JPS60147691A - Fast breeder reactor - 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 an improvement in a fast breeder reactor in which the coolant, hot liquid metal, penetrates from the bottom of the reactor vessel upward through the reactor core.

To explain the conventional fast breeder reactor with reference to Figure 1.2.6, (1) is the reactor vessel wall, and (2) is the reactor core (not shown).
an inner cylinder surrounding the upper part and forming a buffer area between the reactor vessel wall (1); (3) a low-temperature liquid metal;
)(5) is a high-temperature liquid metal, and in a fast breeder reactor, the reactor trips (the main nuclear reaction stops) during operation.
When the output decreases, the temperature of the liquid metal changes rapidly because the heat capacity of the liquid metal used as a coolant is small. This rapid temperature change of the liquid metal causes the reactor vessel wall (
1), the heat capacity as a structural phase of the reactor vessel is large, so the thermal response is delayed and large thermal stress is likely to occur in the reactor vessel wall (1). Therefore, an inner cylinder (2) is installed at a location where such a sudden excessive heat is likely to be applied to prevent the sudden excessive heat from being applied to the reactor vessel wall (1).

However, when a thermal stratification phenomenon (stone) occurs, the low-density high-temperature liquid metal (4) on the upper side and the high-density low-temperature liquid metal (3) on the lower side separate and become stable in the state shown in Figure 2. . However, at this time, the liquid gold A (5) between the inner cylinder (2) and the reactor vessel wall (1) remained at high temperature, and the inner cylinder (2)
From the lower side of the inner cylinder (2), from the relationship of the density difference with the low temperature liquid metal (3) inside the inner cylinder (2) (because the density of the low temperature liquid metal (3) inside the inner cylinder (2) is higher). The low-temperature liquid metal (3) enters the outside, and the high-temperature liquid metal (5) on the outside of the inner cylinder (2) moves from the top of the inner cylinder (2) into the inner cylinder (2) in a piston style.
(See the arrow in Figure 6).

This causes the problem that the strike 2 is formed again on the outside of the inner cylinder (2), and the inner cylinder (2) no longer performs its original thermal shock mitigation function.

The present invention addresses the above-mentioned problems in a fast breeder reactor in which a high-temperature liquid metal coolant flows upwardly through the reactor core from below the reactor vessel. A fast breeder reactor is characterized in that the reactor has an inner cylinder that forms a buffer region between the inner surface of the reactor and the inner cylinder, and the upper end of the inner cylinder projects from the liquid metal level into the cover gas space, and the purpose of the reactor is The object of the invention is to provide an improved fast breeder reactor that can avoid severe thermal overload on the reactor vessel wall and ensure the structural integrity of the reactor vessel wall.

Next, the fast breeder reactor of the present invention will be described with reference to an embodiment shown in FIG. 1), (3) is a low-temperature liquid metal, (4) and (5) are high-temperature liquid metals, and (6) is a cover gas space; One upper end protrudes from the liquid metal level into the cover gas space (6).

Next, the operation of the fast breeder reactor will be explained. When the thermal stratification phenomenon (Strat 2) occurs, as mentioned above, the low-density high-temperature liquid metal (4) on the upper side and the high-density low-temperature liquid metal (3) on the lower side are separated, as shown in Figure 2. stabilizes in the state of However, at this time, the liquid metal (5) between the inner cylinder (two inner cylinders and the reactor vessel wall (1)) remains at a high temperature, and the density difference between the inner cylinder (two inner cold liquid metal (3)) From the relationship (inner cylinder (
(Because the density of the low-temperature liquid metal (3) on the inside of the two is higher), the inner cylinder (low-temperature liquid metal (3) from the bottom of the two to the outside)
3) penetrates into the inner cylinder (the two outer hot liquid metals (5
) is pushed upward in a piston-like manner by the inner cylinder (two outer sides), and is about to be pushed out into the inner cylinder (two inner cylinders). 6), and the liquid level of the outer high temperature liquid metal (5) of the inner cylinder (2) is higher than that of the inner cylinder (2 inner liquid metal (3)).
(4), and due to the head difference (potential energy) corresponding to this height, the low temperature liquid metal (3) no longer flows from the bottom of the two to the outside, and the fourth
It stabilizes in the state shown in the figure. At this time, some of the low-temperature liquid metal (3) flows into the inner cylinder (the lower part of the two outer parts), but it is in areas that require thermal shock mitigation (such as the nozzle and welding parts).
Since it is far away, there is no particular problem.

The present invention provides a fast breeder reactor in which high-temperature liquid metal as a coolant flows from the bottom of the reactor vessel back up to the top of the reactor vessel. It has an inner cylinder that forms a buffer region, and the upper end of the inner cylinder protrudes from the liquid metal level into the cover gas space to perform the above-mentioned function. This has the effect of ensuring the structural integrity of the reactor vessel wall by preventing excessive heat from being applied to areas that require thermal shock mitigation.

In another embodiment, the inner cylinder (two upper ends protrude from the liquid metal level into the cover gas space (6), similar to the above). can achieve the following effects.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to these embodiments, and that various design changes can be made without departing from the spirit of the present invention. It is.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the reactor vessel and inner cylinder of a conventional fast breeder reactor, Fig. 2 is an enlarged vertical sectional side view of the arrow 1 part in Fig. 1, Fig. 6 is an explanatory diagram of its operation, Fig. 4 FIG. 5 is a longitudinal side view showing one embodiment of a reactor vessel and inner cylinder of a fast breeder reactor according to the present invention, and FIG. 5 is a longitudinal side view showing another embodiment. (1) Reactor vessel wall, (2) Inner cylinder, (3)
(4) (5)...Liquid metal, (6)...Cover gas space. Sub-agents: 3 patent attorneys and non-Kaihon important literary figures Figure 5

Claims (1)

[Claims] In a fast breeder reactor in which high-temperature liquid metal as a coolant flows from below the reactor vessel upward through the reactor core, an inner cylinder surrounds the upper part of the reactor core and forms a buffer region between it and the inner surface of the reactor vessel. A fast breeder reactor characterized in that the upper end of the inner cylinder protrudes from the surface of the entire liquid region into the cover gas space.