RU214875U1 - SEGMENT OF THE FIRST WALL OF THE THERMONUCLEAR REACTOR - Google Patents

Abstract

The utility model relates to thermonuclear technology, namely to the design of the first wall of a thermonuclear reactor or a thermonuclear neutron source that receives heat and neutron fluxes from plasma, and can be used in any device designed for isotope transmutation under the action of a neutron flux. The segment of the first wall consists of stiffeners, on which a steel base is fixed by welding, having longitudinal grooves in a semicircular shape, in which tubes of chromium-zirconium bronze are fixed by soldering. On top of the tubes, tiles are fixed by soldering, also having longitudinal grooves. The upper part of the steel base and the lower part of the tile contain transmutation material, forming transmutation zones I and II. The utility model enables transmutation of isotopes directly in the first wall of a thermonuclear reactor or a thermonuclear neutron source. 2 w.p. f-ly, 2 ill., 2 tab.

Description

Technical field

The utility model relates to thermonuclear technology, namely to the design of the first wall of a thermonuclear reactor or a thermonuclear neutron source that receives heat and neutron fluxes from plasma, and can be used in any device designed for isotope transmutation under the action of a neutron flux, in particular minor actinides and production of fissile fuel from the raw material.

State of the art

The first wall is one of the main components of a thermonuclear reactor or a thermonuclear neutron source and consists of several sections, and each section of the upper and lower segments, each with its own cooling system. Features of the operation of the first wall are:

- large thermal loads on its surface (average thermal load q _s ~0.25 MW/m ² , peak up to 1 MW/m ² );

- stationary mode of operation;

- the minimum thickness of the sections of the first wall due to the need for a minimum thickness of structural materials and water coolant to improve the neutron balance in the hybrid system.

The closest in technical essence to the claimed utility model is the design of the first wall segment, described in (A.Yu. Pashkov et al. "Thermo-hydraulic calculation and reliability assessment of water cooling systems of the first wall and the DEMO-TIN divertor." Issues of atomic science and Technology, series "Thermonuclear Fusion", 2018, vol. 41, issue 3, p. 36). The structural part of each segment of the first wall is a set of tubes made of chromium-zirconium bronze, through which the coolant is pumped. The bearing part of the structure, which perceives mechanical loads, is a base made of non-magnetic steel, in which semicircular grooves are made, in which tubes are installed. The tubes are soldered to the base with a layer of solder. In the lower part of the base there are transverse and longitudinal ribs that give rigidity to the structure. The wedge-shaped tiles are soldered to that part of each tube of the segment that does not come into contact with the base, which perceive the thermal load from the plasma. As the material of the tiles, Be or W are used, which are also breeders of neutrons. If a tile or part of it does not contain other materials than a neutron breeder, then it is called "clean".

During operation, the material of the tile is sprayed, but the remaining materials of the first wall are protected by tiles from spraying, while the heat flux from the plasma enters the surface of the tiles facing it. A stream of neutrons and gamma quanta also falls on it, which cause internal heat release in the material of the tiles. This thermal energy, as well as the energy incident on the surface of the tile, is removed by the coolant pumped through the tubes, and the temperature of the tiles is maintained at an acceptable level.

Tiles of the first wall have a limited service life for several reasons, among them:

- spraying material tiles;

- degradation of the properties of the material of tiles and structural materials of the first wall under the action of high-energy neutrons;

- cyclic thermal loads on the first wall.

Based on the totality of all factors, the service life of the first wall segments is estimated at 0.5-1 year, after which the first wall segments are removed from the fusion reactor and replaced with new ones. Because Since the materials of the first wall are highly activated and also contain tritium, the replacement of the first wall segments can only be carried out remotely.

The previously proposed designs of the first wall have a significant drawback, which is that the first wall is used only to receive the heat load from the plasma and protect materials from sputtering, and the transmutation process occurs in an independent structure - a blanket installed in the space between the first wall and the vacuum chamber. . A system is required for remote replacement of end-of-life segments of the first wall, while another system is required for blanket reloading, which complicates the design of a fusion reactor.

The technical problem to be solved by the claimed utility model is the simplification of the design of a thermonuclear reactor and the use of tiles both for receiving a thermal load from the plasma and protecting materials from sputtering, and for isotope transmutation. At the same time, the replacement of the segments of the first wall also provides an overload of the blanket.

Disclosure of the essence of the utility model

The technical result of the proposed utility model is the possibility of isotope transmutation directly in the first wall of a thermonuclear reactor or a thermonuclear neutron source.

To achieve a technical result, a segment of the first wall of a thermonuclear reactor is proposed, consisting of stiffeners, on which a steel base is fixed by welding, having longitudinal grooves of a semicircular cross section, in which tubes of chromium-zirconium bronze are fixed by soldering, and tiles also having longitudinal grooves are fixed on top of the tubes by soldering , while the upper part of the steel base and the lower part of the tile contain transmutation material, forming transmutation zones I and II.

In addition, transmutation zones I and II contain minor actinides Np, Am, Cm in the form of metals, alloys, or chemical compounds.

In addition, transmutation zones I and II contain raw material in the form of metals, alloys or chemical compounds Th-232, U-238 for the production of fissile fuel U-233, Pu-239.

Brief description of the drawings

In FIG. 1 shows a diagram of the first wall of a fusion reactor, and Fig. 2 its cross section with transmutation zones, where:

1 - tube made of chromium-zirconium bronze;

2 - tile;

3 - steel base;

4 - longitudinal stiffener;

5 - transverse stiffener;

6 - coolant (water);

7 - layer of solder (fixing the tile);

8 - layer of solder (tube fastening);

9 - transmutation zone I;

10 - transmutation zone II;

11 - plane separating the "clean" zone of the tile from the zone of transmutation I;

12 - "clean" part of the tile.

Implementation of the utility model

The essence of the utility model is illustrated by figures 1 and 2, which shows a diagram of the mutual arrangement of the elements of the first wall and its cross section.

The structural part of each segment of the first wall is a set of tubes 1 made of chromium-zirconium bronze, through which the coolant 6 is pumped. a layer of solder 8. Transverse 5 and longitudinal 4 ribs are welded to the lower part of the steel base 3, which give strength to the structure. Tiles 2 are soldered to the upper part of each tube 1 with a layer of solder 7, which perceive the thermal load from the plasma. As the material of tiles 2, Be or W are used, which are also neutron breeders.

If tile 2 or part of it does not contain other materials than the neutron breeder, then it is called "clean".

Tile 2 has a transmutation zone 19 below a plane 11 drawn parallel to the plasma surface of the tile, which occupies approximately one third of the total volume of tile 2 in volume. It contains either minor actinides or raw material.

The “clean” part of tile 12, which does not contain minor actinides or raw material, is located above plane 11. It can be sputtered during the operation of a thermonuclear reactor, and if minor actinides or raw material are present there, they will enter the plasma of the discharge chamber, which is undesirable.

The transmutation zone II 10 is located in the upper part of the steel base 3 and occupies only a part of it, which is necessary to maintain the strength of the base. It also contains minor actinides or raw material.

The following combinations of materials are possible in transmutation zones:

- Only transmutation zone 19 with minor actinides or raw material is installed;

- Only transmutation zone II 10 with minor actinides or raw material is installed;

- Both transmutation zones are installed in the following combinations:

- transmutation zone I 9 - minor actinides, transmutation zone II 10 - minor actinides;

- transmutation zone I 9 - minor actinides, transmutation zone II 10 - raw material;

- transmutation zone I 9 - raw material, transmutation zone II 10 - raw material;

- transmutation zone I 9 - raw material, transmutation zone II 10 - minor actinides.

Minor actinides or raw material in transmutation zones can be used as follows:

- in the form of metals and form an alloy with the material of tile 2 and steel base 3;

- form chemical compounds with the material of tile 2 or steel base 3;

- in the form of particles from chemical compounds (oxides, nitrides, carbides, etc.) dispersed in the material of tile 2 or steel base 3.

Minor actinides (Np, Am, Cm) are used in the form of metals, alloys or chemical compounds for transmutation, or raw materials (metals, alloys or chemical compounds Th-232, U-238) for the production of fissile fuel (U-233, Pu- 239).

When the service life of the first wall segment expires, the fusion reactor is shut down and the first wall segments are remotely removed from it. Tiles 2 are separated from tubes 1 and sent for processing, where either minor actinide residues or accumulated fissile fuel are separated from them. The steel base 3 is also recycled.

Examples of specific implementation, which do not limit the options for their implementation.

The claimed design of the first wall segment is installed in the DEMO-TIN thermonuclear facility. Assumptions accepted.

The transmutation zone I 9 is located only in tiles 2 and contains minor actinides in the form of a mixture of Np, Am, and Cm oxide particles dispersed in metallic Be. The density of the mixture of oxides - r _MA =9000 kg/m ³ . The isotopic composition of minor actinides is given in Table 1.

The total number of neutrons in the spectrum of the DEMO-FIN facility (total neutron flux) is 1.42⋅10 ¹⁹ n/s, which corresponds to a thermonuclear power of 40 MW.

The process of transmutation of minor actinides under the action of a neutron flux occurs as follows. Neutrons from plasma and Be or W nuclei enter the nuclei of minor actinide atoms and split them. In this case, fission products arise - isotopes with a shorter half-life and less toxic.

The main dimensions of the tile are shown in Fig. 2. The length of one tile is 0.1 m.

S _pov - surface area of the tile - 1.7⋅10 ^-3 m ² ;

S _PS - surface area of the first wall ~160 m ² ;

N - number of tiles in the first wall ~ Snc/SnoB=94100;

V _t1 - the volume of one tile - 7.97⋅10 ^-6 m ³ ;

V _tr1 ~V _t /3 - the volume of the transmutation zone I in a tile - 2.66⋅10 ^-6 m ³ ;

V _tr =V _trp1 N - total volume of the transmutation zone I in the first wall -0.25 m ³ ;

x is the volume fraction of oxides of minor actinides in the transmutation zone;

V _MA =V _{tp ⋅x} is the volume of oxides of minor actinides in the first wall;

М _МА =r _MA ⋅V _MA is the mass of oxides of minor actinides in the first wall.

Estimates of the amount of oxides of minor actinides in the transmutation zone I are given in Table 2.

If transmutation zones I and II are used, the amount of minor actinides in the first wall will double.

The transmutation of minor actinides was calculated by the Monte Carlo method using the MCNP-4 program with cross sections from the FENDL-2 ENDF/B-6 files.

For x=0.02 and M _MA =45 kg, the amount of minor actinides subjected to transmutation was 4.55 kg per year, i.e. ~10% of the original amount.

Thus, the main advantages of the proposed design are:

1. The ability to transmute elements without the use of a blanket and related elements (fastening, cooling, overloading, safety systems).

2. Ability to perform reloading by replacing the elements of the first wall, which will be regularly performed in a thermonuclear reactor even when using only "clean" tiles.

3. Possibility to make full use of neutrons from plasma and breeder for transmutation of elements.

4. Simplicity of tile design.

5. Possibility to implement both the transmutation of minor actinides and the production of fissile fuel in the first wall.

Claims (3)

1. Segment of the first wall of a thermonuclear reactor, consisting of stiffeners, on which a steel base is fixed by welding, having longitudinal grooves of a semicircular cross section, in which tubes of chromium-zirconium bronze are fixed by soldering, and tiles, also having longitudinal grooves, are fixed on top of the tubes by soldering, characterized in that that the upper part of the steel base and the lower part of the tile contain transmutation material, forming transmutation zones I and II. 2. Segment according to claim 1, characterized in that transmutation zones I and II contain minor actinides Np, Am, Cm in the form of metals, alloys or chemical compounds. 3. Segment according to claim 1, characterized in that transmutation zones I and II contain raw material in the form of metals, alloys or chemical compounds Th-232, U-238 for the production of fissile fuel U-233, Pu-239.

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