JPS6098397A - Gamma ray shielding material - 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 [Field of Application of the Invention] The present invention is applicable to high temperature and +t'! The present invention relates to a gamma ray shielding material suitable for high-speed nuclear reactors, particularly fast breeder reactor main cooling system shield ring bombs and tank-type fast breeders.

[Background of the invention]

The gamma ray shielding material used in the circulation pump of the main cooling system of conventional fast breeder reactors is a 1° steel ball and has a not particularly large specific gravity, so it is particularly effective in blocking gamma rays d1. Therefore, in order to obtain the required shielding effect, it is necessary to provide a γ-ray shielding layer having a certain length.

For this reason, the pump shaft length becomes long, so from the standpoint of pump reliability and miniaturization, there is a current demand for further shortening of the pump shaft length, that is, shortening the length of the gamma ray shielding layer. .

[Purpose of the invention]

In view of the above, the present invention can reduce the thickness of the γ-ray shielding layer when obtaining the same shielding effect as the conventional example,
Another object of the present invention is to provide a gamma ray shielding material that can provide an even higher shielding effect when the thickness of the shielding layer is the same, and can be used even at high temperatures without reducing thermal resistance. It is something.

[Summary of the invention]

In order to achieve the above object, the present invention has a γ-ray part made of a high melting point metal with a low specific gravity formed into a spherical shape, and a low melting point metal with a low specific gravity is housed in the spherical metal. [Embodiments of the Invention] Before explaining the embodiments of the present invention with reference to the drawings, we will explain the following main cooling system circulation pump (Fig. ) and tank-type fast breeder reactor (Figure 2).

First, in the circulation pump shown in FIG. 1, 1 is an outer casing having a suction port 2 and a discharge port 3 at the bottom, and a flow nozzle 4 at the top; 5 is provided at the bottom of the outer casing 1; A pump casing that communicates with the suction port 2 and the discharge port 3 has an impeller 6 inside the gauging 5.
is stored. 7 is a shaft directly connected to the impeller 5, and this shirt 1-7 is inside the outer gauging 1 and inside the inner casing 10 provided in the pump casing 5'' and the gamma ray shielding layer 12 provided on the inner casing 10. It is rotatably supported by a lower hydrostatic bearing 8 and an upper shaft seal 9.

1 is a plurality of heat shielding plates provided inside and outside a part of the inner casing 10.

In the circulation pump having the above structure, water is discharged from the discharge port 3 by the suction 6. At this time, a part of the sodium supplied to the hydrostatic bearing 8 flows between the outer casing 1 and the inner casing 10 and overflows from the overflow nozzle 4.

In addition, the sodium inside the outer casing 1 is at a high temperature (approximately 110
0 'C) and is radioactive, the upper part of the inner casing 10 is Since the heat shielding plate 11 and the γ-ray shielding layer 12 are provided, it is possible to suppress the upper part of the pump to a certain constant temperature (approximately 50° C.) and a non-hazardous radiation ff rate.

On the other hand, in the tank-type fast breeder reactor shown in Figure 2, 20
is a main container, and the inside of this main container 20 is divided by a partition wall 21 into a cold plenum 22 and a hot plenum 2:N. 24 is a roof slab that closes the upper portion 11 of the main container 20, and this roof slab 24 includes a monolithic shield ring bomb 25 inserted into the hot brenum 23 and the cold bream nano 122, and an intermediate heat exchanger. vessel 28
is installed and communicates with the circulation pump 25,
And in the furnace 1526 provided in the partition wall 21''-! /! A core upper mechanism 27 inserted into the hot plenum 23 is attached so as to cross over the core.

In the tank-type fast breeder reactor having the above structure, sodium in the cold plenum 22 is fed into the reactor core 26 by the main cooling system circulation pump 25 and carries thermal energy to the pot plenum 23. This thermal energy is transferred to the main vessel 2 by helium in the secondary system 1 in the intermediate heat exchanger 28.
0 is carried outside. In such a fast breeder reactor, the roof slab 24 serves as a heat and radiation shield.

Before;! i! @The gamma ray shielding layer 12 of the ring pump (Fig. 1) and the roof slab 24 of the fast breeder reactor (Fig. 2) are f
As shown in Figure J53, a high melting point metal 13a with a small specific gravity formed into a spherical shape and this high melting point metal! Gold bag C+311 with high specific gravity and low melting point stored in 311
The gamma ray shielding material 13 is made of a large number of γ-ray shielding materials 13, which are laminated in such a way that the rays are in contact with each other at the edges 14.

If the above-mentioned γ-ray shielding layer [2] is applied to the pump as shown in FIG. 1, the length of the pump shaft 7 can be shortened by 4 by shortening the γ-ray shielding Wj12.
The stiffness of the pump shaft 7 is increased by the increase in the rigidity of the pump shaft 7 and the fixed movement μl of the pump shaft 7.
It's easy. Increase the rotation speed again? Because it is possible to
We aim to downsize the pump, which has an extremely large diameter.
The cost of the entire plant] - can be reduced by l':, and this can be done twice.

On the other hand, if the roof slab 24 is applied to a high-speed T91 furnace as shown in W31, the roof slab 24)
By shortening , - main cooling system 11? j ring 7 doseop 25. The vertical length of the upper core mechanism 27, intermediate heat exchanger 28, etc. can be shortened. It will be possible to improve reliability by shortening the length of the bar and to reduce the overall cost of Plan 1 through the /I) type. A specific example of dmi will be explained with reference to FIGS. 4 to 6.

Fig. 4 shows the method of drawing foil by forging or pressing into a hollow hemispherical shape of 1.3 a + of high melting point metal with low specific gravity.

13a2, and both ff I :l fll, I
,',I After storing the sphere 13b made of a metal with a high specific gravity → low melting point in the 87, the hemispherical body 13a is
1 and 1382 are bonded to each other by diffusion bonding or explosive bonding.

The method shown in FIG.
After inserting the metal 4' at the reduction point 13r3 with a large specific gravity within 3Δ, the groin 30 is cut by rotating it by 90 degrees to make a non-spherical shielding material 13'.

Next, this shielding material 13' is formed into a spherical shielding material 13.

Furthermore, in the method shown in FIG. 6, the molten gold ff113'a with a low specific gravity and high melting point is allowed to flow like a waterfall, and into the metal 13'a in this flowing state, a spherical metal 13b with a ratio of 1F is poured.
By repeatedly cooling the spherical metal + 3 b to an extremely low temperature and passing it through the spherical metal + 3 b at a high speed, a film layer of the high melting point metal 13' a is formed on the surface of the spherical metal + 3 b.

〔Effect of the invention〕

- As explained above, according to the present invention, the spherical shape can be held by the outer high-melting point metal even at high temperatures, so it is possible to maintain point contact, thereby reducing the thermal resistance. However, the gamma ray shielding effect can be increased due to the high specific gravity of the metal inside.

[Brief explanation of drawings]

Figure 1 J3 and Figure 2 are longitudinal sectional views of the main cooling system 'JR'M pump and tank-type fast breeder reactor of a fast breeder reactor to which the embodiment of the gamma ray shielding material of the present invention is applied. The figure is the first
A cross-sectional view of the gamma ray shielding layer shown in the figure and the roof slab shown in Fig. 2,
FIGS. 4 to 6 are diagrams illustrating each manufacturing method of the γ-ray shielding material of the present invention. 13...7M shielding material, 13a...metal with low specific gravity and high melting point, 13b...gold JM with high specific gravity and low melting point. lI211 Zth brother 3 Figure 4 Figure closed 5 Figure 0 Rain 6 Figure

Claims (1)

[Claims] 1. A gamma ray shielding material made of a high melting point metal with a low specific gravity formed into a spherical shape, characterized in that a low melting point metal with a high specific gravity is housed within the spherical metal.