JPS6350786A - Fast breeder reactor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a liquid total flexion sodium cooled fast breeder reactor, and particularly to a fast breeder reactor with a simplified system configuration.

(Prior Art) An example of a conventional fast breeder reactor of this type is shown in FIG. 3.

This is a so-called loop-type fast breeder reactor, in which the primary system including the reactor vessel 1 is connected to the steam system via the secondary system. and the steam system are not shown.

That is, the reactor vessel 1 contains therein a primary coolant 2 made of liquid metal sodium, and the reactor core 3 is placed in a state of being immersed in the primary coolant 2, and its upper end opening is opened by a plug 4. It's blocked.

The outlet nozzle 1a of the reactor vessel 1 is connected to the primary system inlet nozzle 6a of the intermediate heat exchanger 6 via the outlet pipe 5, while the inlet nozzle 1b of the reactor vessel 1 is connected to the primary system pump via the inlet pipe 7. It is connected to the discharge port 8a of No.8.

The primary system outlet nozzle 6b of the intermediate heat exchanger 6 is connected to the suction port 8b of the primary system pump 8 via a connecting pipe 9, and the connecting pipe 9, the outlet pipe 5, and the inlet pipe 7 constitute the primary system piping. , primary coolant 2 housed in the reactor vessel 1
is guided through this primary system piping and forcedly circulated into the reactor core 3.

Furthermore, the intermediate heat exchanger 6 and the primary system pump 8 installed in the primary system piping are considered as a pair, and multiple pairs are connected to the reactor vessel 1.
are arranged in a ring shape around the outer periphery of the

The secondary side (not shown) of the intermediate heat exchanger 6 is connected to a steam generator and a secondary pump in an annular manner via secondary system piping to form a secondary system. The intermediate heat exchanger 6 exchanges heat between the primary coolant 2 and the secondary coolant made of circulating liquid total flex sodium, and the secondary coolant is then transferred to the secondary coolant by a secondary system pump via a steam generator, etc. The steam generator is configured to circulate the steam and generate high-pressure steam using the steam generator.

As shown in FIG. 3, welded bellows 10 having a relatively large amount of expansion and contraction are interposed in the inlet piping 7 and the outlet piping 5, respectively, so that the inlet and outlet piping 7, through which the relatively high temperature primary cooling tube 2 flows, The thermal expansion displacement of 5 is absorbed by each welded bellows 10.

This makes it possible to reduce the amount of piping required for the inlet and outlet piping 7.5.

In a conventional fast breeder reactor configured in this way, in the unlikely event that water leaks in the secondary steam generator due to damage to a heat transfer tube, etc.
Even if a sodium reaction occurs, the influence of this reaction can be stopped in the secondary system, so that it can be prevented from spreading to the core 3 of the reactor vessel 1.

By the way, in response to the recent demands for downsizing fast breeder reactors and reducing the amount of material, it is possible to omit the secondary system mentioned above to meet the requirements, while configuring the heat transfer tubes of the steam generator to have a double tube structure. Therefore, it is conceivable to configure the system to prevent a water-sodium reaction accident from occurring due to leakage between the water supply/steam side and the secondary coolant side made of liquid metal sodium.

However, this method of omitting the secondary system prevents water-sodium reaction accidents from occurring in steam generators that are used under harsh conditions such as corrosion on the feed water and steam sides and high pressure. cannot be completely removed, and in the event of a water-sodium reaction accident, its influence will spread to the reactor core 3 of the reactor vessel 1.

Furthermore, the heat transfer tubes of the steam generator are huge, and configuring them all into a double tube structure poses a problem of high costs.

(Problems to be Solved by the Invention) As described above, when the secondary system of the conventional fast breeder reactor shown in FIG. In this case, it is not possible to completely eliminate water-sodium reaction occurrence accidents in the steam generator, and it is also impossible to prevent the effects of the reaction accidents from spreading to the reactor core, resulting in high costs.

Therefore, an object of the present invention is to prevent the effects of the reaction accident from spreading to the reactor core even if a water-sodium reaction accident occurs in the steam generator when the secondary system is omitted. The objective is to provide a fast breeder reactor that can

(Structure of the Invention) (Means for Solving the Problems) The present invention provides a steam generator that is interposed in the primary system piping to omit the conventional secondary system. In the event of a water-sodium reaction accident, the steam generator and primary pump are paired together with an isolation valve that separates them from the reactor vessel, and is constructed as follows.

Connecting the outlet nozzle and inlet nozzle of the reactor vessel, which houses the reactor core by immersing it in the primary coolant, through primary system piping,
A primary system pump that boosts the pressure of the primary coolant and a steam generator that generates steam by exchanging heat between the primary coolant and water supply are respectively installed in the primary system piping, and the primary system in the primary system piping is An isolation valve is provided in an inlet piping section that connects the discharge port of the pump and the inlet nozzle of the reactor vessel, and an outlet piping section that connects the primary system inlet nozzle of the steam generator and the outlet nozzle of the reactor vessel. Each was established.

(Function) The primary coolant in the reactor vessel is heated to a high temperature by the reactor core, and then is introduced into the interior from the primary system inlet nozzle of the steam generator through the outlet nozzle of the primary system piping. Ru.

In the steam generator, while the high-temperature primary coolant flows toward the primary system outlet nozzle, it exchanges heat with the feed water to generate steam, and the generated steam is supplied to the steam system etc. to do work.

The primary coolant that has exchanged heat with the water supply in the steam generator is sucked into the primary pump via the primary system piping, where it is pressurized, and then passes through the inlet piping section of the primary system piping and is returned to atoms from the outlet nozzle. The primary coolant is returned to the reactor vessel and heated again in the reactor core.

Thereafter, by repeating this process, steam is continuously generated in the steam generator, and the thermal efficiency of the steam generator can be improved compared to the conventional example having a secondary system.

In addition, since the secondary system is omitted, the system configuration is simplified,
The overall size and cost of the high-speed J-breeding furnace can be reduced.

Furthermore, in the unlikely event that a water-sodium reaction accident occurs in the steam generator/l' unit, by closing the isolation valve,
Since the steam generator and primary pump where the reaction accident occurred can be isolated from the reactor vessel, it is possible to prevent the effects of the water-sodium reaction accident in the steam generator from spreading to the core of the reactor vessel. can.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

FIG. 1 shows a vertical cross section of a main part of an embodiment of the present invention.
Reactor vessel 12 suspended in the installation pit on the installation floor 11
The outer periphery of is surrounded by an annular partition wall 13.

On the outer periphery of the annular partition wall 13, a plurality of pairs including a steam generator 14 and a primary pump 15 are arranged in an annular manner.

In FIG. 1, for convenience of explanation, a pair of steam generators 14 and a primary system pump 15 are arranged facing each other on the left and right sides of the reactor vessel 12, but as shown in FIG. It is arranged adjacent to the primary system pump 15 in the circumferential direction.

As shown in FIG. 1, the reactor vessel 12 is a cylindrical body with a bottom, and a primary coolant 16 made of liquid metal sodium is housed inside the reactor vessel 12.
is provided in an immersed state, and its upper end opening is sealed with a plug 18.

The reactor vessel 12 communicates with an outlet nozzle 12a for guiding the high-temperature primary coolant 16 heated in the reactor core 17 to the outside in the direction shown by the arrow in the figure, and a lower blenum below the reactor core 17. Reactor vessel-like piping 1 for introducing the primary coolant 16 into the lower blenheim of the reactor core 17 in the direction shown by the arrow in the figure
9 and an inlet nozzle 12b connected to the inlet nozzle 12b.

The outlet nozzle 12a of the reactor vessel 12 is connected to one end of the outlet pipe 20, and the other end extends laterally through the annular partition 13, and is connected to a primary system inlet nozzle located on the upper side of the body 14a of the steam generator 14. 14b.

The steam generator 14 has its inlet nozzle 14a connected to the reactor vessel 1.
It is suspended from the installation floor 11 so as to open at approximately the same height as the outlet nozzle 12a of No. 2, and for example, a large number of heat transfer tubes (not shown) through which the primary coolant 16 flows are housed in the body portion 14a. has been done.

These heat exchanger tubes are tied into a bundle, and the primary system nozzle 1
4b and a primary system outlet nozzle 14G at the bottom of the body 14a are communicated with each other.

On the other hand, the water supply section in the interior space of the body 14a of the steam generator 14 is connected to a water supply source (not shown), and the steam generation section (not shown) is connected to a steam system, and the high pressure steam generated in the steam generator 14 is connected to a steam turbine. The work is done in a steam system with etc.

In other words, the ? 3-temperature primary coolant 1
6 is directed toward the primary system outlet nozzle 14G and flows down through a large number of heat transfer tubes, heating the water supplied into the body 14a, and generating water in a steam generating section (not shown) in the body 14a. It is designed to generate steam. Note that the steam generator 14 may be configured such that supply water is passed through a heat transfer tube and a primary coolant is passed through a gap between the inner wall of the body portion 14a and the outer wall of the heat transfer tube.

The primary system outlet nozzle 14G of the steam generator 14 is connected to the connecting pipe 2.
1, the suction port 15 at the bottom of the primary system pump 15
connected to a.

The primary system pump 15 is suspended from the installation floor 1 so that the discharge port 15b on the upper side surface opens at approximately the same height as the inlet nozzle 12b of the reactor vessel 12, and both nozzles 15b, 12b They are connected by an inlet pipe 22.

The inlet pipe 22, the outlet pipe 20, and the communication pipe 21 constitute a primary system piping, and the primary coolant 16 in the reactor vessel 11 is forcedly circulated to the steam generator 14 via the primary system piping. There is.

In addition, welded bellows 23.23 with a large expandable base and isolation valves 24.24 are interposed in the middle of the outlet and inlet piping 20.22, respectively, and these 23, 23, 24, 24 are connected to the annular partition wall 13. 1% due to workers approaching through the vertical hole 13a.
Be able to carry out maintenance, inspection, and other work.

Each welded bellows 21.21 is a bellows joint with high expansion and contraction, for example, a plurality of ring plates cut into a ring shape are arranged in parallel along the axial direction, and the outer peripheral edge of the opposing surface of the adjacent ring plates is The welded parts are welded together or the inner peripheral edges are welded in a ring shape, and the welded parts between the outer peripheral edges and the inner peripheral edges are arranged alternately in the axial direction, and the welded parts between the outer peripheral edges are formed into bellows threads. In addition, the welded portions between the inner peripheral edges are formed in the bellows valleys.

Therefore, in the welded bellows 21, the pitch of the bellows peaks can be made shorter than the height of the bellows peaks, and the number of pitches per unit length can be increased, so that expansion and contraction ω can be significantly increased.

Next, the operation of this embodiment will be described.

When the fast breeder reactor operates, the primary coolant 16 in the reactor vessel 12 is heated to a high temperature by the reactor core 17 .

This high temperature primary coolant 16 is transferred to the outlet pipe 20 of the primary system pipe.
It is introduced into the interior of the steam generator 14 through the outlet nozzle 12a of the reactor vessel 12 through the primary system inlet nozzle 14b, and inside the body 14a, the primary system flows through a large number of heat transfer tubes (not shown). It flows down toward the outlet nozzle 14C.

During this time, the water supplied to the gap between the inner wall of the body 14a of the steam generator 14 and the outer wall of the heat exchanger tube is heat exchanged with the high temperature primary coolant 16 flowing inside the heat exchanger tube. Steam is generated in a steam generating section that is not equipped with a steam generator. The generated steam is supplied to a steam system via a steam pipe (not shown), and the steam system performs work such as driving a steam turbine, for example.

In this way, the steam generator 14 directly heats the feed water using the high-temperature primary coolant 16, resulting in improved thermal efficiency compared to conventional systems that indirectly heat the feed water via the secondary coolant. You can improve your performance.

Moreover, since the conventional secondary system is omitted, the system configuration can be simplified, and the entire fast breeder reactor can be downsized and cost reduced.

The primary coolant 16 that has undergone heat exchange with the water supply in the steam generator 14 passes from the primary system outlet 14C of the steam generator 14 through the communication pipe 21, and from the suction port 15a to the primary system outlet 14C.
After being sucked into 4C and boosted in pressure there, the discharge port 15
It is then introduced into the reactor vessel 12 through the inlet nozzle 12b through the inlet piping 22, and is then introduced into the lower blenheim below the reactor core 17 through the reactor vessel piping 19, where it is heated again by the reactor core 17. be done.

Thereafter, by repeating this process, steam is continuously generated in the steam generator 14.

Here, in the unlikely event that the steam side of the steam generator 14 malfunctions, the water
In the event of a sodium reaction accident, both isolation valves 24.24 of the outlet and inlet pipes 20.22 are closed.

As a result, the steam generator 14 and the primary system pump 15, where the water-sodium reaction accident occurred, are isolated from the reactor vessel 12 as a pair, so that the influence of the water-sodium reaction accident that occurred in the steam generator 14 is reduced. It is possible to prevent this from spreading to the reactor vessel 12.

In addition, restoration work can be performed while the steam generator 14 and the primary pump 15 are isolated as a pair by the isolation valves 24, 24, so that the work efficiency can be improved.

Furthermore, in this embodiment, highly expandable welded bellows 23, 23 are interposed in the middle of the outlet and inlet piping 20, 22 through which the relatively high temperature primary coolant 16 flows. Thermal expansion displacement of the piping 20°22 can be absorbed by these welded bellows 23, 23, and accordingly,
The burden on piping can be reduced.

Moreover, the outlet pipe 20 is installed almost horizontally between the outlet nozzle 12a of the reactor vessel 12, which opens at almost the same height, and the primary system inlet nozzle 14b of the steam generator 14. Since the welded bellows 23 is mainly loaded with axial displacement and the lateral cylinder m is reduced, the soundness of the welded bellows 23 can be improved like general bellows joints that are susceptible to lateral loads.

Regarding this, the same effect can be obtained for the welded bellows 23 interposed in the inlet pipe 22 for the same reason.

〔Effect of the invention〕

As explained above, the present invention omits the conventional secondary system by installing a steam generator in the primary system piping, and at the same time, the primary system piping is equipped with a steam generator on both sides of the outlet and inlet nozzles of the reactor vessel. An isolation valve was installed in each.

Therefore, according to the present invention, since the secondary system can be omitted, the entire fast breeder reactor can be downsized and cost reduced.

Furthermore, in the event that a water-sodium reaction accident occurs in the steam generator, the steam generator in which the reaction accident occurred can be isolated from the reactor vessel by closing the isolation valve.

As a result, it is possible to prevent the effects of a water-sodium reaction accident occurring in the steam generator from spreading to the reactor vessel.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of a main part of an embodiment of a fast breeder reactor according to the present invention, Fig. 2 is a partially cutaway cross-sectional view of Fig. 1, and Fig. 3 is a longitudinal cross-sectional view of a main part of a conventional example. be. 12...Reactor vessel, 12a...Outlet nozzle, 12
b... Inlet nozzle, 14... Steam generator, 14a.
...Body part, 14b...Primary system inlet nozzle, 14c...
・Primary system outlet nozzle, 15...Primary system pump, 16・
...Primary coolant, 17. Core, 20. Outlet piping (outlet piping section), 21.. Connection piping (part of primary system piping), 22.. Inlet piping (inlet piping section). , 23...
Welded bellows, 24... isolation valve. Representative Patent Attorney Yudo Nori Chika Hirofumi Mimata / Figure 2 Figure 3 Figure

Claims (1)

[Claims] The outlet nozzle and inlet nozzle of the reactor vessel, which accommodates the reactor core by immersing it in the primary coolant, are connected by a primary system piping, and the primary system piping is connected to a primary system pump that boosts the pressure of the primary coolant, and a primary cooling system. an inlet piping section that connects the discharge port of the primary system pump in the primary system piping and the inlet nozzle of the reactor vessel, each of which is provided with a steam generator that generates steam by exchanging heat between the material and the feed water; A fast breeder reactor, characterized in that an isolation valve is provided in each of the outlet piping sections connecting the primary system inlet nozzle of the steam generator and the outlet nozzle of the reactor vessel.