JPS6182193A - Automatic reactor stop aggregate - 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 [Technical Field of the Invention] The present invention provides an automatic reactor shutdown system that automatically and quickly detects 11 failures and scrams the core in order to prevent the spread of core accidents in fast breeder reactors. Ill do it to my body.

Technical Background of the Invention and Problem 1 Generally, in fast breeder reactors, the reactivity within the reactor core is controlled by inserting control rods into the reactor core. When an abnormality occurs in the reactor, these control rods are quickly inserted into the reactor core and a scram is performed.

However, when performing scram using such control rods, abnormal situations within the reactor core are detected and this detection 1
It is necessary to operate the control rod based on the g-bow. Therefore, if a detector or the like that detects an abnormality in the reactor core fails, there is a risk that a quick and reliable scram operation may not be performed.

[Object of the invention] The present invention has been made in response to such conventional circumstances,
It seeks to facilitate automatic reactor shutdown assembly by automatically and quickly detecting accidents and scramming the reactor.

[Summary of the Invention] In other words, the present invention provides a hollow guide tube having a cold lJI material inlet at the lower end and a coolant outlet at the upper end, and the cold IJI material inlet housed in the guide tube. a neutron absorber that falls downward as the flow rate of the coolant flowing in from the neutron absorber decreases, and an upper partition plate and a lower partition plate that are arranged in the guide tube and block the upward and downward movement of the neutron absorber, respectively. This is an automatic reactor shutdown assembly that is specially designed to be equipped with:

[Embodiment of the Invention] The details of the present invention will be described below with reference to an embodiment shown in the drawings.

Figures 1 and 2 show an automatic reactor shutdown assembly according to an embodiment of the present invention.
A hexagonal hollow guide tube is shown with a coolant inlet 2 and a coolant outlet 3 at its upper end.

This guide tube 1 accommodates an absorber capsule 5 that accommodates a large number of neutron absorbers 4 made of, for example, boron. This absorbent capsule 5 is placed on the upper part of the absorbent capsule 5.
An upper partition plate 6 is disposed to prevent upward movement of the absorbent capsule 5.
A lower partition plate 7 is disposed to prevent the movement of the frame in the F direction.

Therefore, the density of the absorber top cell 5 is such that when the flow rate of the coolant 8 flowing in from the cold JJI shrine inlet 2 is higher than a certain value, the upper end of the absorber dip cell 5 comes into contact with the upper partition plate 6; Absorber Kabu Pill 5 when it is lower than a certain value
The lower end of the lower end contacts the lower partition plate 7, which has a J-shaped density.

That is, as shown in curve a in Fig. 3, when the horizontal axis represents time and the vertical axis represents the coolant flow rate, the coolant flow m varies from WO at the rated time to We at the lowest flow rate at partial loading. During this period, the absorber capsule 5 contacts the upper partition plate 6, and between the time Tc and Tb when the coolant flow rate becomes equal to or less than WC, the absorber capsule 5 descends and contacts the lower partition plate 7. It is considered to be the density.

In the automatic reactor shutdown assembly configured as described above, as shown by curve a in Figure 3, due to some abnormal situation, the flow rate of the coolant made of liquid metal sodium, for example, gradually decreases, and the When the flow rate falls below the minimum flow rate WC, the absorbent capsule 5 falls downward and comes into contact with the lower partition plate 7, for example, several seconds to several tens of seconds after the time C.

As a result, the center of the absorber capsule 5 is located approximately at the center of the fuel section of the fast breeder reactor, and negative reactivity is applied within the reactor core. As a result, the reactor will automatically stop, making it possible to prevent a major accident that could lead to a core meltdown.

However, as mentioned above, in the automatic reactor shutdown assembly that has been completed (t1), due to the decrease in the coolant flow rate and the decrease in the core flow rate, the scram can be automatically and quickly performed without any external monitoring. 1゜Figure 4 J3 and 5
The figure shows another embodiment of the present invention, in which a fuel section 9 is arranged surrounding the guide tube 1.

The automatic furnace shutdown assembly of this embodiment has a guide tube 1 inserted into a wrapper tube 10 and has an Iζ shape. Between the guide tube 1 and the trumpet tray 10, there is a shaft plancher [・part 11,
A fuel section 12 is formed.

Further, in this embodiment, portions 13 are formed at the upper and lower portions of the absorber cover 5 to accommodate hem ram gas for adjusting the density of the bubble.

In the automatic reactor shutdown assembly configured as described above, during normal operation of the reactor, that is, when the core flow rate is above a certain value, the upper end of the absorber capsule 5 comes into contact with the upper partition plate 6,
The absorber cover L5 is located in the shaft blanket part 11.

On the other hand, when the core flow rate decreases to a constant value of 1, the absorber Cub Hill 5 descends as shown in FIG.
The central part is placed in an upright position J located at the central part of the fuel part 12. This allows the reactor to automatically shut down and prevent a major accident that could lead to a core meltdown.

7 and 8 show an embodiment of the automatic reactor shutdown assembly of the present invention suitable for a reactor core having an internal blanket section 14. In this embodiment, the absorber capsule 15 includes:
A capsule density adjusting section 17 having a cold fJ1 material inlet 16 through which a coolant flows is arranged in the center, and absorber sections 5 in which neutron absorbers 4 are accommodated are formed on both sides of the capsule density adjusting section 17 .

In the automatic reactor shutdown assembly constructed as described above, the absorber capsule 15 is located on the side of the shaft blanket 11, as shown in FIG. 7, during normal operation of the nuclear reactor.

On the other hand, when the core flow rate decreases, as shown in FIG. 8, the absorber capsule 15 falls and the capsule density adjustment section 17 is placed on the side of the internal blanket 14. This will automatically shut down the reactor and prevent a major accident that could lead to a core meltdown.

9 and 10 do not show yet another embodiment of the present invention, in which a fuel section 9 is disposed below the lower partition plate 7 of the guide tube 1.

Further, the absorbent capsule 18 has gas storage portions 19 formed above and below the absorbent capsule 18 for storing helium gas.

In the above-mentioned configuration, the automatic furnace is
During normal operation of the nuclear reactor, the absorber capsule 18 is placed on the side of the shaft blanket section 11.

On the other hand, when the core flow decreases, the lower end of the absorber capsule 18 comes into contact with the lower partition plate 7, as shown in FIG. 10, and absorbs the neutrons leaking upward from the fuel section 9 below. Furthermore, neutrons from the fuel section 12 shown in FIG. 9 are also absorbed. This will automatically shut down the reactor and prevent a major accident that could lead to a core meltdown.

[Effect of the invention] As described above, according to the automatic reactor shutdown assembly of the present invention,
Because the automatic reactor shutdown assembly itself has the ability to automatically and quickly detect a coolant flow rate reduction accident, it is possible to automatically shut down the reactor no matter what situation occurs, and the reactor core Major accidents that may lead to melting can be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an embodiment of the automatic reactor shutdown assembly of the present invention, FIG. 2 is a top view of FIG. 1, and FIG. 3 is a graph showing a decrease in core flow rate. 5 is a vertical cross-sectional view showing another embodiment of the automatic reactor shutdown assembly of the present invention, FIG. 5 is a top view of FIG. 4, and FIG. Longitudinal cross-sectional view showing the state of the body capsule, No. 7
The figure is a 11Jlvi plane view showing still another embodiment of the automatic reactor shutdown northeast 81 of the present invention, and FIG. 8 is the same as that in FIG. 7. FIG. 9 is a vertical cross-sectional view showing another embodiment of the automatic reactor shutdown assembly of the present invention, and FIG. FIG. 3 is a longitudinal cross-sectional view showing the state of the body capsule. 1...Guide pipe 2...Coolant inlet 3...
......Cold material 1 material outlet 4...
...Neutron absorber 5...Absorber cover 6...F section (C: Cutting plate 7...・・・・・・Lower partition plate 9・・・・・・
・・・・・・Fuel Dept. Agent, Bentoyama (11- Fig. 1 Fig. 3)

Claims (3)

[Claims] (1) A hollow guide tube with a coolant inlet at the lower end and a coolant outlet at the upper end; An automatic reactor shutdown assembly characterized by comprising a neutron absorber that falls into the guide tube, and an upper partition plate and a lower partition plate that are arranged in the guide tube and prevent upward and downward movement of the neutron absorber, respectively. . (2) The automatic reactor shutdown assembly according to claim 1, wherein the fuel section is arranged to surround the guide pipe. (3) The automatic reactor shutdown assembly according to claim 1, wherein the fuel section is disposed below the lower partition plate of the guide tube.