 39 to prevent the top nut 39 from rotating. Oak 1
- The downward slide of the lock 43 is guided by the guide pin 45.

As shown in FIG. 2, an engagement guide groove 47 extending in the radial direction is cut out from the outside of the upper guide link 42 that holds the steam/water separator. 37b is engaged so as to be freely inserted and withdrawn from the side. In the engagement guide groove, a bulging locking engagement groove 48 is formed at the groove bottom on the radially inward side, and a sleeve 49 engages with this locking engagement groove 48 so as to be slidable in the vertical direction. 49 rotation stops J:
It's becoming a sea urchin. The sleeve 49 is inserted into the tube 37 of the shroud head bolt 30, and when the shroud head bolt 30 is installed, the lower portions of the four sleeves are engaged and prevented from rotating. This allows shroud head bolt 3
0 horizontal support is provided and rotation of the four sleeves is restrained.

Also, a lower guide link 41 that holds the stand pipe
As shown in FIG. 3, an engagement guide groove 50 extending in the radial direction is also provided. 51, and a cylindrical spacer 52 is adapted to engage with this engagement groove 51.The spacer 52 is integrally joined to the tube upper 37b of the shroud head bolt 30.The spacer 52 is connected to the shroud head bolt 30. When the bolt 30 is installed, it engages with the bulging engagement groove 51, supports the shroud head bolt 30 in the horizontal direction, and prevents it from coming out in the lateral direction.

Furthermore, a cylindrical base 53 provided on the shroud head bolt lug 31a is integrally joined to the lower part of the outer pipe 33 of the shroud head bolt 30.

The base 53 is fitted into the lug groove of the shroud head bolt lug 31a so that it can slide up and down and is prevented from rotating. A window 54 is provided at the bottom of the base 53 to restrict the rotational position of the inner rod 34. A pin 55 protruding from the inner rod 34 is engaged with this window 54, and this engagement controls the rotational position (orientation) of the tee bar 35 in the tightened or loosened state.

Here, the inner rod 34 has a higher heat U3 III? compared to the shroud 32 and the shroud head 31. Made of material with a small ratio. Since the shroud 32 and the shroud head 31 are usually made of stainless steel, the inner rod 34 is made of a material having a smaller coefficient of thermal expansion than stainless steel, such as Inconel 600. In addition, the inner rod 34 and the outer pipe 33 are shorter than before, and the due blower 37a as a nut screwed to the inner rod 34 is attached to the lower guide ring 41.
It is set so that it is located below. In this case, 1. The tightening force due to the thermal WBfM difference of the shroud head bolt 30 can be adjusted by making part or all of the outer pipe 33 of a material that is the same as or similar to that of the inner rod 34.

Next, the operation of attaching and detaching the shroud head bolt 30 will be explained.

When tightening or loosening the shroud head bolts 30, push down the nut locks 43 against the spring force of the springs 44, and tighten the three top nuts and the nut locks 43.
Release the fitting with 3.

In this state, rotate the special wrench. A special wrench (not shown) includes a socket that engages the three top nuts and a shirt 1.
- The top projection 40 and the engaging socket are independently rotatable. By rotating a special wrench,
The three top nuts rotate and the tube 37 integral with the top nut 39 is rotated and tightened. By this rotation of the tube 37, the inner rod 34, which is threadedly connected to the due blower 37a, is moved forward and backward. The inner rod 34 is tightened by moving it upward, and loosened by moving it downward.

Then, the shroud head pole 1-30 is loosened by the downward movement of the inner rod 34. At this time, the socket of the special wrench that engages with the rectangular protrusion is used to
The rotational position (orientation) of the bottle 5 can be confirmed and adjusted using a special wrench.
By rotating the inner rod 34 such that the inner rod 34 engages with the right side of the base window 54, the tee bar 35 is released from being locked with the shroud head bolt lug 32a of the shroud 32.

Therefore, the tube 737 of the shroud head bolt 30
The tube upper 37b and the shaft 38 only transmit the rotational force of a special wrench to the tube lower 37a as a nut and the inner rod 34 during the initial tightening or loosening work of the shroud head bolt 30. Since the upper tube 37b and the shaft 38 are not adversely affected by the internal pressure load generated during nuclear reactor operation, the overturning load during an earthquake, or the tightening load caused by the difference in thermal expansion, the tube upper 37b and the shaft 38 can be made smaller and smaller in diameter. By making the diameter smaller, interference with the outermost steam separator can be eliminated.

By the way, when attaching the shroud head bolt 31a to the shroud head 31, first align the engagement protrusions formed on the base 53 and the sleeve 49, and then engage the flange 49a of the sleeve 49 with a special jig. , lift the entire shroud head bolt 30 and place it outside the upper and lower guide rings 41,42.

At this time, the tee bar 35 of the shroud head bolt 30
a direction in which the longitudinal direction of is perpendicular to the inner peripheral wall surface of the reactor pressure vessel,
That is, with the shroud aligned with the lug groove of the lug 32a, and with the shroud head bolt 30 slightly raised above its installation level, the tube 37 is inserted into the engagement shown in FIGS. 2 and 3. Insert it laterally into the guide groove 47°50 from the side. After inserting into the engagement guide groove 47.50, the tube 37 is inserted so as to reach the engagement groove 48.51 at the bottom of the groove, and after reaching this point, the shroud head bolt 30 is lowered slightly, and the base 5
3, spacer 51, and sleeve 49 are engaged with the lug grooves of the shroud head bolt lugs 31a and the engagement grooves 47.50 of the upper and lower guide rings 41.42.

After that, rotate the special wrench and start with Teeba 35.
90 degrees to engage the lower end of the shroud head bolt lug 32a of the shroud 32. The Diva 35 is rotated by rotating the bottle 55 protruding from the inner rod 34 until it comes into contact with the base window 54 shown in FIG. 1, and then rotating the top nut 39 with a special wrench. Lift up the inner rod 34. By lifting this inner rod 34, the shroud head bolt 30
Installation is completed.

If the shroud head bolt 30 is to be removed due to damage to the shroud head bolt 30, the shroud head bolt 30 may be operated in the opposite manner to the installation procedure. In this way, the shroud head bolt 30 can be attached and detached from the side of the air/water valve.

The shroud head bolt 30 that tightens the shroud head 31 to the shroud 32 has a tightening force that is determined by the inner rod 34 with the outer pipe 33 and the tee bar 35,
This is achieved by the cylindrical nut (tube lower) 37a, and there is no need to use the tube upper 37t) or shaft 38 as a strength member during reactor operation, and the tube upper 37b or shaft 38 can be made smaller in diameter and smaller. Therefore, the shroud head bolt 30 can be attached and detached without interfering with the outermost steam separator.

Moreover, the cylindrical nut (tube lower) 37a, outer pipe 33, and inner rod 34, which serve as strength members during reactor operation, are all disposed below the lower guide ring 41, so they can be made shorter and have a larger diameter. This allows the shroud head bolt 30 to have sufficient strength.

In one embodiment of the present invention, an example has been described in which the lower end tee bar of the shroud head bolt is engaged with the shroud head bolt lug of the shroud. You can also do this.

〔Effect of the invention〕

As described above, in the fastening device for reactor internals according to the present invention, upper and lower guide rings are installed around the steam separator and the stand pipe, respectively, and the upper and lower guide rings are provided with tli beams. A plurality of engagement guide grooves extending in the direction of the thickness are provided facing each other, and the shroud head bolt is provided in the engagement guide groove so that it can be attached and detached from the side, so that the shroud head bolt can be easily and easily attached to the reactor internal structure from the side. It can be installed and removed smoothly, and the strength member of the shroud head bolt can be shortened. Therefore, the shroud head bolt can be made smaller and lighter, and sufficient strength can be maintained even if the shroud head bolt is made smaller and lighter.

In addition, by making the strength member of the shroud head bolt shorter, it is possible to reduce the diameter of the shaft and tube other than the strength member, and when installing and removing the shroud head bolt, the air and water valve ll! Interference with the device can be effectively prevented. Therefore, the shroud head bolt can be replaced easily and smoothly.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the fastening device for reactor internals according to the present invention, without showing the structure around the shroud head bolt, and Fig. 2 shows the structure along line I[-II in Fig. 1. Planar sectional view,
Figure 3 is a sectional view taken along the line ■-■ in Figure 1, and Figure 4 is a cross-sectional view of the
FIG. 5 is a vertical cross-sectional view of the reactor internals of a water-extension reactor, and FIGS. 5 and 6 are views showing conventional fastening devices for the reactor internals, respectively. 30... Shroud head bolt, 31... Shroud head, 31a, 32a... Shroud head bolt lug, 32... Shroud, 33... Outer pipe, 34... Inner rod, 34a... Threaded portion, 35...Teeva, 37...Tube, 37a
...Due blower (nut), 37b...Tube upper, 38...Shaft, 39...Top nut,
40... Indication protrusion, 41... Upper guide ring, 4
2... Lower guide ring, 43... Nut lock,
47.50...Engagement guide groove, 48.51...Engagement groove, 49...Sleeve, 51...Spacer, 53...
...Base, 54...Base window, 55...Bin. Applicant's agent Hisashi Hatano I Figures 2 Figures 3 Figures 4 Figures, 5 Figures 6

Claims (1)

[Claims] 1. A lower guide ring is installed around a standpipe provided on a shroud head that covers the top of the shroud, and an upper guide ring is installed around a steam separator provided at the top of the standpipe. a plurality of engagement guide grooves extending in a radial direction are provided in the upper and lower guide rings to face each other, and a shroud head bolt is provided in the engagement guide groove so as to be detachable from the side. A fastening device for reactor internals. 2. The shroud head bolt has an outer pipe and an inner rod that extends through the outer pipe and has a tea bar at the lower end, and the upper part of the inner rod is attached to a tube lower as a nut placed on the outer pipe. 2. The fastening device for reactor internals according to claim 1, wherein the screw connection is screwed and the screw connection portion is located below the lower guide ring. 3. The furnace internal structure according to claim 2, wherein a shaft extending in the axial direction is integrally formed on the top of the inner rod, and an indicator protrusion that corresponds to the longitudinal direction of the tea bar is integrally provided on the top of the shaft. fastening device. 4. The tube placed on the outer pipe is integrally equipped with a large-diameter tube lower serving as a nut and a narrow-diameter tube upper extending upward from the tube lower, and a top nut is integrally provided at the top of the tube upper. The fastening device for a reactor internal structure according to claim 2, wherein the tube upper is provided with a sleeve and a spacer that can be engaged with the engagement guide grooves of the upper and lower guide rings. 5. The fastening device for a reactor internal structure according to claim 2, wherein the inner rod is formed of a material having a smaller coefficient of thermal expansion than the upper lattice plate of the shroud or the shroud head. 6. The fastening device for a reactor internal structure according to claim 2, wherein at least a portion of the outer pipe is formed of a material having a coefficient of thermal expansion that is the same as or similar to that of the inner rod.