JPH0295299A - Nuclear reactor containment - Google Patents

Abstract

PURPOSE:To speedily and stably cool the containment for a long period after a cooling material losing accident by consisting an outer peripheral containment pool of small-sized section outer peripheral containment pools. CONSTITUTION:The outer peripheral containment pool 48 consists of the small- sized section outer peripheral containment pools 49 which are arranged in the height direction and circumferential direction of the external wall of the containment 46 and the water in an upper water supplement pool 50 is supplied to the section outer peripheral pools 49 through water supplement pipe 51, water supplement branching pipes 52, and a float valve 53 to secure a constant pool water level 54. Further, the section outer peripheral pools 49 are open to the air through an atmospheric vent pipe 55 and the water temperature of the section outer peripheral pools 49 is limited to 100-110 deg.C. Then, heat generated in the containment 46 is conducted to the wall of the containment 46 and further conducted to the water in the outer peripheral pool 48. In the outer peripheral pool 48, a natural circulation flow is generated and boiling is caused in the internal wall of the pool to cool the containment 46 with the boiling latent heat.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a reactor containment vessel for a boiling water reactor (hereinafter referred to as BWR), and in particular to a reactor containment vessel in the event of a loss of coolant accident. Concerning improvement of container cooling structure.

(Prior Art) FIG. 9 is a schematic diagram showing main components of a cooling system of a reactor containment vessel in a conventional BWR. Reactor pressure vessel 1
A reactor containment vessel 2 that houses high-pressure piping for the primary system is divided into upper and lower parts by a diaphragm floor 3. The upper part of the containment vessel 2 is called a dry well 4, and the lower part is called a wet well 5. A pressure suppression chamber 6 is provided in the wet well 5 and holds a large amount of cooling water. During normal operation, the inside of the containment vessel is cooled by the dry well cooler. When the high pressure piping of the reactor primary system ruptures and coolant spouts into the dry well 4, such as in a loss of coolant accident (LOCA), the coolant is guided into the pressure suppression chamber 6 through the vent pipe 8, Condensed by cooling water. At the same time, the containment vessel spray 11 is operated by the low-pressure water supply pump 10 powered by the emergency diesel generator, and the steam in the dry well is condensed and cooled. The water temperature in the pressure suppression chamber 6 gradually rises due to decay heat released into the dry well 4 by emergency core cooling water from the reactor 1. For this reason, the containment vessel spray 11 is performed using a low-pressure pump while being cooled by a heat exchanger 12 that exchanges heat with seawater.

In the conventional reactor containment vessel having the above configuration, L
In order to cool the water in the dry well 4 and the pressure suppression chamber 6 during OCA, it is essential that dynamic equipment such as the low-pressure water pump 10 and the heat exchanger 12 operate normally. Attempts have been made to develop more reliable cooling methods that eliminate this constraint. For example, as shown in Japanese Unexamined Patent Publication No. 63-75594, a containment vessel outer circumference boule is provided on the outer circumference of the containment vessel that houses the reactor pressure vessel, and water in the containment vessel outer circumferential pool is heated and evaporated. Accordingly, a natural heat dissipation type reactor containment vessel in which the containment vessel is cooled has been proposed. FIGS. 10 and 11 respectively show conventional reactor containment vessels of this type.

In other words, in the conventional reactor containment vessel shown in FIG. At the same time,
These two wells 23 and 25 are communicated via a steam vent pipe 27, and a containment vessel outer circumference boule 28 is provided on the outer circumference of the containment vessel 26, and this containment vessel outer circumference boule 28 is connected via a float valve 29 to provide upper water supply. It is connected to the boule 30, and the inside of the containment vessel outer circumferential boule 28 is opened to the atmosphere via an atmospheric vent pipe 31.

Furthermore, the conventional reactor containment vessel shown in FIG.
In addition to the configuration of the reactor containment vessel shown in the figure, a heat transfer plate 32 is attached horizontally to the outer wall of the containment vessel 26 facing the containment vessel outer peripheral boule 28.

(Problems to be Solved by the Invention) In the conventional reactor containment vessel shown in FIG. 10, the containment vessel outer perimeter boule 28 has a width W of 1 as shown in FIG.
m or less, the height H becomes 10 to 30 m, resulting in a shape where the height H is higher than the width W, resulting in insufficient natural convection, and the saturation temperature is higher at the bottom due to the water head. .

For this reason, as the water rises, the high temperature water boils under reduced pressure and bumps, which tends to cause unstable flow called Geisering. Further, the conventional containment vessel outer circumferential boule 28 has a problem in that, since there is no partition in the circumferential direction, vortices occur in the circumferential direction and natural convection is likely to be inhibited. Therefore, there is a problem that a stable cooling effect cannot be obtained.

Furthermore, in the conventional reactor containment vessel shown in FIG.
Water in the containment vessel outer circumferential boule 28 evaporates due to heat transfer and bubbles are generated, but since the heat transfer plate 32 is installed horizontally, the bubbles stagnate at the bottom of the heat transfer plate 32, reducing heat transfer efficiency. There is a problem that a bad gas phase is created. Furthermore, since natural convection is obstructed by the heat exchanger plate 32, there is also the problem that cooling efficiency cannot be improved.

The present invention has been made in consideration of these points, and an object of the present invention is to provide a reactor containment vessel that can quickly and stably cool the containment vessel for a long period of time after a loss of coolant accident. shall be.

[Structure of the invention]

(Means for Solving the Problems) As a means for achieving the above object, the first invention of the present invention provides a containment vessel outer periphery boule on the outer periphery of the containment vessel that stores the reactor containment vessel, and this containment vessel outer layer. In a natural heat dissipation type reactor containment vessel in which the containment vessel is cooled by temperature rise and evaporation of water in the pool, a plurality of the containment vessel outer peripheral pools are arranged in a height direction and a circumferential direction of the outer wall of the containment vessel, respectively. It is characterized by being configured with a separate containment vessel and a peripheral pool.

Further, as a means for achieving the above object, a second aspect of the present invention provides, in a reactor containment vessel similar to the above, the inside of the containment vessel is divided into a plurality of small chambers in a radial direction and a circumferential direction in a peripheral pool of the containment vessel. It is characterized by having a wall.

Furthermore, a third invention of the present invention provides, as a means for achieving the above-mentioned object, heat transfer plates are vertically installed on the inner and outer walls of the containment vessel facing the containment vessel outer peripheral pool in the reactor containment vessel similar to the above-mentioned reactor containment vessel. It is characterized in that it is provided.

(Function) In the reactor containment vessel according to the first invention of the present invention,
The containment vessel outer circumferential pool is composed of a plurality of small sectional containment vessel outer circumferential pools. Therefore, the height of the outer circumferential pool of each divided containment vessel can be lowered, and the saturation temperature difference due to the water head is reduced, making it possible to prevent Geisering and improving heat transfer efficiency. In addition, a large amount of heat removal can be achieved because the peripheral pool of the divided containment vessel can also be installed on the outer wall of the dry well.

Furthermore, in the reactor containment vessel according to the second aspect of the present invention, the inside of the outer peripheral pool of the containment vessel is divided into a plurality of small chambers in the radial and circumferential directions by walls, so that heat generation within the containment vessel is prevented. Even if the water becomes uniform, natural circulation of water in the outer circumferential pool of the containment vessel, particularly in the circumferential direction, is prevented, and natural circulation and boiling in the vertical direction are promoted. Therefore, it becomes possible to improve the reliability of cooling. Furthermore, in the reactor containment vessel according to the third aspect of the present invention, heat generation within the containment vessel is transmitted to the containment vessel wall via a heat transfer plate provided on the inner wall of the containment vessel. The heat is transmitted to the water in the outer circumferential pool of the containment vessel through the heat exchanger plate. In the outer pool of the containment vessel, a natural circulation flow occurs with an upward flow on the inner circumference side and a downward flow on the outer circumference side, but since the heat exchanger plate is installed vertically, it can be cooled without interfering with this natural circulation flow. At the same time, the bubbles generated by evaporation are not stagnated by the heat exchanger plate, and the heat exchanger plate also functions as a baffle plate against the natural circulation flow in the circumferential direction. Therefore, highly efficient heat transfer is possible.

(Example) Hereinafter, a first example of the present invention will be described with reference to FIGS. 1 to 5.

In FIG. 1, reference numeral 41 denotes a reactor pressure vessel containing a reactor core 42. This reactor pressure vessel 41 is housed in a dry well 43, and this dry well 43 is a wet well having a pressure suppression pool 44. Together with 45, it constitutes a containment vessel 46. And Drywell 43
and the wet well 45 are connected via a steam vent pipe 47, and a containment vessel outer peripheral pool 48 is provided at the outer periphery of the containment vessel 46 to cool the containment vessel 46 after a coolant loss accident. ing.

As shown in FIGS. 1 and 2, the containment vessel outer peripheral pool 48 is composed of a plurality of small sectional containment vessel outer periphery pools 49 arranged in the height direction and circumferential direction of the outer wall of the containment vessel 46, respectively. The water in the upper replenishment pool 50 is transferred to the outer peripheral pool 49 of the containment vessel through a replenishment pipe 51 and a replenishment branch pipe 52.
and a float valve 53, respectively, to ensure a pool water surface 54 at a constant water level.

In addition, the outer peripheral pools 49 of each divided containment vessel are opened to the atmosphere through the atmospheric vent pipe 55 as shown in FIG.
It is now possible to limit

Next, the operation of this embodiment will be explained.

The heat generated in the containment vessel 46 is transmitted to the walls of the containment vessel 46 and further to the water in the containment vessel outer peripheral pool 48.

A natural circulation flow occurs within the containment vessel outer peripheral boule 48,
Boiling occurs on the inner wall of the pool, and the latent heat of boiling causes the containment vessel 4 to boil.
6 is cooled.

By the way, in this embodiment, the containment vessel outer perimeter boule 4
8 is composed of a plurality of divided containment vessel outer circumferential boules 49, so as shown in FIG. Can be done. Therefore, the saturation temperature difference due to water head is 10℃
It can be made as small as below, and Geisering can be prevented. In addition, the part proportional to the amount of heat removed is indicated by the symbol B1 in Fig. 3.
゜B 2 , . . . is an inclined part indicated with B1,
This corresponds to the shaded area indicated by the symbol A in the conventional example in FIG. As is clear from the comparison of both figures, the amount of heat removed can be increased.

In addition, since the outer circumferential boule 49 of each divided containment vessel is exposed to the atmosphere via the atmospheric vent pipe 55, the water temperature in the outer circumferential boule 49 of each divided containment vessel is 100 to 100% as shown in FIG.
The temperature can be limited to 110°C. For this reason, Figure 4 (
As shown in a) and (b), the internal pressure of the containment vessel 46 is 4.7
At the time of at, the temperature is 130 to 150°C, and the temperature difference between the inside and outside walls of the containment vessel 46 can be as large as 20 to 50°C, and heat transfer can also be increased.

In addition, the partitioned containment vessel outer circumferential boule 49 is connected to the dry well 4
Since it can also be installed on the outer wall of the dry well 43, it is also possible to remove heat from the dry well 43. This not only increases the heat transfer area, but also improves dry well 4, which has low nitrogen partial pressure and high condensation heat transfer.
This means that the large amount of heat removed from the container 46 is added to the amount of heat removed from the containment vessel 46. Because Drywell 4
This is because the nitrogen in the wet well gas phase is pushed out together with steam to the pressure suppression boule 44 through the steam vent pipe 47, and as shown in FIG. 5, the condensation heat transfer coefficient of the wet well gas phase is extremely reduced.

In this way, since the containment vessel outer circumferential boule 48 is composed of a plurality of divided containment vessel outer circumferential boules 49, cooling after a cooling loss accident can be performed for a long period of time without requiring power or operation by an operator. can be stabilized. In addition, the containment vessel 46
Since a large amount of heat can be removed from the reactor, the containment vessel 46 can be made smaller, and the cost of the reactor building can be significantly reduced.

6 and 7 show a second embodiment of the present invention, in which a containment vessel perimeter boule 48 and a two-part refilling boule 50 are shown.
The inside of the containment vessel outer circumferential boule 48 is divided into a plurality of small chambers whose upper and lower ends communicate with each other by a ring-shaped partition wall 61 and a radial partition wall 62.

That is, as shown in FIG. 6, the outer circumferential boule 48 of the containment vessel has an integral structure with its upper end connected to the lower end of the upper water replenishment boule 50.
Inside, as shown in FIGS. 6 and 7, a ring-shaped partition wall 61 and a radial partition wall 62 are arranged, respectively. As a result, the inside of the containment vessel outer circumferential boule 48 is divided into a plurality of small chambers whose upper and lower ends communicate with each other in the radial and circumferential directions.

Note that the other points have the same configuration as the first embodiment.

Next, the operation of this embodiment will be explained.

In the event of an accident, heat generated within the containment vessel 46 is transmitted to the containment vessel 46 wall and further to the containment vessel outer peripheral boule 48 . A natural circulation flow occurs within the containment vessel outer boule 48, with an upward flow on the inner circumferential side and a downward flow on the outer circumferential side. Then, boiling occurs on the inner wall of the containment vessel outer peripheral boule 48, and the containment vessel 46 is cooled by the latent heat of boiling.

By the way, if the heat generation within the containment vessel 46 is non-uniform, a natural circulating flow in the circumferential direction will occur within the containment vessel outer peripheral boule 48. However, in this embodiment, since the ring-shaped partition wall 61 and the radial partition wall 62 are provided in the containment vessel outer peripheral boule 48, the radial partition wall 62 in particular prevents the natural circulation flow in the circumferential direction. Vertical natural circulation flow and boiling are promoted. Therefore, the cooling efficiency of the containment vessel 46 can be improved.

FIG. 8 shows a third embodiment of the present invention, in which inner heat exchanger plate 71 and outer heat exchanger plate 72 are provided in the vertical direction.

That is, on the peripheral wall of the containment vessel 46, an inner heat transfer plate 71 is arranged vertically on the inner surface thereof, and an outer heat transfer plate 72 is arranged vertically on the outer surface.

Note that the other points have the same configuration as the first embodiment.

Next, the operation of this embodiment will be explained.

In the event of an accident, heat generated within the containment vessel 46 is transmitted to the walls of the containment vessel 46 via the inner heat transfer plate 71 on the inner circumferential wall of the containment vessel 46.
The heat is further transmitted to the water in the containment vessel outer peripheral boule 48 via the outer heat transfer plate 72 on the outer peripheral wall of the containment vessel 46 . In the containment vessel outer circumferential pool 48, a natural circulating flow is generated in which the inner circumferential side is an upward flow and the outer circumferential side is a downward flow. Then, boiling occurs on the inner wall of the outer peripheral pool 48 of the containment vessel, and due to the latent heat of boiling, the containment vessel 4
6 is cooled.

At this time, since the inner heat transfer plate 71 is provided in the vertical direction, the natural circulation flow within the containment vessel 46 is not hindered, and the inner wall area of the containment vessel 46 is substantially increased to improve heat transfer efficiency. Can be done. Further, since the outer heat transfer plate 72 is also provided in the vertical direction, the heat within the containment vessel 46 can be efficiently released to the containment vessel outer peripheral pool 48. In addition, the vertical natural circulation flow generated within the containment vessel outer circumferential boule 48 is not obstructed by the outer heat exchanger plate 72, and the circumferential natural circulation flow is suppressed. Since there is no stagnation caused by the heat transfer plate 72, the containment vessel 46 can be cooled quickly and efficiently.

〔Effect of the invention〕

As explained above, according to the present invention, in the event of a loss of coolant accident, the containment vessel can be cooled quickly and stably over a long period of time without requiring power or operation by an operator. Furthermore, since a large amount of heat can be removed from the containment vessel, the containment vessel can be made smaller and the cost of the reactor building can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a reactor containment vessel showing a first embodiment of the present invention, FIG. 2 is an enlarged perspective view of the outer circumferential pool of the compartmentalized containment vessel in FIG. 1, and FIG. An explanatory diagram showing the temperature distribution and the amount of heat transfer. Fig. 4 (a) is a graph showing changes in well pressure. Fig. 4 (b) is a graph showing corresponding temperature changes in each part. Fig. 5 is a graph showing condensation heat. A graph showing the influence of air partial pressure on the transmissibility, FIG. 6 is the second embodiment of the present invention.
FIG. 1 is a diagram corresponding to the embodiment, FIG. 7 is a plan view of FIG. 6,
FIG. 8 is a diagram corresponding to FIG. 1 showing the third embodiment of the present invention, and FIG.
The figure shows a cross-sectional view of a conventional reactor containment vessel. Figures 10 and 11 are cross-sectional views of a conventional reactor containment vessel of natural heat dissipation type. Figure 12 shows the temperature inside the outer peripheral pool of a conventional containment vessel. FIG. 3 is a diagram equivalent to FIG. 3 showing the distribution and the amount of heat transfer. 41...Reactor pressure vessel, 43...Dry well,
44... Pressure suppression pool, 45... Wet well, 46... Containment vessel, 48... Containment vessel outer circumference pool, 49... Segmented containment vessel outer circumference pool, 55... Atmospheric vent pipe, 61 ...Ring-shaped partition wall, 62...Radial partition wall, 71...Inner heat exchanger plate, 72...Outer heat exchanger plate.

Claims (1)

[Claims] 1. A containment vessel outer circumference pool is provided at the outer circumference of the containment vessel that stores the reactor pressure vessel, and a natural cooling system is provided to cool the containment vessel by increasing the temperature and evaporating water in the containment vessel outer circumference pool. A reactor containment vessel of a heat dissipation type, characterized in that the containment vessel outer peripheral pool is constituted by a plurality of small sectional containment vessel outer peripheral pools arranged in a height direction and a circumferential direction of the outer wall of the containment vessel. . 2. Natural heat dissipation type reactor containment in which a containment vessel outer peripheral pool is provided on the outer periphery of the containment vessel that stores the reactor pressure vessel, and the containment vessel is cooled by temperature rise and evaporation of water in this containment vessel outer peripheral pool. A nuclear reactor containment vessel, characterized in that the outer peripheral pool of the containment vessel is provided with a wall that divides the inside thereof into a plurality of small chambers in the radial and circumferential directions. 3. Natural heat dissipation type reactor containment, in which a containment vessel outer peripheral pool is provided on the outer periphery of the containment vessel that stores the reactor pressure vessel, and the containment vessel is cooled by temperature rise and evaporation of water in this containment vessel outer peripheral pool. A nuclear reactor containment vessel, characterized in that heat transfer plates are provided vertically on the inner and outer walls of the containment vessel facing the containment vessel outer peripheral pool.