JPH0746155B2 - Stud bolt protector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of use) The present invention is directed to damage of a stud bolt erected on the upper flange surface of a reactor pressure vessel of a boiling water reactor when exposed. The present invention relates to a stud bolt protection device that prevents the
(Prior Art) In a boiling water nuclear reactor, as shown in FIG. 5, a reactor core 2 is housed in a reactor pressure vessel 1, and an end plate above a shroud 3 surrounding the reactor core 2 is connected to a stand pipe. 4 is erected and connected to a steam separator 5 to form a shroud head 6. A steam dryer 7 is arranged further above the steam separator 5. The mixed flow of water and steam generated in the reactor core 2 enters the steam-water separator 5 through the stand pipe 4, and the steam subjected to the first stage moisture separation is steam together with the remaining saturated water. It is sent to the drier 7 to be further separated from moisture, and sent from the main steam pipe 8 to a turbine (not shown).

At the time of periodical inspection of the reactor, the upper lid 9 of the reactor pressure vessel 1 is removed in order to exchange the fuel loaded in the core 2, and the steam dryer 7 and the shroud head 6 are stored in a storage place outside the reactor pressure vessel 1. Transfer to. The steam dryer and steam separator suspenders used at this time (hereinafter referred to as DS sling)
g)) 11 is a steam dryer 7 as shown in FIG.
A hook 12 with a cross-shaped beam 13 having a socket 12 connected to a hanging ear 10 provided at the top of the
It is suspended from a suspension wire 15 from 14, and is used by being attached to an overhead crane installed in the reactor building.

When the steam dryer 7 or the shroud head 6 suspended by the DS sling 11 is carried in and out of the reactor pressure vessel 1, these devices are kept in an appropriate positional relationship with the reactor pressure vessel 1 and contacted with each other. , A guide rod 16 is provided in the vertical direction along the inside of the side wall of the reactor pressure vessel 1 so as not to collide with each other and damage each other (see FIG. 5),
The groove of the placket 17 provided on the outer side of the steam dryer 7 or the shroud head 6 is fitted and inserted in this, and guided by sliding (see FIG. 7).

The details of the guide rod 16 are, as shown in FIG. 8, a guide rod bracket provided inside the side wall 18 near the flange surface 19 forming the upper end of the side wall 18 of the reactor pressure vessel 1 from which the upper lid 9 is removed. 20, the tube portion that is the main body of the guide rod 16
21 is screwed and fixed by the top stud 22, and the pipe section
The lower end of 21 is loosely fitted in the hole of the guide pin bracket 23 extending from the upper end of the shroud 3 to absorb the difference in thermal expansion.

Stud bolts 24 for fixing the upper lid 9 are planted on the flange surface 19.

(Problems to be Solved by the Invention) The above-described transfer of the steam dryer 7 or the shroud head 6 is preferably carried out in a submerged state because these devices are radioactive, but DS Sling 11
May dislike being submerged in water, and for example, the steam dryer 7 may be transferred into the air.

At this time, as shown in FIG. 9, the worker 26 located on the operation floor 25 in order to reduce the exposure dose is
While monitoring the reactor pressure vessel 1 located 9 m below, the transfer work of the steam dryer 7 suspended from the DS sling 11 is being carried out. When carrying in, mount the bracket 17 to the guide rod.
Bracket 17 when guiding to 16 and when carrying out
There is a stud bolt 24 projecting from the flange surface 19 at a close position immediately after the rod escapes from the guide rod 16. Therefore, pay close attention to avoid contact with the stud bolt 24 and carry out the transfer work of the steam dryer 7. It was necessary, and the radiation dose tended to increase as the working time increased.

An object of the present invention is to install a steam separator and a steam dryer that are carried in and out of a reactor pressure vessel of a boiling water reactor, on the upper flange surface of the reactor pressure vessel with the upper lid removed. Another object of the present invention is to provide a stud bolt protection device capable of preventing the stud bolt from coming into contact with and damaging the stud bolt.

[Structure of the Invention] (Means for Solving Problems) In the present invention, as a stud bolt protection device, a temporary fixing is performed by engaging with a stud bolt planted on the upper surface of the flange of the reactor pressure vessel. A member and a guide member held by the fixing member and occupying an upward extension of a guide rod provided inside the side wall of the reactor pressure vessel are provided.

(Function) The groove of the bracket, which is hung from above the reactor pressure vessel and is provided on the outside surface of the in-reactor equipment that is carried in and out of the reactor pressure vessel, engages with the tip of the guide member during loading. After the fitting, the guide rod is guided by the guide rod following the guide member, and is guided until the tip of the guide member is removed at the time of carrying out, so that the bracket does not interfere with the stud bolt.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In FIGS. 1 and 2, a large number of stud bolts 24 are erected at regular intervals on a flange surface 19 forming the upper end of the side wall 18 of the reactor pressure vessel with the upper lid removed.
A guide rod bracket 20 is provided inside the side wall 18 (on the right side in FIG. 1), and a top stud 22 forming the tip of the guide rod 16 is provided above the guide rod bracket 20. The guide rods 16 are provided inside the side wall 18, for example, at two places,
The figure shows one of them.

Two adjacent stud bolts closest to the guide rod 16
A cylindrical support cap 27 is attached to each 24. The entire length of the support cap 27 is the same as the height of the stud bolt 24 to be attached. Top studs
22 (having the same outer diameter as the tube portion 21 of the guide rod 16),
A cylindrical guide cap 28, for example, is attached on the upper extension thereof. The upper end of the guide cap 28 is gradually reduced in diameter and the end is formed in a round cap shape. The guide cap 28 is connected to and supported by the respective support caps 27 and the connectors 29 at the upper and lower portions thereof.

The details of the connector 29 are shown in FIG. 3 which is an enlarged view of the portion A in FIG. 1. As shown in FIG. It is sandwiched by two plates 33 provided with 32, and bolts 34 and nuts 35 through which the long holes 30, 32 are inserted.
Fastened by the support cap 27 and the guide cap
It is adapted to support the space between 28.
FIG. 4 shows a sectional view taken along the line BB of FIG.

Next, the operation of this will be described.

When suspending a shroud head having an outer diameter that is almost the same as the inner diameter of the reactor pressure vessel, or a steam dryer, etc., inside the reactor pressure vessel, the groove of the bracket provided on the outer side of these equipment should be installed on the guide rod 16. Although it is inserted and guided,
According to this embodiment, the groove of the descending device bracket is first engaged with the tip of the guide cap 28, and then guided along the guide cap 28 to the guide rod 16. Since the tip of the guide cap 28 is provided at approximately the same height as the stud bolt 24, the suspended device may swing before the bracket groove engages with the guide cap 28. However, there is no possibility of contacting the stud bolt 24 and damaging it.

Further, when the above-mentioned equipment in the reactor pressure vessel is lifted and taken out, the groove of the bracket is guided by the guide cap 16 and the guide cap 28, so that the equipment hung after removing the guide cap 28 Even if it swings, there is no possibility of contacting the stud bolt 24 and damaging it.

When the support cap 27 is pulled out from the stud bolts 24 and the protective device is removed after the equipment has been loaded, the upper lid of the reactor pressure vessel can be attached.

It should be noted that the connector 29 may be provided only at one place on the lower part. The outer diameter of the guide cap 28 does not necessarily have to be the same as that of the guide rod 16, and may be slightly larger than this.

[Advantages of the Invention] According to the present invention, when a shroud head, a steam dryer, or the like is carried in and out of a reactor pressure vessel, there is no opportunity for these devices to come into contact with stud bolts to cause damage or the like. As a result, the transfer work is facilitated and the work time is shortened. As a result, the radiation exposure dose of the worker is also reduced.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention, and FIG.
FIG. 3 is a top view of the drawing, FIG. 3 is a side view showing in detail an enlarged portion A of FIG. 1, and FIG.
Fig. 5 is a sectional view showing the outline of the reactor pressure vessel, and Fig. 6 is
FIG. 7 is a perspective view showing a DS sling, FIG. 7 is a top view showing a relative positional relationship between a steam dryer and a shroud head with respect to a reactor pressure vessel, FIG. 8 is a cross-sectional view showing a mounting state of a guide rod, and FIG. 9 is steam. It is a schematic diagram which shows the transfer condition of a dryer. 1 …… Reactor pressure vessel, 16 …… Guide rod 18 …… Sidewall, 19 …… Flange surface 24 …… Stud bolt, 27 …… Support cap 28 …… Guide cap

Claims (2)

[Claims] 1. A fixing member that is temporarily installed by engaging with a stud bolt that is erected on the upper surface of a flange of a reactor pressure vessel,
A stud bolt protection device, comprising: a guide member which is held by the fixing member and which occupies an upward extension of a guide rod provided inside the side wall of the reactor pressure vessel. 2. The stud bolt protection device according to claim 1, wherein the tip portion of the guide member is extended to the same level as the tip portion of the stud bolt.