JPH02222861A - Fast breeder reactor - Google Patents

Abstract

PURPOSE:To make a reactor vessel small in size and to enable prolongation of a period replacement of fuel by providing an electromagnetic pump outside a guard vessel and on the lateral side of an intermediate heat exchanger and by providing a vertically movable reflector on the lateral side of a reactor core. CONSTITUTION:A reflector 25 of beryllium or the like, a driving mechanism 26 thereof and an electromagnetic pump 27 are provided outside a reactor vessel 2. Primary sodium Na circulates through a reactor core 20, flows into an intermediate heat exchanger 22 from a primary inlet 30 and flows out of a primary outlet 31. Secondary Na flowing into the exchanger 22 from a secondary inlet 11 lowers and flows into a central riser 33 from a window 32 and flows out of a secondary outlet 14, and the primary Na is subjected to heat exchange in the meantime. Then, the primary Na coming out of the outlet 31 lowers through an annulus 34, passes through a flow rate mixing device 21 and enters the reactor core 20. The reflector 25, which is positioned below at the time of start of the operation, rises 26 gradually after a core fuel located below is burnt, so that fuel disposed above be burnt. According to this constitution, it is possible to make the vessel 2 small in size and to improve reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Industrial Application Field) The present invention relates to a fast breeder reactor that uses, for example, liquid metal sodium (hereinafter referred to as sodium) as a coolant.

(Prior art) The reactor structure and primary cooling system of a conventional tank-type fast breeder reactor will be explained with reference to FIG. is housed, and a core upper mechanism 4 and a rotating plug 5 are arranged above the core 3. Inside the core upper mechanism 4, there are control rods 6 for controlling the reactor core 3, and control rods 6 for controlling the temperature of the core 3. An assembly outlet thermometer 7 is installed to measure the temperature of the reactor core 3.
is supported from the reactor vessel 2 by a core support structure 8 . Sodium, which is a coolant, flows out of the core 3, flows into the primary intermediate heat exchanger 9, and flows out from the intermediate heat exchanger 1 volcano mouth 1 (>. In the intermediate heat exchanger, secondary sodium flows into the secondary intermediate heat exchanger 11, descends down the downcomer pipe 12, flows out through the downcomer window 13, flows out from the volcanic mouth 14,
During this time, heat exchange is performed with the primary sodium. Sodium flowing out from the intermediate heat exchanger primary outlet 10 is sucked in by the pump 15, passes through the furnace piping 16, flows into the high pressure plenum 17, and returns to the reactor core 3. Furthermore, in conventional tank-type nuclear reactors, it is necessary to replace the fuel constituting the reactor core 3 once a year, and for this purpose, a cask 18 for fuel replacement is installed.

(Problems to be Solved by the Invention) Since the reactor structure and primary cooling system of a conventional fast breeder reactor are configured as described above, safe and stable operation is possible. However, in recent years, there has been a demand for further safety improvements, simplification, and maintenance-free fast breeder reactors.

Therefore, there are issues to be improved in the following points.

(1) Miniaturize the reactor vessel and improve its reliability.

(2) To further improve reliability by not installing driving parts such as control rods and primary pumps in sodium.

(3) Extend the core fuel replacement period and significantly reduce maintenance work related to fuel replacement.

(4) For loop reactors, the reaction between sodium and water that occurs in the steam generator installed in the primary system will be eliminated.

(5) Improve inherent safety by reducing reactor output scale.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a fast breeder reactor having a reactor structure that does not require fuel exchange during its lifetime in a tank type reactor. Another object of the present invention is to provide a fast breeder reactor in which the heat exchanger installed in the primary system of a loop reactor is a heat exchanger using sodium and gas, and has a cooling system that eliminates the reaction between sodium and water.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, a fast breeder reactor according to the present invention includes a reactor core and an intermediate heat exchanger in a reactor vessel and a guard vessel in a tank type nuclear reactor. In preparation, outside the guard vessel,
It is characterized by having an electromagnetic pump on the side of the intermediate heat exchanger, and a reflector made of beryllium or the like that can move up and down on the outside of the guard vessel and on the side of the core. In addition, a loop reactor has a reactor core inside the reactor vessel and guard vessel, and is equipped with a beryllium reflector that can move up and down on the outside of the vessel and on the side of the core, and the sodium that flows out from the reactor vessel is heat exchanged. The sodium that flows into the sodium gas heat exchanger with improved performance and flows out of the heat exchanger is characterized by flowing into the reactor by an electromagnetic pump installed outside the piping.

(Function) According to the fast breeder reactor according to the present invention, the reactor vessel has a diameter of 1 m to 1.5 sides at an output scale of 50,000 to 100,000 KWe,
Container reliability is greatly improved. Furthermore, since there are no driving parts such as control rods and primary pumps in the sodium tank, the reliability of the operating equipment is greatly improved. In addition, by sequentially moving reflectors such as beryllium, combustion of the core fuel is promoted only in areas where there are reflectors such as beryllium, and combustion is suppressed in other areas. By slowly moving the reflectors, fuel Eliminates the need for replacement and greatly improves maintainability.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an elevational sectional view showing a first embodiment of the present invention.

In the figure, the same parts as in FIG. 6 are designated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

As shown in FIG. 1, a reactor core 20 is placed inside a reactor vessel 2 surrounded by a guard vessel 1. A suspension shell 24 for suspending the flow mixer 21, the intermediate heat exchanger 22, and the reactor core 20 and intermediate heat exchanger 22 from the reactor vessel upper structure 23 is installed. Outside the reactor vessel 2, there is a reflector 25 made of beryllium or the like, its drive mechanism 26, and an electromagnetic pump 27.
is installed. A control system 29 for the cover gas 28 is installed in the reactor vessel upper structure 23 . The primary sodium flows out of the core 20, flows into the intermediate heat exchanger 22 from the intermediate heat exchanger 1 fire inlet 30, and flows into the intermediate heat exchanger 22 through the intermediate heat exchanger primary outlet 3.
Flows from 1.

In the intermediate heat exchanger 22, secondary sodium flows from the secondary inlet 11, descends through the intermediate heat exchanger 22, flows into the central riser pipe 33 through the window 32, and rises within the central riser pipe 33, 2 Secondary sodium flowing out from the washing outlet 14 and 1
Sodium exchanges heat. Intermediate heat exchanger 1 washing outlet 31
The sodium flowing out from the reactor core 20 flows down the annulus 34, passes through the flow mixer 21, and enters the reactor core 20. A reflector 25 made of beryllium or the like is installed below the reactor core 20 at the start of operation, and burns the core fuel disposed below. Thereafter, the core fuel installed above is also burned by gradually driving it upward using the drive mechanism 26.

Therefore, according to this embodiment, the reactor vessel 2 is significantly smaller than the conventional reactor vessel, and the reliability of the reactor vessel is improved. Furthermore, since the core is controlled and the primary sodium is driven from outside the vessel, the reliability of the drive unit is improved. Roughly, since combustion progresses gradually in the core 20,
There is no need to change fuel during operation, greatly improving maintainability.

Next, a second embodiment of the present invention will be described with reference to FIG.

This second embodiment changes the primary and secondary natrium flow path paths of the first intermediate heat exchanger 22 shown in FIG.
The bath was designed to raise primary sodium once and then lower it while exchanging heat. Note that the same parts in FIG. 2 as in FIG. 1 are designated by the same reference numerals, and the explanation of the overlapping parts will be omitted. That is, in FIG. 2, the primary sodium flowing out from the reactor core 20 passes through the riser pipe 41 and reaches the intermediate heat exchanger 2.
Rise within 2. After rising, the primary sodium flows out from the primary sodium window 42 and descends inside the intermediate heat exchanger 22,
It flows out from the first translation exit 43. Secondary sodium enters from the secondary population 11 , passes through the inlet plenum 44 , through the heat transfer tubes 45 , enters the outlet plenum 46 , and exits from the secondary sodium outlet 14 .

This second embodiment also has a reactor vessel 2 similar to the first embodiment.
can be made more compact. Furthermore, in this embodiment, the sodium on the primary side exchanges heat with the secondary sodium in the heat exchanger, and the cooled sodium falls in the direction of gravity, so that a natural flow path bus is formed.

FIG. 3 shows a third embodiment of the present invention applied to a loop type nuclear reactor. In FIG. 3, a reactor core 20. Furnace piping 50. An outlet pipe 51 is installed. A reflector 25 made of beryllium or the like and its drive unit 26 are installed outside the reactor vessel 2, as in the above embodiment. The reactor vessel 2 is connected to a sodium gas heat exchanger 53 via piping 54. Piping 54 is connected to a header 55, piping 56 is connected to header 55, and piping 56 is connected to sodium gas heat exchanger 53. A pipe 57 is connected below the sodium gas heat exchanger 53, and the pipe 57 connects to the furnace pipe 50 and the joint 5.
Connected by 2. A gas downcomer 58 and a gas outlet 59 are installed in the sodium gas heat exchanger 53 .

Figures 4 and 5 show a sodium gas heat exchanger 53.
The heat transfer part is shown in an enlarged partial side cross-sectional view.

Sodium descends inside the heat exchanger tube 60, and gas rises outside the heat exchanger tube 60. Metal particles 61 are placed on the outside of the heat exchanger tube 60.
is filled. As is clear from the plan view of FIG. 5, the heat exchanger tube 60a is connected to the adjacent heat exchanger tube 60b by a plate 62. In this way, the heat transfer performance to the gas is significantly improved, and the heat exchanger can be made more compact.

In this embodiment, the reactor vessel is made more compact than in the first embodiment. In the sodium gas heat exchanger, even if the heat exchanger tube 60 leaks, it will not react like a conventional steam generator (there is no reaction between lithium and water, and the safety is significantly improved.

[Effect of the invention] According to the present invention, the following effects are achieved.

(1) In order to control the reactor core from outside the reactor vessel, an intermediate heat exchanger can be placed above the reactor core. As a result,
The reactor vessel is significantly more compact and the reliability of the reactor vessel is improved.

(2) Since there is no driving part in the sodium, the operability of the plant is improved. It also has excellent maintainability.

(3) Since the reactor core burns slowly by driving a reflector such as beryllium to the top, there is no need to change fuel during plant operation, which significantly improves maintainability.

(4) When applied to a loop reactor, there is no reaction between sodium and water, significantly improving safety.

[Brief explanation of the drawing]

1 and 2 are elevational views showing respective embodiments of the fast breeder reactor according to the present invention, FIG. 3 is a system diagram showing an example in which the present invention is applied to a loop reactor, and FIG. 4 5 is an enlarged sectional view showing the heat transfer section of the heat exchanger in FIG. 2, and FIG. 6 is an elevational view showing a conventional fast breeder reactor. 2...Reactor vessel 2G...Reactor core 21...Flow mixer 22...Intermediate heat exchanger 23...Reactor upper structure 24...Hanging shell 26...Reflector drive mechanism 27 ... Electromagnetic pump 28 ... Cover gas 29 ... Control system 30 ... 1 Fire inlet 31 ... Primary outlet 32 ... Window 33 ... Central riser pipe 34 ... Annulus 41 ... ...Riser tube 42...Primary sodium window 43...Primary outlet 44...Inlet plenum 45...Heat transfer tube 46...Outlet plenum 50...Furnace piping 51...Outlet piping 52...Joint portion 53...Intermediate heat exchanger 54...Piping 55...Headers 56, 57...Piping 58...Down pipe 60...Heat transfer tube 61...Metal powder 62... Board (8733) Agent Patent Attorney Yoshiaki Inomata (and others)
1 person) $ 1 ↑ ↑ ↑ ↑ Tea diagram No. 2

Claims (2)

[Claims] (1) A reactor vessel, a reactor core that is controlled by driving a reflector up and down from the outside of the reactor vessel, and an intermediate heat exchanger disposed above this core; and a fast breeder reactor, wherein the intermediate heat exchanger is supported by a suspension shell from the reactor vessel upper structure, and an annulus portion is provided on the outside of the suspension shell. (2) A reactor vessel, a reactor core controlled by driving a reflector up and down from outside the reactor vessel, and a heat exchanger outside the reactor vessel, the heat exchanger being a heat exchanger. A fast breeder reactor characterized in that a coolant flows inside the heat transfer tubes, metal particles are filled outside the heat transfer tubes, and each of the heat transfer tubes is connected by a plate.