JPS5815193A - Supporting device of reactor shroud - 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 reactor shroud support device that supports a shroud forming an outer wall of a nuclear reactor core in a stationary nuclear reactor pressure vessel.

A conventional reactor shroud (hereinafter simply referred to as shroud) support device is fixed around the bottom of the shroud whose upper end forms the outer wall of the reactor core, and whose lower end forms the reactor pressure vessel (hereinafter simply referred to as pressure vessel). It consists of nine shell support legs arranged in a columnar or cylindrical shape fixed to the inner court.

In the conventional shroud support device, all the weight of the core structure is supported by the shroud support legs, and there is no support part in the upper part of the shroud. Therefore, in the event of an earthquake, the upper part of the shroud is supported by the shroud support legs. There was a risk that large bending stress would occur.

The present invention has been made to eliminate or alleviate the drawbacks of conventional shroud support devices.

By restraining the horizontal relative displacement between the pressure vessel and the shroud against any horizontal load during an earthquake, the lateral vibration of the shroud is suppressed, and stress generation due to the lateral vibration is reduced. In addition, it is an object of the present invention to provide a shroud support device capable of absorbing relative displacement in the radial direction and vertical direction caused by the temperature difference between the shroud and the pressure vessel during nuclear reactor operation. will be explained with reference to the attached drawings.

l@1 In the figure, the upright ring-shaped shellaud support leg 1
Its upper end is welded and fixed around the bottom part 5 of the shroud 3 forming the outer peripheral wall of the reactor core 2, and its lower end is welded and fixed to the inner bottom surface of the fixed pressure vessel 4. Mayu, reinforcement rib 6
Its inner end is welded and fixed to the bottom 5 of the shroud 3, and its outer end is welded and fixed to the inner wall of the pressure vessel 4.

The plurality of sets of support structures 7 are arranged so that their respective horizontal center axes are placed on the radial line of the shroud 3 and the pressure vessel 4, and are located near the upper end of the shroud 3 and between the outer periphery of the shroud 3 and the inner periphery of the pressure vessel 4. radially in opposing positions and spaced apart from each other;
They are arranged horizontally at equal pitches around the circumference.

The second factor, in FIG. 3, the support structure 7 includes a first bracket 8 whose inner end surface is fixed perpendicularly and horizontally to the outer periphery of the shroud 3, and whose outer end surface is isolated from the inner periphery of the pressure vessel 4.
The upper surface of the pressure vessel 4 is placed perpendicularly and horizontally to the position facing the first bracket 8 on the inner circumference of the pressure vessel 4, and its upper surface approaches the lower surface of the first bracket 8, and the inner end surface is isolated from the outer circumferential surface of the shroud 3. A second bracket 9 whose outer end surface is fixed to the inner periphery of the bracket 4 is provided as a set.

A long groove 10 is dug into the upper surface of the second bracket 9 along its horizontal central axis, and the inner end is open and the opposite side is semicircular.

A cylindrical portion 11a having a diameter smaller than the width of the long groove 1O of the eccentric pin shaft 11 is fitted into the long groove 1O. The upper part of the eccentric pin shaft 11 has a smaller diameter than the cylindrical part 11m, and has a cylindrical part 11m and an eccentric shaft part 11b.
The portion 11b vertically passes through the first bracket 8 and is statically engaged therewith. A hexagonal hole (not shown) is provided at the center of the upper end surface of the shaft portion 11b.

B: The method for finding the L2 cloud 3 in the pressure vessel 4 is as follows.

After turning the eccentric pin shaft 11 with a tool (not shown) until the cylindrical portion 11a of the eccentric pin shaft 11 does not touch the long groove 1G (2) 11 surface of the second bracket 9, the shroud 3 is attached to the shroud support leg 1. Place it on top and weld it in place. Next, the shaft portion 11b of the eccentric pin shaft 11 is rotated using the tool.

In this case, the first cylindrical part 11 aFi rotates within the long groove 10 of the second bracket 9, but since the shaft part 11b and the cylindrical part 11m are eccentric, the outer periphery of the cylindrical part 11a contacts one side of the long groove 10. Stop (Figure 3). At this position, the shaft part 1
The outer circumference of the upper end of 1b is welded to the upper surface of the first bracket 8, and the eccentric pin shaft 11 is fixed to the first bracket 8.

(5) The number of supporting structures 7 is 4 or 8, and each of these is arranged at equal pitches in the circumferential direction along the inner periphery of the outer pressure vessel 4 of the shracto 3. In addition, the eccentric bottle shaft 110 cylindrical portion 1'1a and the second bracket 9 long groove 1
The position of contact with one side of 0 needs to be determined in consideration of the directionality of external forces such as earthquakes. Figure 4 shows a case in which 7 members or 7D representing each of the four sets of support structures 7 are arranged facing each other on orthogonal horizontal diameter lines, but in this case the columnar part 11m and The contact position line of the long groove 10 is shown in the drawing. That is, in the case of seven supporting structures, the contact position is on the right side of the long groove 10 toward the central axis of the pressure vessel 4, and is on the left side in 7B, on the right side in 7C, and on the left side in 7D.

The operation of the shroud support device according to the present invention will now be described.

The heavy reactor core 2 including internal structures is supported by a shroud support structure 4 via a seven-wheeled roof 3 . Near its upper end, the shroud 3 has a plurality of support structures 7Kc arranged in a radial (6) shape and arranged 2t'''.
The cylindrical part 11 of the shaft 11 is supported by the pressure vessel 4 and fixed to the first bracket 8 of the support structure 7.
Since point a is in contact with one side of the long groove 10 of the second bracket 9, even if a horizontal external force is applied in any direction due to an earthquake, the pressure vessel 4 and shroud 3 will not be displaced horizontally by this load. When restrained, 7 is formed, so even if the upper part of the chef's window 3 tries to sway laterally with respect to the lower part, the upright state is maintained by the restraining action of the support structure 7. This restraining action will now be explained with reference to FIG. 4. For example, the support structures 7C and 7D cooperate to restrain relative displacement due to an earthquake force in the X direction. Similarly, in the X1 direction, 7B is on the tail, ``!9Y
7B and 7C in the direction, and 7A%7D in the Y' direction
are each constrained.

Even if the temperature of the shroud 8 increases due to the action of the nuclear fuel in the core 2 and thermally expands in the radial direction, the cylindrical portion 11a of the eccentric pin shaft 11 freely slides in the longitudinal direction within the long groove 10. Therefore, the shroud 3 can absorb thermal expansion, and the shroud 3 is not constrained in any way by the vertical thermal expansion since the first bracket 8 can be completely freely displaced upwardly.

The shroud support device according to the present invention has its upper end fixed to the outer bottom of the shroud forming the outer wall of the reactor core, as described in detail above.

A shroud support leg whose lower end is fixed to the inner bottom of the pressure vessel housing the reactor core, and a shroud support leg disposed near the upper end of the shroud radially and horizontally between the outer periphery of the shroud and the inner periphery of the pressure vessel,
The support structure includes a first bracket, a second bracket, and a plurality of sets of eccentric pin shafts that support the shroud so as to be slidable in the radial and axial directions with respect to the pressure vessel while restraining displacement in the circumferential direction. By restraining horizontal relative displacement between the pressure vessel and the shroud due to this load against horizontal external forces in any direction during an earthquake, lateral vibration of the shroud is prevented, and support based on this vibration is prevented. It has the effect of preventing the generation of stress in the structural parts and also being able to cope with the heat expansion of 7 Euros due to the heat generated by the nuclear fuel in the reactor core.Also, due to the structure of the support structure.

Since it is possible to absorb installation errors between the shroud and the pressure vessel, it also has the effect of omitting the alignment process when installing the shroud.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a reactor pressure vessel equipped with a reactor shroud support device according to the present invention. FIG. 2 is an enlarged longitudinal sectional view of the support structure 7 of FIG. 1. 3 is a cross-sectional view taken along the line II in FIG. 2, and FIG. 4 is a diagram showing the relationship between the eccentric pin shaft 11 and the elongated hole 10 in FIGS. 2 and 3. DESCRIPTION OF SYMBOLS 1...Support leg, 2...Reactor core %3...Reactor shroud, 4...Reactor pressure vessel, 7...Support structure. 8...First putzket, 9...Second bracket, 1
0...Long groove, 11...Eccentric pin shaft (7317) Agent: Patent attorney Kensuke Norichika (and 1 others)
name) (9)

Claims (1)

[Scope of Claims] Nine support legs having an upper end fixed to the outer bottom of the shroud forming the outer wall of the reactor core and a lower end fixed to the inner bottom of the reactor pressure vessel; and a plurality of sets of support structures disposed horizontally and radially at wide intervals from each other at opposing positions between the inner peripheries of the pressure vessel. a first bracket, wherein the support structure has an inner end surface fixed perpendicularly and horizontally to the outer periphery of the sheroud, and an outer end surface separated from the inner periphery of the pressure vessel; The upper surface is perpendicular and horizontal to the inner periphery of the pressure vessel, the upper surface approaches the lower surface of the first shroud, the inner end surface is isolated from the outer periphery of the shroud, the outer end surface is fixed to the inner periphery of the pressure vessel, and 3-2 A second bracket having a long groove on the radius line of the rod, and a second bracket having a diameter smaller than the width of the long groove at the lower end, the outer periphery touches one of the side walls of the long groove, and T and B are inserted into the long groove. A support device for a nuclear reactor shroud comprising an eccentric cylinder shaft having an eccentric cylindrical portion and an eccentric bottle shaft fixed to the first bracket at an upper shaft portion.