JPS6020182A - Upper support for 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 [Technical Field of the Invention] The present invention relates to a shroud upper navot that is installed in a nuclear reactor pressure vessel and has a function to prevent the shroud from swinging to iJ3 during an earthquake.

[Technical Background of the Invention 1] A shroud installed in a nuclear reactor pressure vessel (which supports the internal core and is combined with a shroud head depicting a steam/water separator, and has the function of supporting this) .

Figure 1 shows a pressure vessel 1 and a shroud 2 installed inside it.
The lower end of the shroud 2 is fixed to the pressure vessel 1 by welding. Shroud side brackets 1 to 3 protruding left and right outward near the upper end of the shroud 2 are engaged with a guide rod 4 on the pressure vessel 1 side.

Figure 2 does not show the outline of a part of the leave board located near the upper end of the shroud. is fixed. The lower end of this guide rod 4 is a free end, and the above-mentioned shroud side bracket 3 is attached thereto.
7 is engaged with a bracket on the shroud head 6 side which is placed and fixed on the shroud 2.

The guide rod 4 functions as a guide when removing the shroud head 6, and as shown in FIG. As shown in FIG. 4, it is loosely engaged with the through hole 3a of the shroud side bracket 3.

The reason why the guide rod 4 is supported at one end and the engagement between the guide rod and the bracket 7.3 is loose so that a large play is formed between them is because the guide rod 4 is supported at one end of the shroud head 6. This is due to the fact that it only needs to function as a guide, and that it absorbs the relative displacement caused by the difference in thermal expansion between the pressure vessel 1 and the shroud.

Therefore, in the conventional shroud upper support, the guide rod 4 itself does not have the function of supporting the shroud.

Problems with F-back m technology] In other words, as mentioned above, the shroud supports the core inside and the shroud head at the top, and has a vertically elongated shape, but conventionally only the lower end was connected to the pressure vessel. Because it was fixed, it was vulnerable to lateral vibration during earthquakes, and severe stress was applied to the lower end of the shroud.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems in the background art, and it reduces the stress generated in the shroud due to lateral vibration during an earthquake, increases the allowable margin, and improves the margin for safety. The purpose is to provide an upper shroud support that allows for a certain design.

[Summary of the Invention] That is, the present invention provides a guide rod arranged vertically near the inner upper end of a pressure vessel, an upper bracket supporting the vicinity of the upper end of the guide rod on the pressure vessel, and a guide rod arranged vertically near the inner upper end of the pressure vessel. a sleeve that is fixed via the lower bracket and that fits into, supports and covers the outer periphery of the lower end of the guide rod; a shroud-side bracket that is fixed to the shroud and has a groove that is engaged with the outer periphery of the sleeve; This shroud upper support is characterized by comprising a shroud side bracket provided with a concave groove that projects outward from the mounted shroud head and is engaged with the guide rod.

[Embodiments of the Invention] The present invention will be described in detail below with reference to FIGS. 5 to 7. In these figures, the same members as in FIGS. 1 to 4 are given the same reference numerals.

In the embodiment shown in FIG. 5, shroud upper supports are attached at four locations in the circumferential direction of the shroud 2 at intervals of 90'.

FIG. 6 shows an enlarged view of one of the shroud upper supports, in which a guide rod 4 extending in the vertical direction is arranged inside near the upper end of the pressure vessel 1; It is inserted into the sleeve 8a of the lower bracket 8 that protrudes inwardly, and the vicinity of the upper end is welded to the upper bracket 9 that protrudes inwardly of the pressure vessel 1.

The shroud head side bracket 7 has a concave groove 78 that is guided with a large clearance relative to the guide rod 4 in the same manner as described with reference to FIGS. 2 and 3.

In addition, since the shroud side bracket (10) that protrudes outward from the shroud 2 functions as a part of the iJ In addition, as shown in Fig. 7, 11J (circumferential dimension of the pressure vessel 1) of the recess 1M10a is dimensioned so as to have a slight clearance with respect to the outer diameter of the sleeve 8a of the lower bracket. However, the radial dimension of the groove 10a is set to be relatively large so as to form a clearance so as to absorb the difference in thermal expansion between the pressure vessel 1 and the shroud 2.

In the shroud upper support of the present invention having a 4Fi structure as described above, the guide rod 4 is supported at two points near the upper and lower ends by the upper bracket 9 and the lower bracket 1 on the pressure vessel 1 side, and is supported at two points on the shroud side bracket 1. 10 is supported with a slight circumferential clearance relative to the sleeve 8a of the lower bracket 8, the upper end of the shroud is earthquake-proofed, and the lateral shaking during an earthquake is reduced to a large extent. In addition, the shroud side bracket 10 and the sleeve 8a of the lower bracket
A large radial clearance is provided between the bracket 10 and the sleeve 8a, and since the bracket 10 and the sleeve 8a can move independently in the vertical direction, the difference in thermal expansion between the pressure vessel 1 and the shroud 2 in the radial direction and the vertical direction can be absorbed. can do.

However, in the present invention, it is not necessarily necessary to provide all four sleeves on the bracket 10 side, and a considerable vibration damping effect can be obtained even if the sleeves are provided only on two facing each other.

In the above explanation, the vicinity of the upper end of the guide rod 4 is welded to the upper bracket 9, and the vicinity of the lower end is inserted and supported by the sleeve 8a of the lower bracket 8. However, these brackets can be installed upside down. It's okay. In this case, the recessed groove 1'' of the shroud side bracket is sized to have a small dimension with respect to the outer circumference of the guide rod engaged therein.

[Effects of the Invention] As described above, the shroud upper support of the present invention constitutes an earthquake-resistant support by utilizing the conventionally used shroud side bracket position, so the vibration resistance of the shroud is improved and the shroud is The stress at the bottom part is alleviated, and the space in the downcomer part can be saved, so that the impact on the equipment installed there in terms of flow characteristics and handling can be reduced.

Furthermore, since both the upper and lower guide rods are firmly supported by the brackets on the pressure vessel side, positioning when installing the shroud head becomes easier.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a pressure vessel showing a conventional shroud upper support, Figure 2 is a longitudinal cross-sectional view showing details of a conventional shroud upper support, and Figures 3 and 4 are
A cross-sectional view along the ■-■ line and the Iv-Iv line in FIG. 2,
FIG. 5 is a cross-sectional view of a pressure vessel equipped with the shroud upper support of the present invention, FIG. 6 is a longitudinal cross-sectional view of an embodiment of the shroud upper support of the present invention, and FIG. −
FIG. 3 is a cross-sectional view taken along line vI. 1......Pressure vessel 2...Shroud 3...
...Shroud side bracket 4...
・・・・・・Guide rod 5・・・・・・・・・Pressure vessel side bracket 6・
・・・・・・・・・Shroud head 7・・・・・・
...Shroud head side bracket 8...
......Lower bracket 8a...
・・Sleeve 9・・・・・・・・Upper bracket 10・・・・
・・・・・・・・・Patent attorney representing Shroud side Kensuke Chika (and 1 other person) Figure 3 Figure 4' m5 Figure 6 Figure 7

Claims (1)

[Claims] (1) A guide rod arranged vertically near the inner upper end of the pressure vessel, an upper bracket supporting the pressure vessel near the upper end of the guide rod, and a lower bracket attached to the pressure vessel. a shroud-side bracket that is fixed to the shroud and has a groove that engages with the outer periphery of the sleeve; A shroud upper support comprising: a shroud-side bracket having a concave groove that projects outward from the rad head and is engaged with the guide rod.