JPS6244694A - Nuclear reactor - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to nuclear reactors that use liquid metal as a coolant, such as sodium-cooled fast breeder reactors.

[Technical Background of the Invention] In general, fast breeder reactors use liquid metals such as liquid sodium as coolants. −
A secondary coolant circulation pump circulates the primary coolant through the core and an intermediate heat exchanger, and this intermediate heat exchanger exchanges heat with the secondary coolant. The system is configured to circulate the steam to obtain high pressure steam. Fast breeder reactors with such a configuration can be roughly divided into two types: loop type and tank type.

First, the schematic configurations of these loop-type and tank-type fast breeder reactors will be explained.

FIG. 5 is a diagram showing a schematic configuration of a loop type fast breeder reactor, and reference numeral 101 in the figure indicates a reactor vessel. This reactor vessel 10
1 contains a coolant 102 and a reactor core 103. The reactor core 103 is composed of a plurality of fuel assemblies, control rods, etc. (not shown). Further, the reactor core 103 is supported by the reactor vessel 101 via a core support mechanism 104. Upper opening 101A of the reactor vessel 101
is closed by a roof slab 105.

A core upper mechanism 106 is installed above the reactor core 103 so as to penetrate through the roof slab 105 .

The coolant 102 flows upward through the reactor core 103, and its temperature increases due to the heat of nuclear reaction in the reactor core 103.

The heated coolant 102 flows out above the core 103 and is transferred to the circulation pump 112 via the coolant outflow pipe 111. Roughly pressurized by this circulation pump 112,
It is transferred to an intermediate heat exchanger 113. This intermediate heat exchanger 1
At 13, it is cooled by exchanging heat with the secondary coolant, and the coolant inflow pipe, 114f*l, 41-0, 8f1
10"1f7) is supplied to the lower part of the F core 103. The same cycle is repeated thereafter. In the figure, the reference numeral 115 indicates the reactor building, and the reference numeral 116 indicates the safety vessel.

Next, the configuration of the tank type fast breeder reactor will be explained with reference to FIG. The reference numeral 201 in the figure is a reactor vessel, and inside this reactor vessel 201 there is a coolant 202 and a reactor core 203.
is accommodated. This core 203 is composed of a plurality of fuel assemblies, control rods, etc. (not shown). This reactor core 203 is supported by the reactor vessel 201 via a core support mechanism 204. The inside of the reactor vessel 201 is divided into upper and lower halves by a partition wall 205, and an upper plenum 2
06, and the lower part is a lower plenum 207. An upper part mechanism 209 of the reactor vessel 201 is installed to penetrate the roof slab 208. An intermediate heat exchanger 211 and a circulation pump 212 are provided on the outer peripheral side of the core 203.
are alternately arranged at equal intervals in the circumferential direction. In addition, code 2 in the figure
13 is a reactor building, and 214 is a safety vessel.

According to the above configuration, the coolant 202 flows upward through the reactor core 203 and is heated by the nuclear reaction heat of the reactor core 203 at this time. The heated coolant 202 flows into the upper plenum 206 and further into the intermediate heat exchanger 211 . There, it is cooled by exchanging heat with the secondary coolant. The cooled coolant 202 flows into the lower plenum 207 and then into the circulation pump 212 . It is pressurized by this circulation pump 212 and is again supplied to the lower part of the reactor core 203 . The same cycle is repeated thereafter.

[Problems with background technology] According to the above configuration, there were the following problems.

In the case of a loop type fast breeder reactor, piping through which high-temperature coolant 101 flows is arranged in a complicated manner outside the reactor vessel 101.
There was a problem in that the fruiting device would be large and the reactor building that houses the entire reactor would also be large.

On the other hand, in the case of a tank-type fast breeder reactor, the intermediate heat exchanger 21
1 and the circulation pump 212 are housed inside the reactor vessel 201, there is no need for a complicated piping configuration for circulating the coolant 202 outside the reactor vessel 201. There was a problem that 201 became large.

Furthermore, due to the increase in the size of the reactor vessel 201, the reactor vessel 201 has to be divided into multiple pieces for transportation reasons, but these multiple pieces have to be assembled on site, which makes the work difficult. there were. Further, as described above, since the circulation pump 212 and the intermediate heat exchanger 211 are housed inside the reactor vessel 201, the reactor vessel 201
There was not enough space within the building, making maintenance and inspection work difficult.

As described above, conventional fast breeder reactors, both loop-type and tank-type, have the problem of becoming larger and more complex. This is due to the need for a secondary cooling system between the secondary cooling system and the steam system. Therefore, it has been considered to eliminate the onboard secondary cooling system and directly exchange heat between the secondary cooling system and the steam system. In the case of this method, in order to flow the activated sodium in the primary cooling system directly into the evaporator, activation of the water vapor system, diffusion of tritium, making the steam generator a controlled area, sodium chloride when the steam generator heat exchanger tube breaks, and There is a concern that the primary cooling system may be damaged due to pressure waves caused by the (Na)/water reaction.

[Object of the Invention] The present invention has been made based on the above points, and its purpose is to solve the various problems mentioned above, and to - adopt a method of directly exchanging heat between a water cooling system and a steam system. The object of the present invention is to provide a nuclear reactor that can effectively simplify and downsize the configuration.

[Summary of the Invention] That is, a nuclear reactor according to the present invention includes: a reactor vessel that accommodates a coolant and a reactor core; a circulation pump that is installed in the reactor vessel and pressurizes the coolant that has passed through the reactor core and has been heated; The coolant installed outside the reactor vessel and pressurized by the circulation pump is introduced through the coolant 1 outflow pipe and exchanges heat with the steam system to generate steam, and the coolant is cooled by heat exchange. an evaporator that returns water to the reactor vessel through a coolant inflow pipe, and a heat transfer tube that is disposed within the evaporator and has a double piping structure and allows feed water to flow into the inner heat transfer tube. This is a characteristic feature.

In other words, a circulation pump is installed inside the reactor vessel, and an evaporator is installed outside the reactor vessel, and the heated primary coolant is passed through the circulation pump to the evaporator without the intervention of conventional secondary coolant. The water is transferred to the water supply and exchanged heat directly with the water supply. This solves the problems of the conventional loop type and tank type, simplifies the overall configuration without increasing the size of the reactor vessel, and eliminates the disadvantages of the secondary coolant, which can be avoided by using the heat transfer tubes in the evaporator. The aim is to effectively solve this problem by creating a double piping structure.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is a sectional view showing a schematic configuration of a fast breeder reactor according to an actual roadside system, and FIG. 2 is a view taken along arrow I[-II in FIG. 1. In the figure, reference numeral 1 indicates a reactor building, and reference numeral 2 indicates a reactor vessel.

This reactor vessel 1 is supported by the reactor building 1 via a ring gutter 3. Further, a safety vessel 4 is installed on the outer peripheral side of the reactor vessel 2.

This safety vessel 4 is also supported by the reactor building 1.

A coolant 5 and a reactor core 6 are housed within the reactor vessel 2 . This core 6 is composed of a plurality of fuel assemblies, control rods, etc. (not shown). Further, the reactor core 6 is supported by the reactor vessel 2 via a core support mechanism 7. A partition wall 8 is installed between the reactor core support mechanism 7 and the reactor vessel 2, and the partition wall 8 divides the inside of the reactor vessel 2 into two vertically, with the upper part serving as an upper plenum 9 and the lower part serving as a lower plenum. It is set at 10. The upper opening 2A of the reactor vessel 2 is closed by a roof slab 11. The roof slab top 1 is composed of a fixed plug 12 fixed to the reactor vessel 2, and a rotary plug 13 rotatably mounted on the fixed plug 12. Above the core 5, a core upper mechanism 14 is provided with the rotary plug 13.
It is placed through the. The core upper mechanism 14 is provided with a control rod drive mechanism for driving the control rods. A cover gas space 21 is formed between the liquid surface 5A of the coolant 5 and the roof slab 11, and an inert gas such as argon gas is filled in this cover gas space 21.

On the outer peripheral side of the core 5, circulation pumps 22 are arranged at equal intervals in the circumferential direction, as also shown in FIG. Further, as shown in FIG. 2, a coolant inflow pipe 23 is disposed between the plurality of circulation pumps 22. The circulation pump 22
A coolant outflow pipe 25 is connected to the discharge side of the reactor vessel 1 , and this coolant outflow pipe 25 is connected to an evaporator 31 installed outside the reactor vessel 1 . A plurality of evaporators 31 (four in this embodiment) are installed. That is, the coolant 5 flows upward through the core 6,
The temperature rises due to the heat of nuclear reaction. This heated cold W material 5 flows into the upper plenum 9 above the core 6, and circulates through the circulation pump 2.
2. The high-temperature coolant 5 discharged from the circulation pump 22 is transferred to the plurality of evaporators 31 via the coolant outflow pipes 25, respectively. and evaporator 31
The coolant is cooled by exchanging heat with the flowing removed water, and is supplied to the lower part of the reactor core 5 via the coolant inflow pipe 23. On the other hand, water is heated and turned into steam, which is transferred to a turbine system (not shown) and used for power generation. Repeat the same sakshi below.

Next, the configuration of the evaporator 31 will be explained with reference to FIGS. 3 and 4. The heat transfer tube 41 of the evaporator 31 of this embodiment has a double piping structure. That is, as shown in FIGS. 3 and 4, the heat exchanger tube 41 is connected to the inner heat exchanger tube 4.
2 and an outer heat exchanger tube 43, and the water supply flows through the inner heat exchanger tube 42. This reliably prevents radioactive contamination of the water supply by the secondary coolant 2. Moreover, between the inner heat exchanger tube 42 and the outer heat exchanger tube 43, there is an annulus air M4.
It is 4. In the figure, reference numeral 45 indicates an inner heat exchanger tube plate, and reference numeral 46 indicates an outer heat exchanger tube plate.

i According to the above configuration, the primary coolant 2 flows into the evaporator 31 through the secondary coolant inlet 51, is cooled by exchanging heat with water, and flows out through the primary coolant outlet 52. On the other hand, water flows into the inner heat exchanger tube 42 through the water supply inlet 61, and when flowing through the inner heat exchanger tube 42, it exchanges heat with the primary coolant 2 flowing outside the outer heat exchanger tube 43. It heats up and becomes steam, which flows out through the steam outlet 62.

According to this embodiment, the following effects can be achieved.

(1) First, in the overall configuration of the reactor, unlike the conventional configuration in which a secondary coolant is interposed, the secondary coolant 5 and the feed water are configured to directly exchange heat, so a secondary coolant is required. There is no need for any of the various types of equipment that would otherwise be required, which not only simplifies the configuration, but also effectively reduces the amount of materials needed to significantly reduce costs.

(2) In addition, since the heat exchanger tube 41 of the evaporator 31 has a double piping structure consisting of an inner heat exchanger tube 42 and an outer heat exchanger tube 43, isolation between the secondary coolant 5 and the water supply is ensured; - It is possible to reliably prevent accidents such as high pressure generation due to the reaction between the secondary coolant 5 and water (water-Na reaction), and accidents such as damage to structures or leaks of the secondary coolant 5, and secondary cooling It is possible to ensure the same safety as when a material is interposed.

(3) In addition, in the case of this embodiment, the circulation pump 22 is housed inside the reactor vessel 1, and only the evaporator 31 and the coolant pipes 23, 25 are outside the reactor vessel 1.
The external configuration (for example, piping configuration, etc.) of the reactor vessel 1 is greatly simplified, and the installation space can be reduced.

(4) Furthermore, since the circulation pump 22 of this embodiment is configured to suck the coolant 5 in the upper plenum 9, unlike a conventional tank type that sucks the coolant in the lower plenum, There is no liquid level in the plenum 10. In addition, since the liquid level in the upper plenum 9 is sufficiently high relative to the suction position of the circulation pump 2, there is no fluctuation in the liquid level due to the operation of the circulation pump 22, and even if a sufficient suction head (NPSH) is taken, the circulation pump 22 cannot be shortened. Therefore, a sufficiently high discharge pressure can be obtained even if the relatively large pressure loss occurring in the evaporator 31 is considered.

[Effects of the Invention 1] As detailed above, according to the nuclear reactor according to the present invention, the structure of the reactor, particularly the structure of the outside of the reactor vessel, can be simplified without increasing the size of the reactor vessel. Further, the disadvantages caused by not interposing the secondary cooling W material can be effectively eliminated by forming the heat transfer tube of the evaporator into a double piping structure.

[Brief explanation of the drawing]

Figures 1 to 4 are diagrams showing an example of a practical journey of the present invention.
The figure is a cross-sectional view showing the overall configuration of the fast breeder reactor, and Figure 2 is the first
Fig. 3 is a cross-sectional view of the evaporator, Fig. 4 is a detailed view of the part (■) in Fig. 3, and Fig. 5 shows the configuration of a conventional loop fast breeder reactor. FIG. 6 is a cross-sectional view showing the configuration of a conventional tank-type fast breeder reactor. DESCRIPTION OF SYMBOLS 1... Reactor vessel, vessel, 5... Coolant, 6... Reactor core, 22... Circulation pump, 23... Coolant inflow piping,
25... Coolant outflow pipe, 31... Evaporator, 41...
...heat exchanger tube, 42...inner heat exchanger tube, 43...outer heat exchanger tube. Applicant's agent Patent attorney Takehiko Suzue s2 Figure 3EJ Figure 6

Claims (2)

[Claims] (1) A reactor vessel that accommodates coolant and the reactor core, a circulation pump that is installed inside the reactor vessel and pressurizes the coolant that has passed through the reactor core and is heated, and a circulation pump that is installed outside the reactor vessel and that is The coolant pressurized by the circulation pump is introduced through the coolant outflow pipe and is exchanged with the steam system to generate steam, and the cooled coolant is transferred to the reactor via the coolant inflow pipe. 1. A nuclear reactor comprising: an evaporator that returns water into a container; and a heat transfer tube disposed within the evaporator that has a double piping structure and allows feed water to flow through an inner heat transfer tube. (2) The inside of the reactor vessel is divided into an upper plenum and a lower frennum by a partition wall, and the circulation pump sucks coolant from within the upper plenum. nuclear reactor.