JPS5811892A - Reactor container - 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 The present invention relates to a nuclear reactor vessel used, for example, with a liquid metal cooled nuclear reactor.

A fast breeder reactor that uses liquid metal such as liquid sodium as a coolant seals the upper opening of the reactor vessel body containing the core with a shielding plug, and also prevents the coolant from flowing above the free liquid level inside the reactor vessel body. Contains cover gas such as inert gas. The coolant that flows into the reactor vessel body from the coolant inlet pipe is heated in the reactor core, rises, and is taken out of the reactor vessel through an outlet nozzle attached to the reactor vessel body. ing. Therefore, the wall temperature of the reactor vessel body becomes high near the free liquid surface of the coolant, creating a large humidity gradient in the vertical direction.
This causes thermal stress.

Therefore, in order to reduce the occurrence of such thermal stress, a heat shielding pin is installed inside the reactor vessel body, and a cooling flow-resistant gap is formed between this pin and the inner surface of the reactor vessel body. Attempts have been made to make the temperature gradient on the inner surface of the vessel main body gentle by bypassing a portion of the low-temperature coolant before it passes through the core and allowing it to flow through this gap.

However, the above-mentioned liner is equipped with an internal nozzle to guide the high-temperature cooling water that has passed through the reactor core along with the exit nozzle. Since it is necessary to absorb the relative displacement in the tube axis direction that occurs between the tube and the outlet nozzle due to the influence of external factors, the structure is such that there is a small gap between the tube and the outlet nozzle so that they do not restrict each other. Therefore, a portion of the low-temperature coolant flowing through the above-mentioned coolant distribution gap leaks through this small gap and mixes with the high-temperature coolant that has passed through the core. In this case, not only will the cooling effect be reduced due to unnecessary leakage of the cooling water, but also
It also causes a decrease in the thermal efficiency of the plant.

Moreover, if cooling injuries having a large temperature difference are mixed in the vicinity of the outlet nozzle, thermal fluctuations will occur in this mixing area, which may have a negative impact on the structural integrity.

This invention was made based on the above circumstances, and its purpose is to alleviate the temperature gradient that occurs in the reactor vessel body (1), prevent the occurrence of thermal stress, and prevent leakage of coolant bypassed for cooling. The objective is to provide a nuclear reactor vessel that can prevent

That is, the present invention relates to a reactor vessel body and a liner that is provided inside the reactor vessel body and forms a coolant flow gap between the vessel body and the reactor vessel body.

an outlet nozzle through which the coolant flows out after passing through the reactor core; an internal nozzle that is inserted through the outlet nozzle and forms a small gap communicating with the cooling flow gap; By providing a coolant flow regulation means.

It is possible to flow low-temperature coolant to the inner surface of the reactor vessel body, which can alleviate temperature gradients, and also to suppress leakage of coolant bypassed for cooling purposes, thereby increasing thermal efficiency and reducing temperature differences. This is a reactor vessel that can prevent certain coolants from mixing together, and can also prevent the occurrence of thermal shock.

The present invention will be explained below based on an embodiment shown in the drawings. 1 in the figure shows the reactor vessel body of a liquid metal cooled nuclear reactor. Inside the reactor vessel body 1, a reactor core 3 is supported by a core support structure 2. Further, liquid sodium is contained within the reactor vessel body 1 as an example of a coolant 4. Further, the upper opening of the reactor vessel body 1 is sealed by a shielding plug 5.

Between this shielding plug 5 and the free liquid surface of the coolant 4, a cover gas space 6''4r is formed in which an inert gas is confined. A core upper mechanism 7 equipped with mechanisms and the like is attached.

Further, the reactor vessel body 1 is provided with a coolant inlet pipe 10 . This inlet f1θ is.

It is connected to the inflow chamber 2m of the core support structure 2, and the coolant is fed from the lower surface side of the core 3 through the flow distribution chamber 2b. Further, the reactor vessel body 1 is provided with an outlet nozzle 11. This outlet nozzle 1) takes out high-temperature coolant flowing out of the reactor core 3 to the outside of the reactor through an outlet pipe 12, and communicates with an upper plenum 13. Further, an inner cylinder 15 is installed between the reactor vessel body 1 and the reactor core 3, and a coolant bypass plenum 14 is formed between the inner cylinder ftHs and the reactor vessel body 1. The bypass plenum 14 communicates with the flow distribution chamber 2b.

A liner 18 is installed inside the reactor vessel body 1. This liner 18 includes a thin liner plate 18m,
It has a double structure consisting of a thick liner plate 18b on the inside thereof, and a coolant accommodation gap 19 is formed between these two liner plates 18m and 18b. Further, the liner 18 is supported by an upper support seat 20 and a lower support seat 2.

Then, the thin liner plate 111m and the reactor vessel main body 1
A coolant circulation gap 22 is formed between the two. This gap 22 communicates with the free liquid surface of the coolant 4 via an upper flow hole 23 formed in the upper support seat 2o.
It communicates with the bypass plenum 14 via a lower communication hole 24 formed in the lower support seat 21 . Note that a large number of these communication holes 23 and 24 are formed in the circumferential direction of the reactor vessel body 1, respectively. Also.

A communication hole 2 is provided at the upper end of the liner 18 to allow the coolant to flow out.
5 is formed.

An internal nozzle 28 is inserted inside the outlet nozzle 1 . This internal nozzle 28 is fixed to the thick liner plate 18b.

In addition, a small gap 29"40" is provided between the outlet nozzle 1 and the outlet nozzle 1 in order to absorb the relative displacement in the tube axis direction that occurs between the outlet nozzle 1 and the outlet nozzle 1 due to thermal effects.This small gap 29 is , and communicates with the above-mentioned coolant flow gap 22.

A labyrinth seal JO is provided in the small gap 29 as a coolant flow regulating means.

In other words, the labyrinth seal 30 has a large number of flange-like steps 301 arranged in the tube axis direction of the internal nozzle 2B. Therefore, the cooling gas that attempts to flow into the small gap 29 from the coolant distribution gap 22 is absorbed by these steps.
By passing between Oa..., a rapid pressure rise and a pressure drop occur and the energy is lost, so that leakage at the outlet portion 29a becomes extremely small.

Next, the operation of the reactor vessel having the above configuration will be explained. Most of the coolant introduced into the flow lid distribution chamber 2b through the inlet pipe 10 passes through the core 3, is heated, rises, flows out from the upper blemish 18, passes between the upper support seats 200,
Outflow from internal nozzle 28 into outlet tube 12 . The high-temperature coolant is then transported to an external device such as a heat exchanger (not shown), where it undergoes heat exchange to become low temperature, and returns to the inlet pipe 10 again.

On the other hand, a part of the coolant that has entered the flow distribution chamber 2b is introduced into the bypass plenum 14 at a predetermined flow rate, and flows into the coolant flow 1 m gap 22 through the lower flow hole 24. . Then, it rises within this gap 22 and the upper circulation hole 2
3 and exits from the communication hole 25 at the upper end of the liner 18.

Since the coolant introduced into the gap 22 in this manner is on the low-temperature cooling side before passing through the reactor core, the inner surface of the reactor vessel body 1 can be cooled by rising through the gap 22. Therefore, it is possible to suppress the temperature rise in the vicinity of the free liquid surface of the coolant through which the high-temperature coolant passes after passing through the reactor core, or in the vicinity of the outlet nozzle 11, thereby reducing the temperature gradient between the upper and lower sides of the reactor vessel body 1. It can be made gradual.

Also, there is a labyrinth seal between the outlet nozzle II and the internal nozzle 28? 0, the outlet nozzle 11
Even if a small gap 29 is provided between the inner nozzle 2B and the inner nozzle 2B in order to absorb the relative displacement between them, leakage of the coolant to the outlet portion 29a side through this small gap 29 can be prevented. It is something. Therefore, the low-temperature coolant flowing through the coolant distribution gap 22 can be effectively used for cooling the inner surface of the reactor vessel main body, and this can also contribute to improving the thermal efficiency of the entire Bukunto.

In addition, some cooling air flows through the small gap 29 to the outlet portion 2.
9a, but in this case the coolant flow a
The speed is suppressed to a low speed by the labyrinth seal 30, and since the labyrinth seal 30 functions as a heat radiation fin, the heat is sufficiently heated by the high temperature coolant flowing inside the internal nozzle 28 by the time it reaches the outlet part 29a. Ru. Therefore, coolants with different temperatures are not mixed, and it is possible to prevent thermal shock from occurring.

Moreover, according to the above embodiment, the two liner plates 18a, 1
Since the liner 18 has a double structure consisting of the liner plates 18a and 18b, there is an advantage that the heat insulating effect is further improved by the coolant trapped in the gap 19 between the liner plates 18a and 18b.

In the above embodiment, the step portion 3 is provided on the outer surface of the internal nozzle 28.
Although 0 m... is formed, for example, a labyrinth seal may be formed by forming a stepped portion on the circular surface of the exit nozzle 1 or on the inner surfaces of both.

In addition, the means for regulating the flow rate are not limited to those in the form of a coolant seal; for example, a narrow slit may be formed along the axial direction of the internal nozzle, or an orifice may be used to regulate the flow of coolant. may be configured.

As explained above, this invention provides a liner inside the reactor vessel body, forms a gap between the liner and the liner for flow of coolant, and forms a gap between the outlet nozzle communicating with this gap and the internal nozzle. A coolant flow regulating means is provided in the small gap. Therefore, low-temperature cooling can flow along the inner surface of the reactor vessel body, and the temperature gradient occurring in the reactor vessel body can be alleviated. At the same time, the gap ζ2 for coolant distribution can prevent leakage of the cooling gas.
It has great effects, such as reducing heat loss, preventing the occurrence of thermal shock due to mixing of coolants with different temperatures, and being effective in maintaining the integrity of the outlet nozzle.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a longitudinal sectional view of a nuclear reactor, Fig. 2 is an enlarged sectional view of the outlet nozzle portion, and Fig. 3 is an enlarged view of the ■ part in Fig. 2. . 1...Reactor vessel body, 3...Reactor core, 4...Cooling inspection. 1... Outlet nozzle, 18... Liner, 22...
Coolant distribution gap, 28...Internal nozzle, 29...Small gap. 30... Cubillin seal (cooling side flow regulation means).

Claims (1)

[Scope of Claims] α) A nuclear reactor vessel body containing a reactor core, a fin provided inside the reactor vessel body and forming a cooling circulation gap between the inner surface of the vessel body; an outlet nozzle that is attached to the vessel body and allows the coolant to flow out after passing through the core; and an internal nozzle that is inserted inside the outlet nozzle and forms a small gap between the outlet nozzle and the outlet nozzle that communicates with the coolant flow gap. and. A nuclear reactor vessel characterized in that the cooling is provided in a small gap between the outlet nozzle and the internal nozzle and is equipped with a flow regulating means. (2) The reactor vessel according to claim 1, wherein a labyrinth seal is used as the coolant flow regulating means.