JPS63315987A - Reactor vessel of fast breeder - Google Patents

Abstract

PURPOSE:To uniformly cool a reactor vessel cylinder so as to minimize thermal stress and to improve the nondefectiveness of the structure by passing an inert gas such as gaseous argon to the inside of the reactor vessel at the time of tripping. CONSTITUTION:A cylindrical partition wall 18 is provided to the inside of the reactor vessel cylinder 1B apart at a prescribed spacing therefrom and an annular gas header 19 along the reactor vessel cylinder 1B is provided to the lower side of the partition wall. Plural pieces of gas supply pipes 20 are circumferentially mounted to the gas header 19 in order to supply the gas thereto. Plural air bubble risers may be circumferentially provided between the inside cylinder or the reactor vessel cylinder 1B and the partition wall 18 on the inner side of the wall 18. Then, many air bubbles force Na upward and, therefore, a coolant is sucked from below the hot pool and flows over the top end of the wall 18 so as to be circulated and supplied atop the hot pool. The thermal stress generated in the reactor vessel is thereby relieved and the non-defectiveness of the structure is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a thermal shielding device for a fast breeder reactor that uses liquid metal such as liquid sodium as a coolant.

(Prior Art) Generally, a fast breeder reactor, such as a tank type fast breeder reactor, is constructed as shown in FIG. FIG. 8 is a vertical cross-sectional view showing a schematic configuration of a tank-type fast breeder reactor.

In the figure, reference numeral 1 indicates a reactor vessel, and this reactor vessel 1
A safety container 2 is provided outside.

These reactor vessel 1 and safety vessel 2 were sent to Linga in the evening.
It is installed in the reactor building 4 via.

A roof slab 5 is provided to close the upper opening IAk of the reactor vessel 1. This roof slab 5 is
It is composed of a fixed plug 5A, a large rotation plug 5B rotatably attached to the fixed plug 5A, and a small rotation plug 5C rotatably attached to the large rotation plug 5B. A reactor core 6 and a coolant 7 such as liquid sodium are housed within the reactor vessel 1, and the reactor core 6 is supported by a core support structure.

Above the reactor core 6, a core upper mechanism 9 is provided through which the small rotating plug 5C (1) passes.In this core upper mechanism 9, a control rod drive 1j+ mechanism (not shown) is provided. The control rod drive mechanism adjusts the degree of insertion of control rods (not shown) into the reactor core 6 to control the core output.
The interior of the reactor vessel 1 is partitioned into an upper section by a partition wall 10, with a hot pool 11 formed on the L side and a cold pool 12 formed on the lower side. The coolant 7 that has reached a high temperature after passing through the core 6 flows through the hot pool IH, passes through the intermediate heat exchanger 13, exchanges heat with the secondary coolant, and flows out into the cold pool 12. This coolant 7 is the circulation pump 1
4, the fuel is transferred to the lower part of the reactor core 6 via the circulation pump discharge pipe 15. Note that the discharge piping 15 is connected to the circulation pump 14 and the core support l! & It is fixed to structure 8.

The core support mechanism 8 is suspended from the roof slab 5 via a suspension 114416, and even if the roof slab 5 vibrates, both the core 6 and the core upper mechanism 9 vibrate.
Prevent relative displacement between the two.

In the figure, reference numerals 17 are flow holes, and the coolant 7 flowing out from the upper surface of the core 6 flows through these flow holes 17.1.
7... flows into the hot pool 11.

When the reactor trips and reaches M1 shutdown, the control rods are inserted into the reactor core, the amount of heat generated in the reactor core decreases, and the temperature of the coolant coming out to the hot pool 11 decreases. At this time, the flow rate of the circulation pump 14 is switched from rated operation to small flow operation.

FIG. 9 shows the state of temperature distribution in the hot pool 11 after the reactor trip, obtained by the above operation. The temperature distribution at the height of the hot pool after a reactor trip is ■,
Changes over time in the order of ■ and ■. Because the lower part of the hot pool is cold and the upper part is hot, heat transfer by natural convection is difficult to occur, and the boundary with a temperature gradient remains as it is.
You will be moving slowly in that direction.

(Problem to be Solved by the Invention) The temperature gradient in the height direction of the hot pool shown in Figure 9 affects the temperature of 711 N degrees in the St sub-reactor space 11kll13 which is in contact with the hot pool, and +t)4 Ill
also has a temperature gradient almost similar to that shown in Fig. 9. If such a temperature gradient occurs in the reactor vessel body IB, which has a large diameter cylindrical shape, the thermal stress will be extremely excessive, and the maximum thermal stress will occur especially near the bending point of the temperature gradient, causing the reactor vessel body This will have a negative impact on the integrity of IB structure-E.

The present invention has been made in view of these points, and provides a reactor vessel for a fast breeder reactor that can alleviate the thermal stress of the reactor vessel shell and improve the integrity of the reactor vessel on its sideways. The purpose is to provide.

[Structure of the invention]

(Means for solving the problem) The I'l (child reactor vessel) of the fast breeder reactor of the present invention includes a cylindrical partition wall provided at a predetermined distance from the inner surface of the reactor vessel, and a cylindrical partition wall provided at a predetermined distance from the inner surface of the reactor vessel. It is characterized by comprising a gas header provided below and a gas supply pipe connected to the gas header. Further, in addition to the above configuration, the present invention is characterized in that a cylindrical cylinder is further provided inside the partition wall at a predetermined interval.

(Function) In the present invention, it is possible to extremely reduce the thermal stress in the reactor vessel shell caused by the temperature gradient of the coolant in the hot boule after a reactor trip.

In other words, the temperature gradient that occurs in the coolant in the hot pool after the child furnace trips in j)'' is low at the bottom and high at the top;
Bubbles generated by flowing an inert gas such as argon gas inside the reactor vessel rise only during a trip.

The rising force of these bubbles pushes up the coolant in this area, and the low-temperature coolant from the hot pool flows in from below, allowing uniform cooling of the reactor vessel shell, resulting in a uniform temperature distribution in the reactor vessel body. becomes.

In this way, in the present invention, the temperature distribution of the Dx sub-reactor vessel shell is uniform even during a reactor trip, and the thermal stress of the reactor vessel shell can be kept to a minimum.
The structural integrity of the sub-reactor vessel is greatly improved.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG. 1 and FIG. 2, which shows a main part A of FIG. 1 in an enlarged manner.

Note that the same parts as in the prior art are given the same reference numerals.

In this embodiment, a cylindrical partition wall 18 is provided at a predetermined interval inside the reactor vessel body IB, and a ring-shaped gas header 19 is provided below the partition wall along the reactor vessel body.
will be established. In order to supply gas to this gas header 19, a plurality of gas supply pipes 20 are installed in the circumferential direction. Also the third
In addition to the structure described in -, the figure shows a partition wall 18 as another embodiment.
A cylindrical inner tube is sunk inside.

The other 1M components are formed in the same manner as before.

Next, the operation of this embodiment will be explained.

The temperature distribution of the coolant in the hot boule 1, which occurs after a reactor trip, affects the temperature distribution of the reactor vessel body IB and significantly increases its thermal stress.

In this embodiment, the temperature distribution of the child reactor vessel body 1B is not affected by the temperature distribution of the coolant in the hot boule 11.

After a reactor trip, inert gas such as argon gas is sent from the gas supply pipe 20 to the bubble generation hole 19 of the ladder 19.
Generate bubbles from a. These many bubbles rise between the reactor vessel 1f'A 111 and the partition wall 18 due to their buoyancy. At this time, the sodium in this area is pushed upward by air bubbles. That is, the coolant is sucked in from below the hot pool, overflows from the upper end of the partition wall 18, and is circulated and supplied to the upper surface of the hot pool.

Therefore, r): After the child furnace 1-rip, the hot pool part is the 5th
] When the temperature distribution reaches the temperature distribution shown in ■ in the figure, by supplying argon gas, the coolant at the bottom of the hot boule is sucked from below the partition wall 18, and the reactor vessel l1lI41
Since B is always cooled to a uniform temperature with no temperature gradient over the height direction, there is no discontinuous temperature gradient in the hot boule portion.

Furthermore, as shown in FIG. 3, when an inner cylinder is provided.

At the start of gas supply, it is effective to reduce as much as possible the temperature change in the reactor vessel body IB when the low-temperature coolant at the bottom of the hot pool is sucked in and flows into the reactor vessel 11r41 [1. It has a structure that exchanges heat with the hot pool's coolant through an inner cylinder without flowing it.

As described above, according to one embodiment, a simple groove if! i significantly alleviates thermal stress in the reactor vessel and improves its structural integrity.

Next, other embodiments will be described. Figures 4 and 5 are
A plurality of bubble riser pipes 30 are provided in the circumferential direction between the reactor vessel shell IB and the partition wall 18, and the bubbles are made to rise along the bubble riser pipes 30, and the rise of the bubbles causes the coolant to rise. It allows fluid to flow and cools it.

6 and 7, the space between the reactor vessel shell IB and the partition wall 18 is partitioned into small cells by a bubble partition wall 40, and the upward force of the coolant due to the rise of the bubbles is increased.

C Effects of the invention] Since the reactor vessel of the fast breeder reactor of the present invention is configured as described above, the thermal stress generated in the reactor vessel is significantly alleviated, and the structural integrity of the reactor vessel is improved. It has great effects.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a fast breeder reactor to which an embodiment of the reactor vessel of the fast breeder reactor of the present invention is applied, and FIG.
3, 4 and 6 are partial detailed sectional views showing other embodiments of the present invention, FIG. Figure 6 is a cross-sectional view taken along line L-L in Figure 6, Figure 8 is a longitudinal cross-sectional view showing a conventional fast breeder reactor, and Figure 9 shows the change in coolant temperature distribution in the hot boule after a reactor trip.
・It is XL. 1...) M child furnace vessel 18... Partition wall 19...
・Gas header 20... Gas supply management agent Patent rules Ken Chika Yudo Ken Daishimaru Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 8

Claims (1)

[Claims] A reactor vessel for storing liquid coolant, a partition wall installed at a predetermined interval inside the reactor vessel and at the liquid level of the liquid coolant, and a gas header provided below the partition wall. , and a gas supply pipe connected to the gas header to supply gas thereto.