JPH04313099A - Double-tank type atomic reactor - Google Patents

Abstract

PURPOSE:To absorb the difference in thermal expansions between a secondary container and a roof slab and to supress the increase in pressure at the time of sodium-water reaction accident. CONSTITUTION:A manometer seal 34 is provided between a secondary container 31 and a roof slab 33. The manometer seal 34 is composed of a double-cylinder flume 34a which is provided in the secondary container 32, a cylinder drum 34b which is provided at the roof slab 33 and a sealing liquid 34c which is injected into the double-cylinder flume 34a. The part between the double-cylinder flume 34a and the cylinder drum 34b is sealed with the sealing liquid 34a. Therefore, the difference in thermal expansions between the secondary container 31 and the roof slab 33 can be readily absorbed. The reaction product at the time of sodium-water reaction accident is discharged through the part between the double-cylinder flume 34a and the cylinder drum 34b, and the increase in pressure can be suppressed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-vessel tank-type nuclear reactor using liquid metal as a coolant, and more particularly to an improvement in the structure for absorbing thermal expansion differences.

0002

[Prior Art] FIG. 4 shows a conventional double tank nuclear reactor. In the figure, reference numeral 1 denotes a secondary vessel. This secondary vessel 1 is installed on a base slab 2 and has an upper end. The opening is closed by a roof slab 3. A telescopic shell 4 for absorbing thermal expansion of the secondary container 1 is provided at the connection portion between the secondary container 1 and the roof slab 3.

[0003] A pot-shaped primary container 5 whose upper end is reduced in diameter is arranged in the center of the interior of the secondary container 1.
is installed on the bottom mirror of the secondary container 1, and its upper end passes through the roof slab 3. The upper end opening of this primary container 5 is closed by a shielding plug 6 suspended from the roof slab 3.

[0004] A reactor core 7 is disposed at the center of the primary vessel 5 , and the reactor core 7 is installed at the bottom of the primary vessel 5 via a core inlet pressure plenum 8 . Also, core 7
At the upper end position, a primary system partition wall 11 is provided that divides the inside of the primary container 5 into an upper primary high temperature pool 9 and a lower primary low temperature pool 10.

A plurality of intermediate heat exchangers 12 and primary coolant electromagnetic pumps 13 are arranged at required intervals in the circumferential direction on the outer periphery of the core 7 in the primary vessel 5, penetrating the primary system partition wall 11. The upper end portions of these containers are suspended and supported by a stand 14 provided on the upper shoulder portion 5a of the pot-shaped primary container 5 via seal rings and bolts (not shown).

[0006] The intermediate heat exchanger 12 includes a primary high temperature pool 9.
Openings for primary coolant inflow and outflow are provided at corresponding positions in the primary low temperature pool 10, and the high temperature primary coolant in the primary high temperature pool 9 is supplied to the intermediate heat exchanger 12 from the upper opening. The coolant flows into the intermediate heat exchanger 12 and exchanges heat with a secondary coolant, which will be described later. The primary coolant after heat exchange is sent to the primary cold pool 10 from the lower opening.

Further, the primary coolant electromagnetic pump 13 has its suction port open into the primary low temperature pool 10, and
The discharge port is directly connected to the core inlet pressure plenum 8, and the primary coolant in the primary cold pool 10 sucked by the primary coolant electromagnetic pump 13 is transferred to the core inlet pressure plenum 8.
It is designed to be sent to the reactor core 7 via.

Bellows 15 are incorporated in the lower ends of the shells of the primary coolant electromagnetic pump 13 and the intermediate heat exchanger 12, respectively, to absorb thermal expansion. Further, a secondary coolant electromagnetic pump 16 is attached to the lower end of the intermediate heat exchanger 12, and the secondary coolant electromagnetic pump 16 is connected to the The next coolant is sucked and fed to the intermediate heat exchanger 12. Note that in this intermediate heat exchanger 12,
A secondary coolant flows inside a heat exchanger tube (not shown), and a primary coolant flows outside the heat exchanger tube.

On the other hand, inside the secondary container 1, a secondary system partition wall 18 is provided at the middle part in the vertical direction. Shoulder part 5
Upper secondary high temperature pool 19 having a liquid level above a
and a lower secondary cold pool 20. The secondary coolant that has undergone heat exchange within the intermediate heat exchanger 12 is discharged directly into the secondary high temperature pool 19 from the upper end of the intermediate heat exchanger 12.

Further, inside the secondary container 1, a plurality of steam generators 21 are arranged at required intervals in the circumferential direction, penetrating the secondary system partition wall 18, and each of these steam generators 21
is supported by hanging from the roof slab 3. At the position corresponding to each pool 19, 20 of this steam generator 21,
Each opening is provided with a secondary high temperature pool 19.
The high-temperature secondary coolant inside flows into the steam generator 21 from the opening at the top, where it is heat exchanged with the water sent through the water supply pipe 22, and after the heat exchange. The secondary coolant is delivered to the secondary cold pool 20 from the opening at the bottom.

[0011] This secondary coolant flows outside a heat transfer tube (not shown) disposed in the steam generator 21, and water from the water supply pipe 22 flows inside the heat transfer tube. It's flowing. Superheated steam generated by heat exchange within the steam generator 21 is sent to a steam turbine (not shown) via a superheated steam pipe 23 provided at the top of the steam generator 21 together with a water supply pipe 22. .

In FIG. 4, reference numeral 24 indicates a control rod drive mechanism provided in the shielding plug 6, and reference numeral 25 indicates a telescopic cylinder for absorbing thermal expansion provided at the upper end of the primary container 5.
Reference numeral 6 denotes a bellows for absorbing thermal expansion, which is provided at an intermediate portion between the intermediate heat exchanger 12 and the steam generator 21.

[0013]

[Problems to be Solved by the Invention] In the conventional double tank type nuclear reactor, an expandable shell 4 is provided in order to absorb the thermal expansion of the secondary vessel 1.
In a nuclear reactor of 10,000 KWe class, the diameter of the secondary vessel 1 is 10 to 1
5m, and the height is about 20m, and the amount of thermal expansion required for absorption is over 100 mm in the axial direction from installation to operation.
It extends to several tens of mm in the radial direction. Then, there is a problem in that it is not necessarily easy to apply the conventional expandable shell 4 to the secondary container 1 having a large diameter so as to absorb a large amount of thermal expansion.

The present invention has been made in consideration of these points, and can easily absorb the difference in thermal expansion between the secondary container and the roof slab, thereby reducing the pressure increase contained in the secondary container. The purpose is to provide a double tank type nuclear reactor that can improve the reliability of the reactor core against various factors.

[0015]

[Means for Solving the Problems] As a means for achieving the above object, the present invention provides a secondary vessel installed on a base slab and accommodating a steam generator, and a reactor core disposed inside the secondary vessel. A primary container for storing the secondary container, a roof slab installed on a base slab, and a manometer seal formed between the roof slab and an upper end opening of the secondary container, and the manometer seal includes a primary container for storing the secondary container. a groove-shaped double cylindrical gutter that is formed around the upper end opening of the container and opens upward; a cylindrical body that hangs down from the roof slab and whose lower end is inserted into the double cylindrical gutter; and the double cylindrical gutter. A liquid such as molten metal is injected into the container.

[0016] In the present invention, the base slab is provided with a pressure regulating mechanism that suppresses the pressure rise within the base slab by discharging to the outside the product of a sodium-water reaction accident in the steam generator. is preferred.

[0017]

[Operation] In the double tank nuclear reactor according to the present invention,
A manometer seal is formed between the roof slab and the upper end opening of the secondary container, and the space between the double cylindrical gutter on the secondary container side and the cylindrical body on the roof slab side is injected into the double cylindrical gutter. Sealed by liquid. Therefore, the relative displacement between the double cylindrical gutter and the cylindrical body is free, and it becomes possible to absorb a large amount of thermal expansion.

[0018] In addition, in the event of a sodium-water reaction accident in a steam generator, the pressure increase due to the products of the reaction is
Although it is necessary to suppress the pressure as soon as possible, the manometer seal makes it possible to easily and reliably release the pressure by discharging the liquid in the double cylindrical trough due to the pressure difference.

Further, in the present invention, by providing a pressure regulating mechanism in the base slab and discharging the reaction products to the outside, the increase in pressure within the base slab is also suppressed, thereby further improving reliability. becomes possible.

[0020]

Embodiment A first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows an example of a double tank nuclear reactor according to the present invention. In the figure, reference numeral 31 is a secondary vessel, and this secondary vessel 31 is installed on a base slab 32. A roof slab 33 is installed at the upper end opening of the base slab 32. A manometer seal 34 is formed between the upper end opening of the secondary container 31 and the roof slab 33.

[0022] This manometer seal 34
1. A double cylindrical gutter 34a in the form of a groove that opens upward and is provided on the outer peripheral edge of the upper end opening of the roof slab 33, and a cylindrical body 34b that hangs down from the roof slab 33 and has a lower end inserted into the double cylindrical gutter 34a.
and a sealing liquid 34c injected into the double cylindrical gutter 34a.
The sealing liquid 34c is made of molten metal such as solder or mercury, and the lower end of the cylindrical body 34b is submerged, and the sealing liquid 34c is formed between a non-contact double cylindrical gutter 34a and a cylindrical body. 34b.

The manometer seal 34 having such a configuration has the radial position of the cylindrical body 34b aligned with the double cylindrical gutter 3 in order to optimize its size in the operating state of the nuclear reactor.
4a, and the cylindrical body 3
The depth of submergence of 4b into the sealing liquid 34c and the axial position are also arranged to reach the target point in the operating state.

At the center of the interior of the secondary container 31, a pot-shaped K primary container 35 whose upper end is reduced in diameter is arranged. It passes through the roof slab 33. The upper end opening of this primary container 35 is closed by a shielding plug 36 suspended from the roof slab 33.

A reactor core 37 is disposed in the center of the primary vessel 35 , and the reactor core 37 is installed at the bottom of the primary vessel 35 via a core inlet pressure plenum 38 . Further, at the upper end of the core 37, as shown in FIG. 1, a primary system partition wall 41 is provided that divides the inside of the primary vessel 35 into an upper primary high temperature pool 39 and a lower primary low temperature pool 40.

At the outer periphery of the core 37 in the primary vessel 35,
A plurality of intermediate heat exchangers 42 and primary coolant electromagnetic pumps 43 are arranged at required intervals in the circumferential direction so as to penetrate through the primary partition wall 41, and their upper ends form a pot shape as shown in FIG. The primary container 35 is suspended and supported by a stand 44 provided on the upper shoulder 35a via a seal ring and bolts (not shown).

The intermediate heat exchanger 42 includes a primary high temperature pool 3.
9 and the primary low temperature pool 40 are provided with openings for inflow and outflow of the primary coolant, respectively, and the high temperature primary coolant in the primary high temperature pool 39 flows from the upper opening to the intermediate heat exchanger. The coolant flows into the intermediate heat exchanger 42 and undergoes heat exchange with a secondary coolant, which will be described later. The primary coolant after heat exchange is sent to the primary cold pool 40 from the lower opening.

The primary coolant electromagnetic pump 43 has its suction port open into the primary low temperature pool 40, and
The discharge port is directly connected to the core inlet pressure plenum 38,
The primary coolant in the primary cold pool 40 sucked by the primary coolant electromagnetic pump 43 is sent to the reactor core 37 via the core inlet pressure plenum 38 .

A bellows 45 is incorporated in the lower end of each body shell of the primary coolant electromagnetic pump 43 and the intermediate heat exchanger 42 so as to absorb thermal expansion. Further, a secondary coolant electromagnetic pump 46 is attached to the lower end of the intermediate heat exchanger 42 , and the secondary coolant electromagnetic pump 46 is connected to the secondary coolant through a through hole 47 provided at the bottom of the primary container 35 . The next coolant is sucked in and fed to the intermediate heat exchanger 42. In this intermediate heat exchanger 42, a secondary coolant flows inside heat exchanger tubes (not shown), and a primary coolant flows outside the heat exchanger tubes.

On the other hand, inside the secondary container 31, a secondary system partition wall 48 is provided at an intermediate portion in the vertical direction.
1 is divided by this secondary system partition wall 48 into an upper secondary high temperature pool 49 and a lower secondary low temperature pool 50 having a liquid level above the upper shoulder 35a of the primary container 35. . The secondary coolant that has undergone heat exchange within the intermediate heat exchanger 42 is discharged directly from the upper end of the intermediate heat exchanger 42 into the secondary high temperature pool 49.

Further, inside the secondary container 31, a plurality of steam generators 51 are arranged at required intervals in the circumferential direction, penetrating the secondary system partition wall 48, and each of these steam generators 5
1 is suspended and supported from the roof slab 33. Openings are provided in the steam generator 51 at positions corresponding to the pools 49 and 50, and the high temperature secondary coolant in the secondary high temperature pool 49 is supplied to the steam generator from the upper opening. 51 and undergoes heat exchange with water sent through the water supply pipe 52, and the secondary coolant after heat exchange is sent to the secondary low temperature pool 50 from the opening at the bottom. It is now possible to do so.

This secondary coolant flows outside a heat transfer tube (not shown) disposed in the steam generator 51, and water from the water supply pipe 52 flows inside the heat transfer tube. It's flowing. Superheated steam generated by heat exchange within the steam generator 51 is sent to a steam turbine (not shown) via a superheated steam pipe 53 provided at the top of the steam generator 51 together with a water supply pipe 52. .

A control rod drive mechanism 54 is attached to the shielding plug 36.
In addition, a telescopic shell 55 for absorbing thermal expansion is provided at the upper end of the primary vessel 35, and an expandable shell 55 for absorbing thermal expansion is provided at the intermediate portion of the intermediate heat exchanger 42 and the steam generator 51. A bellows 56 is provided for use.

By the way, the steam generator 5 in the secondary container 31
In 1, if a sodium-water reaction accident occurs,
Hydrogen gas, which is the main reaction product, increases the pressure in the internal space surrounded by the base slab 32 and the roof slab 33, so this must be avoided.

Therefore, in this embodiment, as shown in FIG.
A pressure regulating mechanism 59 consisting of a discharge system piping 57, a destruction plate 58 that is destroyed by a certain pressure, a cyclone separator (not shown), etc. is installed, for example, in the lining structure 60 of the base slab 32.
The hydrogen gas can be released to the atmosphere 61.

Next, the operation of this embodiment will be explained.

The primary coolant superheated in the core 37 flows into the intermediate heat exchanger 42 via the primary high temperature pool 39, exchanges heat with the secondary coolant in the intermediate heat exchanger 42, and then flows into the primary low temperature pool. Sent to 40. The primary coolant in the primary cold pool 40 is sucked in by the primary coolant electromagnetic pump 43 and sent to the reactor core 37 via the core inlet pressure plenum 38 .

On the other hand, the secondary coolant superheated by heat exchange within the intermediate heat exchanger 42 is discharged from the upper end of the intermediate heat exchanger 42 to the secondary high temperature pool 49, and is further transferred to the steam generator 5.
1 and exchanges heat with water from the water supply pipe 52. Superheated steam generated by this heat exchange is sent to a steam turbine (not shown) via a superheated steam pipe 53, and the secondary coolant whose temperature has been lowered by the heat exchange is sent to a secondary low temperature pool 50. The secondary coolant in the secondary cold pool 50 is sucked by the secondary coolant electromagnetic pump 46 through the through hole 47 and sent to the intermediate heat exchanger 42 .

By the way, since the secondary vessel 31 is heated by the high temperature secondary coolant during operation of the nuclear reactor,
The average temperature is around 400 degrees Celsius, and at the time of an accident it can reach even higher temperatures of around 600 degrees Celsius. At that time, due to the temperature difference from the time of installation, the amount of thermal expansion in the axial direction of the secondary container 31 is 10
0 to 200 mm, and the amount of radial thermal expansion is 30 to 60 mm.

In the manometer seal 34, the cylindrical body 3
4b has a relatively small temperature difference from the time of installation, and therefore, the displacement due to thermal expansion of the double cylindrical gutter 34a at the upper end of the secondary container 31 almost becomes a relative positional change with the cylindrical body 34b.

However, the amount of thermal expansion described above can be sufficiently absorbed by appropriately setting the dimensions of the double cylindrical gutter 34a.

[0042] Also, the secondary container 3 under normal operating conditions
The pressure of the inert gas (argon gas, etc.) in 1 is 100
~500mmAg, so for example, seal liquid 3
Assuming that the specific weight of 4c is about 10g/cm3,
Sealing performance can be ensured when the liquid level difference between the inner and outer surfaces is 10 to 50 mm.

On the other hand, a potential cause of pressure increase in the secondary container 31 is a sodium-water reaction caused by damage to the heat transfer tube of the steam generator 51 in the secondary container 31.

[0044] In this sodium-water reaction, so as not to impair the reliability of the primary vessel 35 and the reactor core 37,
It is important to relieve the pressure as quickly as possible, and the manometer seal 34 allows this to occur.

That is, the quasi-static equilibrium value due to the pressure increase in the secondary container 31 is
b is proportional to the depth of submersion into the sealing liquid 34c, for example, when the specific weight of the sealing liquid 34c is 10 g/cm
3, and assuming that the immersion depth of the cylindrical body 34b is 100 mm, the quasi-static equilibrium value is approximately 0.2 kg/cm2 g. Therefore, the diving depth should be set to 200-300
mm, and the inertial force of the sealing liquid 34c and the sodium
By configuring the flow path by appropriately utilizing the pressure loss depending on the flow path area etc. in the conduction path of hydrogen gas, which is a factor of pressure increase as a water reaction product, the quasi-steady state in the early stage of the sodium-water reaction can be maintained. The pressure increase value is 1.5 to 2K.
It can be suppressed to about g/cm2g.

[0046] As a result, the wall thickness of the primary container 35 of 50 mm, which has been set due to manufacturing reasons and other design controlling factors, can be reduced to 50 mm.
Even under such conditions, it becomes possible to prevent and suppress buckling of the primary vessel 35 due to an increase in pressure within the secondary vessel 31, and it becomes easy to ensure the reliability of the reactor core 37.

From inside the secondary container 31, the manometer seal 3
4 and reaches the inner space of the lining structure 60 of the base slab 32. After passing through the release system piping 57, the hydrogen gas reaches the pressure setting of the rupture plate 58 (for example, 0.5 Kg/cm2).
) When the pressure reaches the level above, the destruction plate 58 is destroyed and the pressure is released to the atmosphere 61.

[0048] In an actual system, when hydrogen gas is released to the atmosphere 61, it is combusted by an igniter or the like and released as water vapor.

[0049] By using the manometer seal 34, the difference in thermal expansion between the roof slab 33 and the secondary container 31 can be easily absorbed, and sufficient sealing performance can be obtained. Moreover, in the event of a sodium-water reaction accident, pressure rise can be reliably suppressed.

2 and 3 show a second embodiment of the present invention, in which a pressure regulation mechanism 69 is used in place of the pressure regulation mechanism 59 in the first embodiment.

That is, like the pressure regulating mechanism 59, this pressure regulating mechanism 69 is equipped with a discharge system piping 57, a rupture plate 58, and a cyclone separator (not shown), but the discharge system arrangement 57 has a lining structure. It hermetically passes through the object 60, and its tip is connected to the cylindrical body 34b of the manometer seal 34.

[0052] In other respects, the structure is the same as that of the previous embodiment, and the operation is also the same.

Thus, the pressure setting value of the rupture plate 58 of the pressure regulating mechanism 69 is changed to the opening target value of the manometer seal 34 (1.
5 to 2 Kg/cm2 g), and by appropriately setting the pressure loss of the discharge system piping 57 and the like until reaching the atmosphere opening 61, the opening function of the manometer seal 34 can be changed to the opening function of the rupture plate 58. It can be used as a backup for

That is, in this case, the reliability and buckling integrity of the primary container 35 can be ensured with redundancy by the opening function of the manometer seal 34, and moreover, in a relatively small scale sodium-water reaction, The manometer seal 34 does not open, thus preventing the sodium-water reaction product from flowing into the space between the secondary container 31 and the lining structure 60 located outside it, which helps in plant recovery after an accident. The process of restarting operations can be greatly simplified.

[0055]

[Effects of the Invention] As explained above, the present invention forms a manometer seal consisting of a double cylindrical gutter, a cylindrical body, and a sealing liquid between the roof slab and the upper opening of the secondary container. Therefore, thermal expansion between the roof slab and the secondary container can be easily absorbed and sufficient sealing performance can be obtained. Moreover, in the event of a sodium-water reaction accident, it is possible to prevent an excessive pressure rise, prevent and suppress buckling of the primary vessel, and improve the reliability of the reactor core.

[0056] In the present invention, by providing a pressure regulating mechanism in the base slab and discharging the products from the sodium-water reaction accident to the outside, the pressure increase in the base slab is suppressed and reliability is further improved. can be done.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a double tank nuclear reactor according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a double tank nuclear reactor according to a second embodiment of the present invention.

FIG. 3 is an enlarged view of part III in FIG. 2;

FIG. 4 is a sectional view showing a conventional double tank nuclear reactor.

[Explanation of symbols]

31 Secondary container 32 Base slab 33 Roof slab 34 Manometer seal 34a Double cylindrical gutter 34b Cylindrical body 34c Seal liquid 35 Primary container 37 Reactor core 51 Steam generator 59 Pressure regulating mechanism 69 Pressure regulation mechanism

Claims (2)

[Claims] Claim 1: A secondary vessel installed on a base slab and housing a steam generator; a primary vessel placed within the secondary vessel and housing a reactor core inside; and a roof slab installed on the base slab. , a manometer seal formed between the roof slab and the upper end opening of the secondary container, the manometer seal having a groove shape formed at the periphery of the upper end opening of the secondary container and opening upward. It has a double cylindrical gutter, a cylindrical body that is suspended from the roof slab and whose lower end is inserted into the double cylindrical gutter, and a liquid such as molten metal that is injected into the double cylindrical gutter. A double tank nuclear reactor characterized by: [Claim 2] A claim characterized in that the base slab is equipped with a pressure regulating mechanism that suppresses a pressure rise within the base slab by discharging products from a sodium-water reaction accident in the steam generator to the outside. The double tank nuclear reactor according to item 1.