JPH08313677A - Reactor well seal structure - Google Patents

Abstract

PURPOSE: To facilitate cleaning and inspecting well seal by constituting a basin seal with a structure standing from the upper main body of a reactor pressure vessel(RPV) and correcting a refueling bellows to the upper surface of the basin seal. CONSTITUTION: Among the inner well seal 3, a bracket form 5 and a refueling bellows 7 is positioned higher than RPV main body upper part 2 and containment (PCV) main body upper part 1. That is, a basin seal 12 is constituted of a lower flange 12a extending outward from the RPV main body upper part 2, a cylindrical part 12b standing outside of it and connected and an upper flange 12c extending outward from the top end. Thus, its cross section has a shape of a crank. The upper surface of the upper flange 12c is almost in the same elevation as the upper surface of the RPV main body upper part 2. The refueling bellows 1 is positioned higher than the RPV main body upper part 2 in such a way and the gap to RPV upper lid a2 is large and so cleaning and inspection of bellows inner surface is easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a well seal structure for a nuclear reactor, and more particularly to a well seal structure for a nuclear reactor which is easy to maintain.

[0002]

2. Description of the Related Art FIG. 3 is a front sectional view showing an entire nuclear reactor.
is there. In the figure, a is a reactor pressure vessel (hereinafter referred to as RPV).
Thus, the fuel rod is housed in the container. RPVa is pressure
Body a ₁And lid a₂The replacement of fuel rods is
₂Remove and perform. b is a nuclear reactor containing the RPV
It is a container (hereinafter referred to as PCV) and has a cylindrical shape inside.
There is a pedestal h, a diaphragm floor e, etc.
And RPVa is installed on the pedestal. Diamond
The inside of the PCV is vertically divided by the flam floor e.
Part is dry well d, lower part is suppression chamber f
Is. PCVb is the main container b₁And lid b₂And more
And the fuel rod replacement is the upper lid b₂Remove and perform. c is
Steel plate concrete reactor building containing PCV (hereinafter
It is called the SC building). PCV body b₁R at the top
PV body a₁Well between the upper part and the SC building
A seal g is provided. PC out of Welseal g
V body b₁Upper part and RPV body a₁Provided between the upper part
Inner well seal g₁, PCV body b₁On top
Outer well seal installed between SC building c
g₂Say.

The fuel rods are exchanged by removing the RPV upper lid a ₂ and the PCV upper lid b ₂ and then filling the RPV main body a ₁ and the PCV main body b ₁ with water. A well seal g is provided in a watertight manner so as not to flow down into the gap between the main body b ₁ and the SC building c. Since the well seal g is attached as it is during the reactor operation, it absorbs the difference in thermal expansion between the RPV main body a ₁ and the PCV main body b ₁ and between the PCV main body b ₁ and the SC building c. Needed, each with bellows.

FIG. 2 is a side sectional view of a conventional reactor well seal. In the figure, reference numeral 1 is an upper portion of the PCV main body b ₁ , and a main flange 1a for connecting to the upper lid b ₂ is attached to the top of the main body. 2 is the upper part of the RPV body a ₁ and the RPV is on the upper surface
Place the upper lid a ₂ and tighten it with a stud bolt (not shown). 3 is an inner well seal and a well platform 5
, Basin Seal 20 and Well Platform 5
And basin seal 20 can be moved vertically relative to each other,
And a fuel exchange bellows 7 which is watertightly connected. The well platform 5 is horizontal and has an annular upper plate 5a, ribs 5b radially welded to the lower surface of the upper plate 5a at equal intervals in the circumferential direction, and lower plate 5c having a reverse T-shaped cross section welded to the lower surface of the rib 5b. Consists of. Well platform 5 is PCV
PCV on the outer circumference so that it extends horizontally from the upper part 1
It is welded to the inner surface of the upper part 1.

The basin seal 20 is a member whose cross section is bent into a crank shape as shown in the figure, and is the upper part 2 of the RPV body.
Inner flange 20a protruding from the outside and welded
A cylindrical member 20b attached downward from the tip of the inner flange 20a, and an outer flange 20c attached so as to project outward from the lower end of the cylindrical member 20b.
Consists of The drain pipe 10 is provided on the outer flange 20c.

The fuel exchange bellows 7 includes a member 7a fixed to the well platform 5 and a basin seal 20.
And a bellows 7c that connects the members 7a and 7b in a watertight manner and is movable in the vertical direction. The bellows is made of thin stainless steel plate. Member 7
a is an annular flat plate 7d welded to the well platform upper plate 5a and a cylindrical member 7 welded to the flat plate 7d.
e, an annular flat plate 7f projecting inwardly and welded to the upper end of the cylindrical member 7e, a cylindrical member 7g welded to the lower surface of the flat plate 7f, and an annular flat plate 7h welded to the outer surface of the cylindrical member 7g. And a seal member 7i attached to the outer surface of the lower end of the cylindrical member 7h and having an inverted U-shaped cross section, and a flat plate 7j having one end welded to the outer surface of the cylindrical member 7e and the other end welded to the rib 5b of the well platform 5. .

The member 7b is a cylindrical member 7k welded to the upper surface of the outer flange 20c of the basin seal 20, and an annular flat plate 7r welded to the upper outer surface of the cylindrical member 7k.
It is composed of a cylindrical member 7m welded to the outer periphery of the flat plate 7r, and a member 7q attached to the inner surface above the cylindrical member 7k. A bellows 7c is attached in a watertight state between the lower end of the cylindrical member 7g and the upper end of the cylindrical member 7k. A cover 7p is provided inside the bellows 7c. Cover 7p
The upper end of is fixed to the flat plate 7f with bolts. The upper surface of the cylindrical member 7m is in sliding contact with the outer end of the flat plate 7h, and the outer surface of the lower end of the cover 7p is in slidable contact with the member 7q.

A seal breakage drain 7 is provided below the cylindrical member 7m.
n is installed. The cover 7p is provided to protect the bellows 7c when water is filled above the well seal. The cylindrical member 7m and the seal member 7i are provided as guards for preventing a large amount of water from flowing into the dry well d should the bellows 7c break.

Reference numeral 4 denotes an outer well seal, which is an annular flat plate 6 welded to the outer peripheral surface of the PCV main body upper portion 1 and a steel annular member 11 having a box-shaped cross section welded to the inner surface of the SC building c.
And a well seal bellows 8 for welding the flat plate 6 and the annular member 11 so as to be relatively movable in the vertical direction. A drain pipe 9 is provided on the flat plate 6.

The well seal bellows 8 is a member 8a fixed to the annular member 11 and a member 8b fixed to the flat plate 6.
And a bellows 8c connecting the members 8a and 8b so as to be relatively movable in the vertical direction. The member 8a is formed on the upper surface of the annular member 11 by an annular flat plate 8e which is projected and welded inward, and a cylindrical member 8f which is welded to the inner peripheral end of the flat plate 8e.
And a cover 8d whose upper end is fixed by a bolt and which is provided inside the bellows 8c to protect the bellows 8c. The member 8b is a ring-shaped flat plate 8g which is projected and welded to the upper surface of the flat plate 6, a cylindrical member 8h which is erected on the upper surface of the flat plate 8g and is welded, and a member 8i which is projected and welded inward from the cylindrical member 8h. Consists of. A bellows 8c is attached between the lower end of the cylindrical member 8f and the upper end of the cylindrical member 8h. The lower end of the cover 8d is in sliding contact with the member 8i. Incidentally P
Since there is no important device between the CV body b ₁ and the SC building c, there is no guard (members corresponding to the members 7m, 7i of the fuel exchange bellows 7) when the well seal bellows 8 is broken.

[0011]

The conventional well seal structure described above, particularly the inner well seal, has the following problems. (1) Water is filled to replace the fuel rods, and water is drained after completion, but there are impurities in the water, so cleaning must be performed after draining. Especially since the bellows has many folds, it takes time to clean. Also, since the bellows is a thin plate, it must be inspected for any damage such as holes. At this time, the gap between the fuel exchange bellows 7 and the basin seal 20 is narrow, and cleaning and inspection are not easy even if the cover 7p is removed. (2) The height of the main flange 1a is the RPV upper lid a ₂
Since it has almost the same height as the upper surface of the flange and has a height difference of 1 m from the upper surface of the well platform 5, the accessibility for cleaning and inspection is poor.

The present invention has been devised in view of the above problems, and an object thereof is to provide a well seal structure for a nuclear reactor that is easy to clean and inspect and has good passage.

[0013]

In order to achieve the above object, a well seal structure for a reactor according to the present invention comprises an upper part of a main body of a reactor containment vessel and an upper part of a main body of a reactor pressure vessel housed in the reactor containment vessel. The inner well seal of the reactor, which is capable of absorbing the difference in thermal expansion and is watertight, and the upper part of the main body of the reactor containment vessel and the steel plate concrete reactor building are capable of absorbing the difference in thermal expansion and are watertight. In the well seal structure of the reactor consisting of the outer well seal to be connected, the inner well seal is an annular well platform that horizontally extends inward from the upper part of the reactor containment vessel main body and the outer well seal from the upper part of the reactor pressure vessel main body. A basin seal protruding toward one side, and a fuel exchange bellows that connects the upper surface of the basin seal and the well platform in a vertically movable manner and is watertight. Becomes, basin seal includes a cylindrical member connected to ramps up from the outer end of the lower flange and lower flange projecting outwardly from the reactor pressure vessel upper main body,
It consists of an upper flange protruding outward from the upper end of the cylindrical member, and the upper flange is substantially level with the upper surface of the reactor pressure vessel body.

[0014]

The basin seal is structured so that it rises from the upper part of the RPV main body so that its upper surface is almost level with the upper surface of the RPV main body, and the fuel exchange bellows is connected to the upper surface of the basin seal. There is enough clearance for access. Further, the height of the well platform is also increased accordingly, so that the step difference from the main flange of the PCV is reduced and the passage is improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The present invention relates to a partial improvement of the well seal of the related art described above, and the same parts as those of the related art are designated by the same reference numerals, and the duplicated description will be omitted.

FIG. 1 is a front sectional view of a reactor well seal structure of the present invention. In the figure, 3 is an inner well seal and 4 is an outer well seal. The outer well seal 4 is the same as the conventional one except that its position is higher in relation to the upper portion 1 of the PCV body. The inner platform 5 of the inner well seal 3 and the fuel exchange bellows 7 are the upper part 2 of the RPV body,
It is the same as the conventional one except that the position is higher in relation to the upper portion 1 of the V body.

Therefore, the basin seal 1 is different from the conventional one.
2 and will be described in detail below. Basin Seal 1
Reference numeral 2 is composed of a lower flange 12a protruding outward from the upper part 2 of the RPV body, a cylindrical member 12b connected to rise from the outer end of the lower flange 12a, and an upper flange 12c protruding outward from the upper end of the cylindrical member 12b. ing. Therefore, the cross section is bent into a crank shape as shown in the figure. The upper surface of the upper flange 12c is the upper portion 2 of the RPV body.
It has almost the same height as the upper surface. The height may be slightly higher or lower within a range where the refueling bellows 7 can be easily accessed. Further, the drain pipe 10 is provided near the lower end of the cylindrical member 12b.

As described above, the fuel exchange bellows 7 is located above the RPV main body upper portion 2, and the gap between the fuel exchange bellows 7 and the RPV upper lid a ₁ is sufficiently large, so that the inner surface of the bellows can be easily cleaned and checked. Further, the height of the well platform is close to that of the main flange 1a, so that the accessibility for inspection and cleaning is significantly improved.

[0019]

As described above, the well seal structure of the nuclear reactor of the present invention has the following effects because the basin seal is provided so as to stand up from the upper part of the RPV body. (1) The refueling bellows, which has been the most difficult to clean and inspect in the past, is now located above the RPV main body,
The gap for cleaning / inspection becomes large and cleaning / inspection becomes easy. (2) Since the position of the well platform is close to the height of the PCV main flange, passage to the inside of the PCV is significantly improved.

[Brief description of drawings]

FIG. 1 is a front sectional view of a well seal structure for a nuclear reactor of the present invention.

FIG. 2 is a front sectional view of a conventional well seal structure for a nuclear reactor.

FIG. 3 is a front sectional view showing the entire nuclear reactor.

[Explanation of symbols]

 1 Reactor containment vessel (PCV) main body upper part 2 Reactor pressure vessel (RPV) main body upper part 3 Inner well seal 4 Outer well seal 5 Well platform 7 Fuel exchange bellows 12 Basin seal c SC building 12a Lower flange 12b Cylindrical member 12c Upper flange

Claims (1)

[Claims] 1. An inner well of a reactor for connecting the upper part of the main body of the reactor containment vessel and the upper part of the main body of the reactor pressure vessel housed in the reactor containment vessel in a watertight manner capable of absorbing a difference in thermal expansion. In the well seal structure of the reactor consisting of a seal and an outer well seal that connects the upper part of the main body of the reactor containment vessel and the steel plate concrete reactor building in a watertight manner so as to absorb the difference in thermal expansion, the inner well seal is , An annular well platform that horizontally extends inward from the upper part of the reactor containment vessel main body, a basin seal protruding outward from the upper part of the reactor pressure vessel main body, and the basin seal upper surface and the well platform are vertically opposed to each other. It consists of a refueling bellows that is movably and watertightly connected.The basin seal is a lower flap that extends outward from the upper part of the reactor pressure vessel body. It consists of a cylindrical member that rises from the outer end of the flange and is connected to the lower flange, and an upper flange that projects outward from the upper end of the cylindrical member, and the upper flange is approximately level with the upper surface of the reactor pressure vessel body. A well seal structure for a nuclear reactor characterized by the following.