JPH02190796A - Cooling device for liquid metal cooling type nuclear reactor - Google Patents

Abstract

PURPOSE:To simplify the structure without forming an inner cylinder in double tube structure, etc., by forming a heat insulation space between an electromagnetic pump casing which has an opening in a main body barrel lower part and an electromagnetic pump at the upper part, and an internal cylinder having an opening at the lower part of the main body barrel. CONSTITUTION:High-temperature liquid metal while flowing a heat exchanger 29 where a helical heat conduction tube 30 is arranged supplied heat to feed water and falls in temperature itself to become low temperature liquid metal. This low- temperature liquid metal moves up in the electromagnetic pump casing 26 arranged having an opening at the lower part in a vapor producer 29, and the metal is applied with discharge pressure by the electromagnetic pump 40 and then returned to an intermediate heat exchange 15 through liquid metal exit piping 24 and cold leg piping. In the vapor producer 19, the heat insulating layer 45 is formed between the casing 26 having an opening here and the internal cylinder 29 with a free liquid surface FL2 and a seal ring fitted in contact with a flange for electromagnetic pump fitting installed above the vapor producer 19 to enable heat exchange between the high- temperature metal flowing down outside the internal cylinder 28 and the low- temperature metal moving up in the casing 26.

Description

Detailed Description of the Invention (Objective of the Invention) (Industrial Field of Application) The present invention relates to a cooling device for a liquid metal cooled nuclear reactor that uses liquid metal as a coolant, and particularly relates to a cooling system for a secondary system of a nuclear reactor. I want to improve! 11j.

(Prior art) In fast breeder reactors that use liquid metals such as sodium as cold fJ]44, the reactor coolant, that is, the secondary coolant, has a high level of radioactivity, so the secondary cooling system requires steam generation. isolated from the system.

On the other hand, heat exchange equipment between liquid metal and water is essential to generate the steam that drives the turbine generator.

The primary coolant, such as sodium, tends to react violently with air and water, and the heat of chemical reaction is large.

Therefore, in order to prevent the effects of the water-liquid metal chemical reaction from spreading to the reactor core when the steam side piping of the steam generator is damaged, a secondary cooling system is added between the primary cooling system and the steam generation system. is located.

A cooling system in a conventional liquid metal cooled nuclear reactor will be explained with reference to FIG.

At the center of the reactor vessel 1 is a reactor core 2 loaded with fuel assemblies.
A coolant 3 such as a liquid metal such as sodium is loaded to cool the core 2 . The coolant 3 is circulated by a primary main circulation bomb 4 installed inside the reactor vessel 1 . A primary cooling system is composed of a primary coolant 3 that cools the core, a main circulation pump 4, and an intermediate heat exchanger 5 that exchanges heat between the secondary coolant and the secondary coolant.

On the other hand, the secondary cooling system includes an intermediate heat exchanger 5, a steam generator B6 that generates steam to be supplied to a turbine generator (not shown), and a vertical secondary main circulation pump 7 for circulating the secondary coolant.
and first to third piping 8a, 8 connecting these devices.
b, 8c.

In the conventional secondary cooling system, the steam generator 6 and the secondary main circulation pump 7 are placed in separate buildings with the reactor building 9 as a boundary.

As mentioned above, according to the conventional arrangement of the secondary cooling system,
A secondary main circulation pump 7 and a steam generator 6 are installed separately,
These equipment and piping occupied a large proportion of the space in the reactor auxiliary building, making it uneconomical to increase the size of the building and ancillary equipment such as drain tanks.

In addition, since the connection parts of the pipes 8a, 8b, and 8c that connect the steam generator 6 and the secondary main circulation pump 7, etc. are all fixed anchor points, the pipes connecting each II weapon absorb thermal expansion. do. Therefore, it is necessary to form a pipe loop or meander in the middle of the pipe, which has the disadvantage that the length of the pipe becomes long, the space occupied by the pipe becomes large, and the size of the incidental equipment increases.

Therefore, a cooling system for a liquid metal-cooled nuclear reactor that can simplify the equipment structure and arrangement to shorten piping length, reduce the space volume of the reactor building and reactor auxiliary building, and reduce plant construction costs. As JP-A-63
There is one disclosed in Japanese Patent No. -58290.

That is, as shown in FIG. 9, in this cooling II, an intermediate heat exchanger 5 disposed inside the reactor vessel 1 and a steam generator 6 disposed outside the reactor vessel 1 are connected via piping, and steam is then A liquid metal inlet pipe 6b is provided at the upper part of the main body shell 6a of the generator 6, and a liquid metal riser pipe 6C having an opening at the lower part of the main body 1146a is provided in the axial direction of the main body shell 60. A liquid metal outlet pipe 6d is connected thereto, and an electromagnetic pump 6f is further arranged in a space 6e above the liquid metal level around the upper part of the liquid metal riser pipe 6C.

(Problem to be Solved by the Invention) However, in the cooling device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 63-58290, a heat transfer tube shroud having a heat insulating structure on the outside of the liquid metal riser pipe in the steam generator is This heat exchanger tube shroud has a double pipe structure and has an insulated space inside.The outside of the heat exchanger tube shroud is high temperature and the inside is cold, so a structure that absorbs thermal expansion is required. As a result, there is a problem that the structure becomes larger and more complicated.

In addition, in the above conventional example, the electromagnetic pump has a structure that allows it to be handled, and a gap is formed between the liquid metal riser pipe and the electromagnetic pump casing. A surface will be formed. the result,
Since there is no pressure loss when the plant is shut down, liquid metal could rise to the electromagnetic pump flange installed at the top of the steam generator and leak. Even during normal operation, the gas in the gap may enter the liquid metal, causing the liquid metal level to rise and leaking from the top of the steam generator, resulting in a problem that reduces the reliability of the device. There is.

The present invention has been made in consideration of the above circumstances, and is a heat exchanger tube shroud (inner tube) having a double tube structure and a thermal expansion absorption structure.
To provide a cooling device for a liquid metal cooled nuclear reactor that can be insulated without using a liquid metal, maintains the liquid metal level at the lower part of the steam generator, and prevents the liquid metal from leaking from the upper part of the steam generator. With the goal.

[Structure of the invention]

(Means for Solving the Problems) A cooling device for a liquid metal cooled nuclear reactor according to the present invention connects an intermediate heat exchanger disposed inside a reactor vessel and a steam generator disposed outside the reactor vessel through piping. A cooling device for a liquid metal cooled nuclear reactor that is connected to the main body of the steam generator includes a liquid metal inlet pipe provided at the top of the main body of the steam generator, and an opening provided in the axial direction of the main body of the main body and an opening at the bottom of the main body. and an electromagnetic pump casing for lifting liquid metal having an electromagnetic pump on the upper part, a liquid metal outlet pipe connected to the upper end of the casing, and an outer side of the electromagnetic pump casing provided along the axial direction and having an upper end connected to the upper part of the main body body. The electromagnetic pump casing is characterized by comprising an inner cylinder connected to the main body barrel and having an opening at the lower part of the main body, and a space is formed between the electromagnetic pump casing and the inner cylinder.

(Function) In the present invention having the above configuration, the liquid metal heated by the intermediate heat exchanger passes through the liquid metal inlet pipe,
The water is supplied to the steam generator and moves down the steam generator, exchanging heat with the feed water and generating steam. The liquid metal whose temperature has been lowered through heat exchange is sucked up from the lower end opening of the electromagnetic pump casing by the action of the electromagnetic pump, and roughly sent back to the intermediate heat exchanger. An electromagnetic pump disposed in a space above the liquid metal level around the upper part of the electromagnetic pump casing creates a magnetic field that moves the liquid metal in the direction of the liquid metal outlet piping.

In addition, the liquid metal heated by the intermediate heat exchanger and cooled by heat exchange between the liquid metal supplied to the steam generator and the water side is insulated by the space formed between the inner cylinder and the electromagnetic pump casing, and further The pressure in this space maintains the entire liquid level at the bottom of the steam generator and prevents liquid metal from leaking from the top of the steam generator.

(Example) The present invention will be described below based on illustrated embodiments.

FIG. 1 is a system diagram showing an embodiment of a cooling device for a liquid metal cooled nuclear reactor according to the present invention. In the same figure, the symbol @1
0 indicates a reactor vessel of a liquid metal cooled nuclear reactor, and a reactor core 11 is disposed within this reactor vessel 10. The reactor core 11 is cooled by primary cooling 013 of the reactor-subcooling system 12. The reactor secondary cooling system 12 has a primary main circulation bomb 14 and an intermediate heat exchanger 15 disposed inside the reactor vessel 10, and the primary cooling system 12 supplies the primary coolant inside the reactor vessel 10 by means of the primary circulation bomb 14. 13 are circulated.

The primary coolant 13 of the reactor secondary cooling system 12 is heat exchanged with the secondary coolant 17 of the reactor secondary cooling system 16 in the intermediate heat exchanger 15 . This secondary cooling system 16 is arranged between the reactor-secondary cooling system 12 and the steam generation system 18. The reactor secondary cooling system 16 is installed in the reactor building to connect the intermediate heat exchanger 15 and the steam generator 19 disposed outside the reactor vessel 10, and the intermediate heat exchanger 15 and the steam generator 19. It is composed of hot leg piping 21 and cold leg piping 22 which are arranged through the wall 2o.

Liquid metal inlet and outlet pipes 24 and 25 are provided in the upper part of the main body shell 23 of the steam generator 19. On the other hand, inside the main body shell 23, an electromagnetic pump casing 26 having an n-port at the lower part is disposed along the central axis of the main body shell 23, and a liquid metal outlet pipe 24 is connected to the upper end of the electromagnetic pump casing 26.

Furthermore, an electromagnetic pump 40 is disposed above the electromagnetic pump casing 26.

By the way, the steam generator 19 has a vertical cross-sectional structure shown in FIG. An inner cylinder (heat exchanger tube shroud) 28 is arranged, and a large number of helical heat exchanger tubes 30 are further arranged in an annular space (heat exchange chamber 29) outside the inner cylinder. Further, a free liquid surface FL1 of the liquid metal is formed inside the upper part of the main body body 23, and a space 47 above the free liquid surface FL1 absorbs volume changes due to thermal expansion of the liquid metal. There is.

On the other hand, the water supply inlet section is constituted by the water inlet pipe 32 into which the water supplied from the water supply pump 31 in FIG. 1 flows, the water inlet header 33, the water inlet distribution pipe 34, and the water inlet water v35. Ru. In addition, the steam exit portion is an outlet steam chamber 36,
It is composed of an outlet steam distribution pipe 37, an outlet steam header 38, and an outlet steam piping 39.

FIG. 3 is a plan view of the steam generator N19 in FIG. 2, in which the liquid metal inlet pipe 25 is branched into two lines and
3, and a liquid metal outlet pipe 24 is led out from the center of the top of the main body.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, showing the top of the steam generator 19. An electromagnetic pump 40 is provided on the inner periphery of the enlarged diameter part of the upper part of the electromagnetic pump casing 26, and this electromagnetic pump 40 is a two-stator coil in which electromagnetic coils 42 are wound inside and outside of a liquid metal channel 41 formed in an annular shape. The system uses a current from an external power source to generate RAS and circulate the liquid metal.

Further, the electromagnetic pump casing 26 having the Wt magnetic water pump 40 has its upper flange connected to the flange of the liquid metal outlet pipe 24, and the liquid metal outlet pipe 24 is further connected to the cold leg pipe 22.

By the way, as shown in FIGS. 2 and 4, the inner cylinder 28 is
The main body barrel 23 has an opening in the lower part thereof, and is disposed outside the electromagnetic pump casing 26 along the axial direction. Further, an electromagnetic pump mounting flange 43 is formed at the upper end of the inner cylinder 28, and a seal ring 44 seals between this flange 43 and the upper flange of the electromagnetic pump casing 26. As a result, a space is formed between the electromagnetic pump casing 26 and the inner cylinder 28, and as a result, a heat insulating layer 45 is formed between the free liquid level FL2 between the electromagnetic pump casing 26 and the inner cylinder 28 and the seal ring 44. are doing. As shown in FIG. 5, this free liquid level FL2 is located at a position where the pressure of the heat insulating layer 45 and the pressure of the liquid metal are balanced.

Next, the operation of the above embodiment will be explained.

Heat is transferred to the secondary cooling system 16 via the intermediate heat exchanger 15 by circulating the primary coolant 13 that cools the heat generated in the reactor core 11 using the primary main circulation bomb 14 .

On the other hand, the liquid metal in the secondary cooling system 16 is circulated by the electromagnetic pump 40 built into the steam generator 19, and the high-temperature liquid metal heated in the intermediate heat exchanger 15 passes through the hot leg piping 21, and the liquid metal inlet piping 25 flows into the steam generator 19.

The Bm liquid metal then flows down inside the heat exchange chamber 29 in which the helical heat transfer tube 30 is arranged, applying heat to turn the feed water into steam, and the temperature of the Bm liquid metal decreases to become a low-temperature liquid metal. This low-temperature liquid metal rises inside the electromagnetic pump casing 26 which is open at the lower part of the steam generator 19, and is further applied with discharge pressure by the electromagnetic pump 40, and then flows through the liquid metal outlet piping 24 and the cold leg. It is refluxed to the intermediate heat exchanger 15 via the pipe 22.

In this way, the liquid metal forms the above-mentioned flow, and especially in the leakage generation 119, the free liquid level FL2 between the electromagnetic pump casing 26 and the inner cylinder 28, which is open at the lower part, A seal ring 44 that is in close contact with an electromagnetic pump mounting flange 43 installed on the top of the steam generator 19
A heat insulating layer 45 is formed between the t% temperature liquid metal flowing down the outside of the inner cylinder 28 and the 1fla pump casing 2.
This prevents heat exchange with the low-temperature liquid metal rising inside the tube.

Note that the free liquid level FL2 is at a pressure equilibrium position between the heat insulating layer 45 and the liquid metal at the bottom of the steam generator 19, and therefore, when filling the liquid metal, the pressure of the heat insulating layer 45 is adjusted to the free liquid level FL2.
is set so that it is at the bottom of the steam generator 19. and,
When the plant is stopped, etc., the flow of liquid metal stops, so there is no loss of pressure, and the pressure rises at the bottom of the steam generator 19. However, the position where the pressure is balanced with the pressure of the heat insulating layer 45 is about the bottom of the steam generator 19. position, and the free liquid level F
L2 does not rise to the upper seal ring 44 of the steam generator 19, and there is no possibility of liquid leakage.

By the way, in the steam generator 19 shown in FIG.
On the water/steam side, the water fed from the water supply pump 31 (shown in the first diagram) flows into the water inlet header 33 from the water inlet piping 32, is divided in flow rate by the water inlet distribution piping 34, and is then divided into multiple streams. The water inlet reaches the water chamber 35. This water inlet water chamber 35
The feed water distributed into the inside of the helical coil heat transfer tube 30 rises inside the helical coil heat transfer tube 30 and exchanges heat with the liquid metal, reaches a temperature of 1 and becomes steam, and then reaches the outlet steam 'J36. After passing through the outlet steam distribution pipe 37 and merging at the outlet steam header 38, the steam flows out from the outlet steam pipe 39 and is sent to a steam turbine (not shown).

As described above, according to this embodiment, the inner cylinder 28 can be insulated without having a double pipe structure, so the structure is simplified and the manufacturability of the steam generator 19 is improved.

In addition, since the free liquid level FL2 between the electromagnetic pump casing 26 and the inner cylinder 28 can be stably maintained during normal operation or when the plant is stopped, the heat insulation function of the heat insulation F145 is not impaired, and the liquid metal is vaporized. There is no leakage from the upper part of the generator 19.

Furthermore, according to this embodiment, by incorporating the electromagnetic pump 40 into the steam generator 19 and integrating it with the casing 26, it is possible to eliminate the secondary main circulation pump.
It is possible to significantly shorten the piping length.

6 and 7 each show a steam generator according to another embodiment of the present invention, and the same members as those in the previous embodiment are given the same reference numerals. In the example, the electromagnetic pump casing 26 is inside! It is formed shorter than 9128. Incidentally, below the steam generator 19, there is almost no temperature difference between the liquid metal flowing down the inner cylinder 28 and the liquid metal flowing upward inside the electromagnetic pump casing 26, so no insulation is required. Therefore, the lower length of the electromagnetic pump casing 26 is set so that the free liquid level FL2 of the liquid metal is maintained stably during normal operation, when the plant is stopped, etc., and the insulation effect is maintained. According to this embodiment, the structure is further simplified and the manufacturability is improved compared to the previous embodiment, and the maintainability of the electromagnetic pump 40 is also improved. The rest of the structure and operation are the same as those of the previous embodiment, so the explanation thereof will be omitted.

Furthermore, in the embodiment shown in FIG. 7, the electromagnetic pump casing 26 is made significantly shorter than the inner cylinder 28, and the space between the electromagnetic pump casing 26 and the upper part of the inner cylinder 28 is insulated) fJ4
5a. A free liquid level FL3 is formed at a position where the pressure of the thermal layer 45a and the pressure of the liquid metal are in equilibrium. Further, at the lower end of the electromagnetic pump casing 26 in the axial direction, a liquid metal riser pipe 46 is arranged at a predetermined interval J3, and the lower end of the liquid metal riser pipe 46 extends to the lower end of the inner station 28 and is opened. There is. And liquid metal upper boundary tube 4
The upper end of 6 is bent and fixed to the inner cylinder 28 in a liquid-tight manner.

Therefore, a heat insulating layer 45b is formed in the space between the liquid metal riser pipe 46 and the inner cylinder 28, and the free liquid level FL2 is at a position where the pressure of this heat insulating layer 45b and the pressure of the liquid metal are equal to 11ti-v.
is formed. According to this embodiment, the maintainability of the electromagnetic pump 40 can be improved without significantly increasing the heat insulation effect. The structure and operation of this unit are the same as those of the previous embodiment, so the explanation thereof will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, since a space is formed between the electromagnetic pump casing whose lower end is open and the inner cylinder, this space becomes a heat insulating layer, and the inner cylinder has a double pipe structure, a bellows structure, etc. This makes it possible to simplify the structure and improve manufacturability.

In addition, the free liquid level can be maintained stably in the space between the electromagnetic pump casing and the inner cylinder, which prevents liquid metal from leaking from the top of the steam generator, greatly improving reliability. play.

[Brief explanation of the drawing]

Figure 1 shows a cold 741 of a liquid metal cooled nuclear reactor according to the present invention.
FIG. 2 is a half-IUI plan view showing the structure of the steam generator in FIG. 1, FIG. 3 is a plan view of the steam generator in FIG. 2, and FIG. 4 is a system diagram showing an example of equipment. 3 is a sectional view taken along line IV-■, FIG. 5 is an enlarged vertical sectional view showing lI43i at the bottom of the steam generator in FIG. 2, and FIGS. A half-assembly sectional view showing the structure of a steam generator in another embodiment, and FIGS. 8 and 9 are system diagrams showing a cooling device for a conventional liquid metal cooled nuclear reactor. DESCRIPTION OF SYMBOLS 10... Reactor vessel, 11... Reactor core, 15... Intermediate heat exchanger, 19... Steam generator, 23... Main body shell, 24... Liquid metal outlet piping, 25...・Liquid metal inlet piping, 26...electromagnetic pump casing, 28...
Inner cylinder, 29... Heat exchanger, 40... Electromagnetic pump, 4
3...7 langes for electromagnetic pump installation, 44...Seal ring, 45...Insulating layer, 46...Liquid metal riser pipe, FLI, FL2°F1a...Free liquid level. Applicant's agent Hisashi Hatano Figure E-=7-1--2-Co

Claims (1)

[Claims] In a cooling system for a liquid metal-cooled nuclear reactor, which has a pipe connection between an intermediate heat exchanger disposed inside the reactor vessel and a steam generator disposed outside the reactor vessel, the main body shell of the steam generator is A liquid metal inlet pipe provided at the upper part, an electromagnetic pump casing for raising the liquid metal, which is provided in the axial direction of the main body shell, has an opening at the lower part of the main body shell, and has an electromagnetic pump at the upper part, and is connected to the upper end of this casing. an inner cylinder provided along the axial direction on the outside of the electromagnetic pump casing and having an upper end connected to the upper part of the main body body and having an opening at the lower part of the main body body, the inner cylinder having an opening in the lower part of the main body body, A cooling device for a liquid metal cooled nuclear reactor, characterized in that a space is formed between the inner cylinder and the inner cylinder.