JPH046492A - Tank-type fast breeder reactor - Google Patents

Abstract

PURPOSE:To reduce the quantity of material of a thin-wall structure of a reactor wall cooling system and to improve the seismic resistance thereof by a method wherein a bypass flow for cooling the inner wall surface of a reactor vessel is led by a piping for bypassing. CONSTITUTION:A primary coolant flowing out of a primary circulation pump 16 flows into a high-pressure plenum 25 through a communication pipe 20 and most of it flows into a reactor core 2 from the high-pressure plenum 25. The coolant heated to a high temperature in the reactor core 2 flows out into a high-temperature coolant accommodating vessel 5 and flows into an intermediate heat exchanger 17 from the window thereof, and it is subjected to heat exchange with a secondary coolant in the intermediate heat exchanger 17, so as to be cooled down. Then, it flows out into a low-temperature coolant area 21 from the outlet of the intermediate heat exchanger 17 and flows into the primary circulation pump 16. Meanwhile, part of the primary coolant of low temperature flowing in the high-pressure plenum 25 flows into a gap 22 between a low-temperature coolant channel forming wall 30 and a reactor vessel 1 through a piping 28 for bypassing, and it flows out of the gap 22 and flows into a coolant stay space 14. By the primary coolant of low temperature flowing through the piping 28 for bypassing, the inner wall surface of the reactor vessel 1 is kept in a state of low temperature and generation of a thermal stress by the high-temperature coolant is mitigated.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a tank-type fast breeder reactor equipped with a cooling structure for ensuring the integrity of the reactor vessel.

(Prior art) In general, a fast breeder reactor has a reactor core and a secondary coolant (usually liquid sodium) housed in a reactor vessel, and this secondary coolant is circulated through the reactor core to react with nuclear fuel in the reactor core. heated by. This heated primary coolant is led to an intermediate heat exchanger to exchange heat with a secondary coolant (also typically liquid sodium), which is then led to a steam generator to exchange heat with water. The superheated steam obtained here is sent to a turbine for driving a generator.

By the way, in this type of fast breeder reactor, it is necessary to design the reactor vessel in such a way that it can withstand high temperatures. Also,
It is also necessary to guide the high temperature primary coolant that has passed through the core to the intermediate heat exchanger without reducing its temperature.

Therefore, in recent years, a fast breeder reactor having a configuration as shown in FIG. 2 has been developed.

FIG. 2 shows a schematic configuration of a tank-type fast breeder reactor. In the figure, reference numeral 1 denotes a reactor vessel that accommodates a reactor core 2 and secondary coolant 3, and is shielded by an upper open roof slab 4 of this reactor vessel 1. A high-temperature coolant storage container 5 is disposed inside the reactor vessel 1 and supported by a core support structure 6 that supports the reactor core 2 . This storage container 5 has a gap 7 between the upper half 5A and the inner circumferential surface of the furnace container 1, and the lower half 5B
has a small diameter and its lowermost end is attached to the core support structure 6, and a conical part 5C slopes downward toward the center between the upper half 5A and the lower half 5B. .

Inside the furnace vessel 1, a low-temperature coolant flow path 9 is formed between the flow path forming plate 8 and the inner surface of the furnace vessel l. The flow path forming plate 8 has a flow port 10 located directly below the core 2, and has a circumferential wall soil portion as a double wall (inner circumferential wall 11A, outer circumferential wall 11B). ) 12 is opened to the low temperature coolant storage space I5.

An annular partition wall 13 centered around the core 2 is attached between the lower end of the double wall of the flow path forming plate 8 and the core support structure 6. This partition wall 13 is located on the outside of the high-temperature coolant container 5 and forms an annular coolant retention space 14 between it and the conical portion 5C of the high-temperature coolant container 50. Low-temperature coolant storage space 15 communicating with the lower end of 4
It forms the

A primary coolant three-ring pump 16 and an intermediate heat exchanger 17 are supported on the roof slab 4 . These circulation pumps 1
6 and the heat exchangers 17 are arranged alternately on the circumference around the core 2.

The primary coolant circulation pump I6 communicates with the coolant retention space 14 and passes through the inside of the cylindrical body 1B provided on the conical portion 5C.
Furthermore, it penetrates through the partition wall 13 and is introduced into the low-temperature coolant storage space 15 . The suction side is a coolant retention space 14.
The primary coolant 3 in the coolant retention space 14 is sent into the low temperature coolant storage space 15 by communicating with the low temperature coolant storage space 15 on the discharge side.

The intermediate heat exchanger 17 has a primary coolant inflow side located in the high temperature coolant storage container 5 and a primary coolant outflow side communicated with the low temperature coolant storage space 15 to provide primary cooling in the high temperature coolant storage container 5. It is configured to allow the material 3 to flow into the low temperature coolant storage space 15.

Next, the operation of the tank-type fast breeder reactor configured as described above will be explained.

Low-temperature coolant storage space 1 by primary coolant circulation pump 16
When the primary coolant 3 in 5 is pressurized, the secondary coolant 3
passes through the reactor core 2 as shown by the arrow a, is heated by the heat generated by the nuclear reaction of the uranium fuel in the reactor core 2, reaches the high temperature coolant container 5, and flows into the intermediate heat exchanger 17 as shown by the arrow. Here, the secondary coolant 3 transfers heat to the secondary coolant, is cooled and flows out into the low temperature coolant storage space 15 as shown by arrow C, and passes through the core 2 again into the high temperature coolant storage vessel 5. Repeat the cycle.

On the other hand, the primary coolant 3 in the low-temperature coolant storage space 15 pressurized by the secondary coolant circulation pump 16 moves up the low-temperature coolant flow path 9 as shown by arrow d, and crosses the outer circumferential wall 11B of the double wall portion. As shown by arrow e, the coolant flows over the inner and outer peripheral walls 11A and 118, and further flows out into the low-temperature coolant storage space 15.

By the way, in the tank-type fast breeder reactor configured as described above, the high-temperature secondary coolant that has passed through the reactor core 2 and is heated is accommodated in the high-temperature coolant storage container 5, The reactor vessel 1 will be kept at a relatively low temperature since the previous coolant will be in contact with it. Therefore, the design of the furnace vessel 1 can be facilitated. In addition, a partition wall 13 is provided on the outside of the high-temperature coolant storage container 5 to form a coolant retention space I4, so that the primary coolant existing in this space 1a reaches a high temperature inside the storage container 5 at a high temperature. It functions as a heat shield between the secondary coolant and the low-temperature secondary coolant in the low-temperature coolant storage space 15, and prevents the temperature of the coolant 3 in the high-temperature coolant storage container 5 from decreasing.

(Problems to be Solved by the Invention) As described above, the structure for forming the furnace wall cooling flow path includes the flow path forming plate 8, the inner peripheral wall 11A1 the outer peripheral wall 11B1, the baffle plate 19,
It is composed of many thin-walled structures such as the high-temperature coolant storage container 5A. Therefore, the method of cooling the furnace wall as a measure to reduce thermal stress in the vicinity of the liquid surface of the furnace vessel has the problem of increasing the amount of material and complicating the seismic design.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a tank-type fast breeder reactor in which the amount of thin-walled structures of the reactor wall cooling type is reduced and earthquake resistance is improved.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a method for creating a gap between a reactor vessel that houses a reactor core and a primary coolant and whose upper opening is closed with a loose slab, and the inner surface of this reactor vessel. a high-temperature coolant storage container disposed within the reactor vessel to accommodate the high-temperature coolant that has passed through the reactor core and suspended from the roof slab; a low-temperature coolant flow path forming wall that forms a coolant retention space between the furnace container and the furnace container, and a wall that forms a low-temperature coolant flow path and an inner wall surface of the furnace A plurality of bypass pipes connecting the gap and a high-pressure plenum of a core support structure that supports the reactor core, and support from a partition wall provided along the bypass pipes and partitioning between the high-pressure plenum and the inner wall of the reactor vessel. It is characterized by being equipped with a piping support.

(Function) Most of the primary coolant flows from the primary circulation pump through the communication pipe into the high-pressure plenum, and from the high-pressure plenum into the reactor core. It is heated in the core and flows into the intermediate heat exchanger where it exchanges heat with the secondary coolant.

On the other hand, a portion of the primary coolant flowing out from the high-pressure plenum flows through the bypass pipe and into the gap between the furnace vessel and the wall forming the low-temperature coolant flow path, cooling the inner wall surface of the reactor vessel and maintaining a low temperature state. . This low-temperature coolant relieves thermal stress in the furnace vessel. Furthermore, by using bypass piping, the number of conventional flow path forming plates and the like can be significantly reduced.

Furthermore, by supporting the high-temperature coolant storage container from the roof slab, the storage container bears the vibrational weight of the high-temperature coolant during earthquake resistance, thereby improving the earthquake resistance of the reactor vessel.

Furthermore, by providing the gas reservoir 27 outside the high-temperature coolant storage container, the insulation performance of the inside and outside of the storage container is improved.

(Example) An example of a tank-type fast breeder reactor according to the present invention will be described with reference to FIG. Note that the same parts in FIG. 1 as in FIG. 2 will be described with the same reference numerals.

In FIG. 1, a reactor core 2 is supported by a core support structure 6, and a secondary coolant 3 is accommodated in a reactor vessel 1. The upper opening of the furnace vessel 1 is closed by a roof slab 4. A high pressure plenum 25 is provided in the lower part of the reactor core 2, into which coolant from the primary circulation pump 16 flows through a communication pipe 20. -Next circulation pump 16
An intermediate heat exchanger 17 is provided around the core 2 in the furnace vessel 1 by penetrating the roof slab 4. A partition wall 13 is provided between the high-pressure plenum 25 and the lower inner surface of the reactor vessel 1, and the partition wall 13 defines an upper portion and a lower portion of the reactor core 2. The lower part of the partition wall 13 is a low temperature coolant area 21
The upper part forms a primary coolant retention space 14 .

A high-temperature coolant storage container 5 is provided above the core 2, and this container 5 is suspended from the roof slab 4. A gas stopper 27 is provided on the outer surface of the upper part of the container 5. There is a gap 22 between the furnace vessel 1 and the high temperature coolant storage vessel 5.
A low-temperature coolant flow path forming wall 30 is provided so as to have a wall 30, and a plurality of bypass pipes 28 are connected to the lower part of the gap between this wall 30 and the furnace vessel 1, and these pipes 28 are connected from the partition wall 13 to It is supported by a piping support 29. Note that the lower end of the bypass pipe 28 is connected to the high pressure plenum 25 in communication.

The lower end of the intermediate heat exchanger 17 is connected to the partition wall 13 and the bellows seal 2
It is sealed by 6. In the figure, reference numeral 23 is a cylinder surrounding the primary circulation pump, and 24 is a cylinder surrounding the intermediate heat exchanger.

Here, the secondary cooling member flowing out from the secondary circulation pump 16 flows into the high-pressure plenum 25 through the communication pipe 20, and most of the primary coolant flows into the reactor core 2 from the high-pressure plenum 25. The high-temperature coolant heated in the core 2 flows into the high-temperature coolant container 5, flows in through the window of the intermediate heat exchanger 17, and is cooled by exchanging heat with the secondary coolant in the intermediate heat exchanger I7. ,
It flows out from the outlet of the intermediate heat exchanger 17 into the low temperature coolant region 21 and flows into the primary circulation pump 16 . Then, it follows the circulation path from the communication pipe 20 to the high-pressure plenum 25 and the reactor core 2 again.

On the other hand, a part of the low-temperature primary coolant that has flowed into the high-pressure plenum 25 passes through the bypass pipe 28, flows into the gap 22 between the cold coolant flow path forming wall 30 and the furnace vessel 1, flows out of the gap 22, and is cooled. The material flows into the material retention space 14. Bypass piping 2
The inner wall surface of the furnace vessel 1 is maintained at a low temperature by the low-temperature primary coolant flowing through the reactor 8, and the generation of thermal stress caused by the high-temperature coolant is alleviated.

In this way, by guiding the cooling bypass flow that cools the inner wall surface of the furnace vessel 1 through the bypass piping 28, thermal stress near the liquid surface of the furnace vessel can be reduced.

In addition, a waste retainer 27 is provided on the outer surface of the upper part of the high-temperature coolant storage container 5.
By providing this, the insulation of the upper part of the coolant retention space I4 is improved, and it is possible to prevent the heat of the high-temperature coolant from being directly conducted to the inner wall surface of the furnace vessel 1.

"Effects of the Invention" According to the present invention, it is possible not only to reduce the thermal stress of the furnace vessel, but also to reduce the amount of thin-walled structures in the furnace wall cooling system, and to improve earthquake resistance.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a tank-type fast breeder reactor according to the present invention, and FIG. 2 is a longitudinal sectional view showing a conventional fast breeder reactor. 1... Reactor vessel 2... Core 3... - Secondary cooling member 4... Roof slab 5... High temperature coolant storage container 6... Core support structure 7... Gap 8... Flow path forming plate 9...low temperature coolant channel 10...flow port 11A...inner wall 11B...outer wall 12...annular region 3...partition wall 4...coolant retention Space 5...Low temperature coolant storage container 6...Next cooling member circulation pump 7...Intermediate heat exchanger body...Cylinder body 9...Baffle plate 20...Communication pipe 21...Low temperature Coolant area 22... Gap 23... Pump cylinder 24... Heat exchanger cylinder 25... High pressure plenum 2ε... Bellows seal 27... Gas reservoir 28... For bypass Piping 29... Piping support 30... Low-temperature coolant flow path forming wall (8733) Agent Patent attorney Yoshiaki Inomata (and others)
1 person) Figure Figure

Claims (1)

[Claims] High-temperature cooling that is disposed within the reactor vessel with a gap between the reactor vessel that accommodates the reactor core and primary coolant and whose upper opening is closed by a roof slab, and the inner surface of the reactor vessel, and that has passed through the reactor core. A coolant retention space is formed between a high-temperature coolant storage container that houses the material and is suspended from the roof slab, and a high-temperature coolant storage container that is disposed outside of the high-temperature coolant storage container, and A low-temperature coolant channel forming wall disposed inside the reactor vessel, a gap between the low-temperature coolant channel forming wall and the inner wall surface of the reactor vessel, and a high-pressure plenum of a core support structure that supports the reactor core are communicated with each other. A tank-type high-speed breeder characterized by comprising a plurality of bypass piping, and a piping support provided along the bypass piping and supported from a partition wall that partitions between the high-pressure plenum and the inner wall of the reactor vessel. Furnace.