JPS6371690A - Tank type 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 OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to high>V breeder reactors, and more particularly to tank-type fast breeder reactors equipped with an intermediate heat exchanger within the reactor vessel.

(Conventional technology vT) Tank-type fast breeder reactors generally use liquid metallic sodium as primary and secondary coolants, and the primary sodium heated in the reactor core is guided to an intermediate heat exchanger installed in the reactor vessel. It exchanges heat with the secondary sodium, and the cooled primary sodium is sent back to the reactor core.

Fig. 3 shows a schematic configuration of a conventional tank-type fast breeder reactor, in which a reactor core 1a is provided inside a reactor vessel 1, and a roof slab 2 is installed in the upper part of the reactor core 1a. The inside of the reactor 1 is filled with primary sodium 3 and is partitioned by a partition wall 4 into an upper plenum 5 and a lower plenum 6.The reactor core section 1a is provided at the center of this partition wall 4,
A core upper mechanism 7 is provided on the roof slab 2 above a.

A plurality of intermediate heat exchangers 9 and a plurality of intermediate heat exchangers 1 are installed around the core 1a.
An 11M circulation pump 10 connects the partition wall 4 and the roof slab 2.
It is set up through 11 channels. The circulation pump 10 includes a motor 11 and an impeller 12 , and the discharge side of the circulation pump 10 communicates with a high-pressure plenum 14 via an inlet pipe 13 .

The intermediate heat exchanger 9 heats a shroud 15, a secondary sodium inlet pipe 16 and a secondary sodium outlet pipe 17 having a double pipe structure arranged coaxially in the center thereof, primary sodium 3, and secondary sodium 18. Multiple replaceable heat transfer tubes 1
It also includes an upper tube sheet 20 and a lower tube sheet 21 that support each heat exchanger tube 19.

A primary sodium through hole 22 for sucking in the primary sodium 3 is provided in the upper part of the shroud 15, and a primary sodium outlet nozzle 23 is provided in the lower part of the shroud 15.
is provided. The secondary sodium outlet pipe 17 is provided with a secondary sodium inlet hole 24 and a secondary sodium outlet hole 25 for allowing the secondary sodium 18 to enter and exit the heat transfer tube 19 side.

In the tank-type fast breeder reactor configured as described above,
The primary sodium 3 in the upper plenum 5 flows into the intermediate heat exchanger inlet plenum 27 through the primary sodium rotor 22, flows through the heat exchanger tubes 19 from the upper tube sheet 20, and flows through the lower tube sheet 21 and the primary sodium outlet nozzle 23. It flows into the lower plenum 6 through the.

The primary sodium 3 in the lower plenum 6 is circulated by a circulation pump 10
The rotation of the impeller 12 causes the air to be fed into the high pressure plenum 14 through the inlet pipe 13.

Thereafter, the primary thorium 3 is flushed through the reactor core 1a and is heated by the heat generated in the reactor core 1a.

The heated primary sodium 3 collides with the lower end surface of the upper core structure 7 above the core portion 1a, changes the flow in a radial direction, and flows into the intermediate heat exchanger inlet plenum 27 through the primary sodium artificial inlet 22.

On the other hand, the secondary sodium 18 is connected to the secondary sodium inlet pipe 16
The sodium is guided downward through the secondary sodium inlet hole 24 and flows into the heat transfer tube 19 side, where it exchanges heat with the primary sodium 3 via the heat transfer tube 19. The secondary sodium 18 whose temperature has been raised by heat exchange returns to the secondary sodium outlet pipe 17 through the secondary sodium outlet hole 25 and is guided upward within the secondary sodium outlet pipe 17.

Thereafter, the secondary sodium 18 is led to a secondary system heat exchanger (not shown) outside the reactor vessel 1, where it radiates heat, and is then pressurized by a secondary system pump (not shown), and is again transferred to the secondary system heat exchanger (not shown). into the sodium inlet tube 16.

(Problems to be Solved by the Invention) In the tank-type fast breeder reactor configured as described above, the primary sodium artificial through holes 22 provided in the intermediate heat exchanger 9 are It is provided below the free liquid level 28 of.

Therefore, when the primary sodium 3 flows from the upper plenum 5 to the intermediate heat exchanger 3 input loop plenum 27, the flow is throttled by the primary sodium inlet holes 22, the flow velocity increases, and the static state near the primary sodium artificial through holes 22 increases. Pressure decreases.

If the degree of static pressure drop is significant, the upper plenum 5
A vortex is generated from the free liquid level 28 of the primary sodium chloride toward the primary sodium artificial permeation hole 22, and the cover gas 29 covering the primary sodium 3 is drawn into the primary sodium 3. If the primary sodium 3 containing the cover gas 29 flows into the reactor core 1a via the intermediate heat exchanger 9 and the circulation pump 10, there is a risk that the reactor output will increase.

As a means to prevent such entrainment of the two cover gases, it has been proposed to provide the primary sodium artificial through hole 22 deeper than the free liquid level 28 of the primary sodium, or to widen the frontage area of the primary sodium artificial through hole 22.
.

However, if the primary sodium artificial hole 22 is provided sufficiently deep from the free liquid level 28 of the primary sodium cum, the intermediate heat exchanger inlet plenum 27 becomes longer, which increases the size of not only the intermediate heat exchanger 9 but also the reactor vessel 1. In addition, when the opening area of the primary sodium inlet hole 22 was increased, the mechanical strength of the shroud 15 deteriorated, which caused problems with the reliability of the intermediate heat exchanger 9. .

The present invention was made in consideration of the above-mentioned circumstances, and does not cause an increase in the size of the intermediate heat exchanger or deterioration of mechanical strength.
An object of the present invention is to provide a tank-type fast breeder reactor that can reduce the static pressure near the primary sodium artificial hole, prevent entrainment of cover gas, and prevent an increase in reactor output.

(Structure of the Invention) (Means for Solving the Problems) The present invention partitions the interior of a nuclear reactor vessel into an upper plenum and a lower plenum with 14 walls, and provides an intermediate heat exchanger penetrating the partition wall to In a tank-type fast breeder reactor where the reactor vessel is filled with primary sodium, the primary sodium artificial through hole provided to flow the primary sodium from the upper plenum into the intermediate heat exchanger is located at the free liquid level of the primary sodium. 82 +-j over the top and bottom of the image.

(Function) Since the primary sodium inlet hole is provided (opened) above and below the free liquid level of the primary sodium, the primary sodium inflow velocity in the vertical and depth directions of the primary notorium artificial hole becomes almost uniform. Therefore, the vertical static pressure gradient in the vicinity of the primary sodium inlet through hole is eliminated, and the generation of vortices and the entrainment of the cover gas due to the generation of vortices as in the prior art are prevented.

(Example) An example of a tank-type fast breeder reactor according to the present invention will be described with reference to FIGS. 1 and 2.

Since the overall configuration of the present invention is not different from the conventional one as shown in FIG. 1, the same reference numerals are given and the description thereof will be omitted.

In FIG. 1, the intermediate heat exchanger 9 includes a shroud 15,
Secondary sodium inlet pipe 1 coaxially arranged in its center
6 and secondary sodium outlet pipe 17, a large number of heat transfer tubes 19 provided to be able to exchange heat between primary sodium 3 and secondary sodium 18, and an upper tube plate 20 and lower tube supporting each heat transfer tube 19. A plate 21 is provided.

As shown in FIG. 2, in the upper part of the shroud 15, primary sodium artificial permeation holes 22A are provided above and below the free liquid level of the primary sodium. Therefore, the free liquid level 28 of primary sodium in the upper plenum 5 and the free liquid level 28 of primary sodium in the intermediate heat exchanger inlet plenum 27 are continuous. In addition, the upper plenum 5
The cover gas 29 of the intermediate heat exchanger inlet plenum 27 is in communication with the two cover gases of the intermediate heat exchanger inlet plenum 27.

The secondary sodium outlet pipe 17 is provided with a secondary sodium artificial through hole 24 and a secondary sodium outlet through hole 25 for allowing the secondary sodium 18 to enter and exit the heat transfer tube 19 side, as in the prior art.

In the tank-type fast breeder reactor configured as described above,
When the primary sodium 3 in the upper plenum 27 passes through the primary sodium artificial through hole 22A and enters the intermediate heat exchanger JjJI three-person lopletero plenum, the primary sodium 3 flows in the vertical direction (depth direction) of the primary sodium artificial through hole 22△. The flow rate becomes almost uniform.For this reason, the primary sodium artificial through hole 22△
There is also no vertical static pressure gradient in the vicinity, preventing the generation of vortices and the troughing of the cover gas that accompanies the generation of vortices, as in the conventional case.

In the embodiment described above, the primary sodium inlet hole 22A is rectangular, but it may be circular or the like as long as it is provided above and below the free liquid level 28 of the primary sodium.

〔Effect of the invention〕

As explained above, the tank type according to the present invention? In the 5-speed breeder reactor, the primary sodium 1-lium inlet hole is provided above and below the free liquid level of the primary sodium, eliminating the vertical static pressure gradient near the primary sodium inlet hole, and eliminating the need for a conventional cover. This has the effect of preventing an increase in reactor output due to gas entrainment.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of a tank-type fast breeder reactor according to the present invention, Fig. 2 is a diagram showing the state of the primary sodium artificial hole in the above embodiment, and Fig. 3 is a diagram showing a conventional tank-type fast breeder reactor. ! ;1
) is a diagram showing a furnace. DESCRIPTION OF SYMBOLS 1... Reactor vessel, 1a... Reactor core, 3... Primary sodium, 4... Partition wall, 5... Upper plenum, 9
...Intermediate heat exchanger, 15...Shroud, 16...
-Primary sodium inlet piping, 17...Primary sodium i/rium outlet piping, 18...Secondary sodium, 19...Heat transfer tube, 20...Upper tube plate, 21...Lower tube plate, 22
．． 22A...Primary sodium artificial through hole, 23...Primary sodium outlet nozzle, 24...Secondary sodium inlet hole, 25...Secondary sodium outlet hole, 27...
- Intermediate heat exchanger inlet plenum, 28...free liquid level of primary sodium, 29...cover gas. Representative Patent Attorney Noriyuki Chika Yudo Hiroshi Mitsumata Figure 1 Figure 3

Claims (1)

[Claims] The inside of the reactor vessel is divided into an upper plenum and a lower plenum by a partition wall, and an intermediate heat exchanger is installed through the partition wall. A tank-type fast breeder reactor characterized in that a primary sodium inlet hole provided for flowing primary sodium into an intermediate heat exchanger is provided above and below a free liquid level of primary sodium.