JPH06265677A - Light water cooled reactor - Google Patents

Abstract

PURPOSE:To make the execution of regular inspection at welding parts and the like easy by arranging an isolation wall between the lower part of a reactor container and the lower part of a reactor pressure vessel for storing pool water at the upper part and forming drywell at the lower part. CONSTITUTION:An isolation wall 31 is arranged between the lower part of a reactor container 21 and a water seal tank 24 or between the lower part of the containment 21 and the lower part of a reactor pressure vessel 1 so as to separate an annular space up and down. At the boundary of spherical wall 21a and cylindrical wall 21b of the containment 21, the wall is formed annularly in the way a part of the spherical wall 21a is extended inside. Above the isolation wall 31, pool water W is stored and a drywell 32 is formed below. By constituting this way, in executing maintenance of the pressure vessel 1 in a regular inspection and the like, by opening an opening cover in the component introduction hatch 33, a worker can easily go inside a containment 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light water cooling type nuclear reactor, and more particularly to a technique for placing a reactor pressure vessel in pool water in a submerged state.

[0002]

2. Description of the Related Art FIG. 4 shows Japanese Unexamined Patent Publication No. Hei 3-252593 (fuel assembly exchange device), Japanese Unexamined Patent Publication No. 3-252594 (fuel assembly exchange device), Japanese Unexamined Patent Publication No. Hei 3-25259.
5 shows an example of a light water cooled nuclear reactor described in Japanese Patent Publication No. 5 (fuel assembly exchange device).

In FIG. 4, reference numeral 1 is a reactor pressure vessel,
2 is a core, 3 is a steam generator, 6 is a primary cooling water pump, 1
Reference numeral 5 is a riser pipe, 16 is a poison tank, 17 is a cooling water inlet, 18 is a water pressure operated valve, 19 is a poison distributor, 20 is a core support plate, and P is boric acid water (pool water in the reactor).

In the nuclear reactor having such a structure, the primary cooling water and the boric acid water P flow differently (circulate) as described below depending on the difference between the operation and the stop of the pump.

During operation, the primary cooling water passes through the core 2, the riser pipe 15, the primary cooling water pump 6, the steam generator 3, and the cooling water inlet 17, as shown by the solid arrow in FIG. However, the boric acid water P is isolated by the hydraulically operated valve 18 and the poison distributor 19 to prevent the phenomenon of insertion and the phenomenon of mixing.
Therefore, the steady operation state is maintained without changing the boric acid water concentration in the primary cooling water.

When the primary cooling water pump 6 is stopped, the steam generator 3 is not fed, and when the discharge pressure drop of the primary cooling water pump 6 is detected, the hydraulically operated valve 18 opens the pipeline. In addition, since the primary cooling water continuously heated in the core 2 rises, the raised primary cooling water is sent out to the inside of the poison tank 16 as shown by a dashed arrow in FIG. The boric acid water P flows into the core 2 via the poison distributor 19 and the concentration of boric acid in the core 2 increases, whereby the fission reaction is suppressed and the suspension is led to a natural stop.

In the reactor shown in FIG. 4, the inside and outside of the poison tank 16 are surrounded by the primary cooling water at a high temperature, and when the output of the reactor changes, the boric acid water P The amount of liquid changes due to expansion and contraction, and therefore, the boundary between the primary cooling water and the boric acid water P easily changes in the portion of the poison distributor 19 and the controllability of the reactor output is likely to be impaired.

Next, FIG. 5 shows another structural example (plan example) of the light water cooling type reactor. In the plan example, the reactor pressure vessel 1 is placed in the pool water W of the reactor containment vessel 21 in a state of being immersed in water, and the poison tank 22 is also placed in the pool water W. And the reactor pressure vessel 1
And the poison tank 22 are connected by a pressure equalizing pipe 23a and a liquid supply pipe 23b which constitute the liquid supply system pipe 23. With this structure, the poison tank 22 is housed in the pool water W in a low temperature state, and is thermally isolated from the reactor pressure vessel 1, and the primary cooling water and the boric acid water P are contained.
It is possible to bring the reactor into a natural shutdown state by supplying the boric acid water P using the drop and the specific gravity difference, and to increase the capacity of the boric acid water P to a large capacity. .

[0009]

However, in the reactor shown in FIG. 5, the pool water W intervenes around the reactor pressure vessel 1, so that the radiation dose is particularly large in the portion. That is, when attempting to carry out a periodical inspection of the lower side wall and the like of the reactor pressure vessel 1 located near the core 2, all pool water W is discharged to create an atmosphere in the vicinity thereof, Alternatively, an inspection underwater is necessary, which requires a great deal of labor. And the reactor pressure vessel 1
The watertight tank 24 and heat insulating material 25
Are arranged to suppress heat exchange between the reactor cooling water inside the reactor pressure vessel 1 and the pool water W. However, the presence of the watertight tank 24 and the heat insulating material 25 also causes a periodic inspection. This is one of the causes of a decrease in workability.

The present invention effectively solves the above problems and facilitates the periodic inspection of welded parts in a reactor pressure vessel, and the reactor pressure vessel and the reactor containment vessel in the vicinity of the core. The objective is to simplify the heat-shielding structure and prevent heat exchange between the reactor cooling water and pool water.

[0011]

[Means for Solving the Problems] Several means for solving the problems are proposed. A first means is a light water cooling type reactor in which the reactor pressure vessel is immersed in pool water of the reactor containment vessel between a lower part of the reactor containment vessel and a lower part of the reactor pressure vessel. , A structure in which an isolation wall that stores pool water above and forms a dry well below is disposed. The second means adds to the first means a structure in which the isolation wall is arranged between the watertight container surrounding the heat insulating material around the reactor pressure vessel and the lower portion of the reactor containment vessel. In the third means, in addition to the first means, an equipment carry-in hatch which penetrates the watertight container and is located below the isolation wall is arranged below the reactor containment vessel. The fourth means is the second means or the third means,
A configuration in which a device transport path is arranged on the inner surface of the watertight container in the dry well is added.

[0012]

In the first means, pool water is stored above the isolation wall, and the reactor pressure vessel is kept in a water immersion state, but below the isolation wall, the area around the reactor pressure vessel is As a dry well, the maintainability around the reactor pressure vessel near the core is improved. In the second means, in addition to the function of the first means, the lower part of the reactor containment vessel and the lower part of the reactor pressure vessel are partitioned by a watertight container, and the area around the watertight container is This is a dry well, and the amount of heat exchange between the reactor cooling water and the pool water in this vicinity is reduced. In the third means, in addition to the function of the first means, the outside of the reactor containment vessel and the inside of the watertight vessel are connected to each other via the equipment carry-in hatch, and the reactor pressure is applied from the outside. Inspection equipment is brought in near the surface of the container. In the fourth means, in addition to the action of the second means or the third means, the equipment transport path arranged on the inner surface of the watertight container allows the inspection equipment along the surface of the reactor pressure vessel to be installed. The move will be implemented and the maintainability of the reactor will be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a light water cooling type nuclear reactor according to the present invention will be described below with reference to FIGS. Also in this embodiment, the pool water W in the reactor containment vessel 21
Is applied to a light water cooling type reactor in which the reactor pressure vessel 1 is placed in a submerged state. In each drawing, reference numeral 31 is an isolation wall, 32 is a dry well, 33 is an equipment carry-in hatch, 34
Is the equipment transport path.

As shown in FIG. 1, the isolation wall 31 is provided between the lower part of the reactor containment vessel 21 and the watertight tank 24, or between the lower part of the reactor containment vessel 21 and the lower part of the reactor pressure vessel 1. And is arranged so as to divide the annular space into upper and lower parts. In the example of FIG. 1, the boundary between the spherical wall 21a and the cylindrical wall 21b in the reactor containment vessel 21 is formed annularly with a part of the spherical wall 21a extended inward.

Pool water W is stored above the isolation wall 31, and a dry well 32 is formed below it. In the example of FIG. 1, the dry well 32 is arranged so as to form an annular space between the cylindrical wall 21b of the reactor containment vessel 21 and the watertight tank 24. Instead, an air atmosphere is used.

As shown in FIG. 2, the equipment carry-in hatch 33 penetrates the cylindrical wall 21b, the dry well 32, the watertight tank 24, and the heat insulating material 25 of the reactor containment vessel 21 and the isolation wall. It is arranged so as to be located below 31. The equipment carry-in hatch 33 includes a horizontal sleeve 33a attached to the cylindrical wall 21b,
Bellows 33b arranged to connect between the cylindrical wall 21b and the watertight tank 24 at an inner position of the horizontal sleeve 33a, and the horizontal sleeve 33a and the bellows 33.
carry-in hole 33c formed by b and the horizontal sleeve 3
Opening / closing cover 33 for opening / closing the outer opening of 3a
d, and a scaffold 33e arranged near the inner bottom surfaces of the horizontal sleeve 33a and the bellows 33b.

The equipment transport path 34 is provided with a dry well 32.
2 and FIG. 3, within the range, the watertight tank 24 is integrally arranged in the vertical and horizontal directions or in a desired direction so as to project from the heat insulating material 25.

In the light water cooling type reactor having such a structure, the pool water W is isolated by the isolation wall 31, and the isolation wall 31
Since the dry well 32 is formed between the watertight tank 24 and the cylindrical wall 21b of the reactor containment vessel 21 in a portion below the dry containment vessel 21, a worker can enter the dry well 32. That is, in the vicinity of the core 2, the dry well 32 is formed around the watertight tank 24 so that the outer surface of the watertight tank 24 is exposed, and the vicinity of the reactor pressure vessel 1 and the core 2 is exposed. The maintainability of the watertight tank 24 or the cylindrical wall 21b is improved.

When the dry well 32 is formed, the heat insulating property is improved as compared with the case where the pool water W enters into that portion, and the amount of heat released from the reactor pressure vessel 1 is reduced, The heat of the nuclear reactor is effectively used, and the heat insulating material 25 in this range can be simplified.

At the time of periodic inspection, etc., the reactor pressure vessel 1
When carrying out maintenance of the
By opening the opening / closing cover 33d in 3, the worker can enter the inside of the reactor containment vessel 21.
By using the scaffold 33e to carry in the inspection equipment and the like into the watertight tank 24, support the inspection equipment and the like by the equipment conveyance path 34, and move them to various places in the reactor pressure vessel 1, desired maintenance can be performed. Will be implemented.

[Other Embodiments] In the light water cooling type reactor according to the present invention, the following technique can be adopted instead of one embodiment. a) Manholes, hatches, etc. for workers to enter in the dry well 32 should be provided in combination with the installation of the equipment carry-in hatch 33. b) When the isolation wall 31 has a structure that does not penetrate the watertight tank 24, the equipment transport path 34 should be extended to a position above the isolation wall 31. c) The equipment transport path 34 is laid and connected to the scaffold 33e in the equipment carry-in hatch 33.

[0022]

The light water cooled nuclear reactor according to the present invention has the following effects. (1) An isolation wall is provided between the lower part of the reactor containment vessel and the lower part of the reactor pressure vessel, and a dry well is formed below the isolation wall to allow workers to enter the reactor containment vessel. And equipment can be carried in, and the maintainability of the reactor can be improved. (2) The isolation wall is arranged between the watertight container and the lower part of the reactor containment vessel to facilitate the formation of dry wells by utilizing the airtightness of the watertight container and to cool the reactor cooling water in this part. It is possible to improve the thermal efficiency of the nuclear reactor and to simplify the heat insulating structure by hindering the heat exchange between the water and the pool water. (3) By arranging the equipment carry-in hatch under the watertight container in the lower part of the reactor containment vessel, it becomes easy to carry in the inspection equipment around the reactor pressure vessel, and the workability of periodic inspection etc. Can be improved. (4) By arranging the equipment transport path on the inner surface of the watertight container, the inspection equipments can be easily moved along the surface of the reactor pressure vessel, and the reactor can be efficiently maintained.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a light water cooling-type nuclear reactor according to the present invention.

FIG. 2 is an enlarged view of a device carrying-in hatch portion shown in FIG.

FIG. 3 is a perspective view of a device transport path portion in the example of FIG.

FIG. 4 is a front sectional view showing a conventional example of a light water cooling reactor.

FIG. 5 is a front cross-sectional view showing a plan example of a light water cooling reactor.

[Explanation of symbols]

 1 Reactor pressure vessel 2 Core 3 Steam generator 6 Primary cooling water pump 21 Reactor containment vessel 21a Spherical wall 21b Cylindrical wall 22 Poison tank 23 Liquid supply piping 23a Pressure equalizing piping 23b Liquid supply piping 24 Watertight tank 25 Insulation Material 31 Isolation wall 32 Drywell 33 Equipment carry-in hatch 33a Horizontal sleeve 33b Bellows 33c Carry-in hole 33d Open / close cover 33e Scaffold 34 Equipment transport path P Boric water (pool water in reactor) W Pool water

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location 8908-2G G21C 13/02 GDL Q

Claims (4)

[Claims] 1. A light water cooled reactor in which the reactor pressure vessel is submerged in the pool water of the reactor containment vessel, and between the lower part of the reactor containment vessel and the lower part of the reactor pressure vessel. A light water cooled nuclear reactor, characterized in that an isolation wall for storing pool water in the upper part and forming a dry well is arranged in the lower part. 2. The light water cooled atom according to claim 1, wherein the isolation wall is arranged between a watertight container surrounding a heat insulating material around the reactor pressure vessel and a lower portion of the reactor containment vessel. Furnace. 3. The light water cooling type atom according to claim 1, wherein an equipment carry-in hatch penetrating the watertight container and located below the isolation wall is arranged in a lower portion of the reactor containment vessel. Furnace. 4. The light water cooling type nuclear reactor according to claim 2 or 3, wherein an equipment transport path is arranged on the inner surface of the watertight container in the dry well.