JPH0519678B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Technical Field] The present invention relates to a tritium permeation prevention wall device suitable for a partition wall provided in a place that is irradiated with tritium accelerated particles.

[Background technology of the invention and its problems]

A wall whose surface is irradiated by energetic particles containing tritium, for example a first wall for isolating the plasma region of a fusion reactor from the external environment, is usually constructed as shown in FIG. , while forming the wall body 1 from stainless steel or the like,
A cooling liquid piping portion 2 is formed on the back side of the wall body 1, that is, on the opposite side from the plasma side. In other words, the temperature of the wall body 1 increases due to the irradiation of energetic particles.
It has a structure in which the cooling liquid flowing through the piping section 2 suppresses this.

However, it has been found that the wall structure described above has the following problems. That is, the surface of the wall body 1 located on the plasma side is irradiated with tritium T, deuterium D, neutrons n, and other particles. Among these, tritium has properties as a hydrogen isotope, so it is proportional to the 1/2 power difference in the partial pressure of tritium on both surfaces of the metal according to Siebert's law. and pass through. In the case of a fusion reactor, the tritium gas partial pressure on the plasma side is
10 ^-4 Torr, and therefore the amount of tritium penetrating into the coolant based on the partial pressure difference is very small. However, accelerated tritium particles exist on the plasma side, and if we take into account the implantation phenomenon in which these tritium accelerated particles are implanted into the first wall surface, it is possible that tritium will penetrate into the coolant. It has been found that the amount is several orders of magnitude higher than when using partial pressure differences. For this reason, in the conventional wall structure, the concentration of tritium in the coolant increases, and there is a concern that the amount of tritium leaking into the environment due to leakage of the coolant increases. Moreover, it is not preferable from the viewpoint of tritium economy.

Therefore, in order to eliminate such problems,
It is conceivable to provide a tritium removal system to recover tritium that has permeated into the coolant. but,
Taking the case of a nuclear fusion reactor as an example, the amount of coolant used in the first wall is expected to be around 1000 m ³ , so it is quite difficult to set up equipment to handle this large amount of coolant. In addition, as another means, on the surface of the wall body 1 that is irradiated with energetic particles,
It has also been proposed to provide a so-called trichiuchi barrier with multiple layers of oxide film and ceramic layers, but since different materials are used, it is difficult to absorb the stress applied to the joint surface due to the difference in coefficient of thermal expansion. There are problems with technical impracticality.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and aims to reduce the amount of tritium that can pass through the wall body without reducing the mechanical strength and cooling properties of the wall body, and to reduce the amount of tritium that can pass through the wall body without reducing the mechanical strength and cooling characteristics of the wall body. To provide a tritium permeation prevention wall device which can suppress the amount of tritium permeation into a cooling liquid for cooling a main body to a sufficiently small value and is easy to manufacture.

[Summary of the invention]

According to the present invention, channel-like cavities are provided at predetermined pitches in the wall body at positions between the surface that is irradiated with energetic particles and the coolant passage formed in the wall body. A tritium removal system is provided to remove tritium gas that has permeated into the cavity.

〔Effect of the invention〕

As described above, a cavity in the form of a predetermined pitch channel exists between the surface that is irradiated with energetic particles and the coolant passage. For example, if the cavity is filled with an inert gas and connected to the tritium removal system, the heat generated on the side of the wall that is irradiated with energetic particles will mainly be It is conducted between the cavities and transmitted to the coolant passage, and is taken away by the coolant flowing through the coolant passage. It is therefore possible to increase the inert gas pressure in the cavity and to cool the wall body well without the aid of heat conduction via this inert gas. Furthermore, since the cavities are provided in the form of channels with a predetermined pitch, there is no risk of lowering the mechanical strength of the wall body as much as in the case where the cavities are provided in the form of gaps. In addition, when tritium accelerated particles are implanted into the wall body, the particles advance within the wall body by diffusion, but in this case, the space between the cavities is kept at a lower temperature than the inside of the cavity. , most of the advanced tritium penetrates into the cavity,
It is then removed by a tritium removal system.
Therefore, the amount of tritium that permeates into the coolant can be suppressed to such an extent that it hardly becomes a problem.
As described above, according to the present invention, it is possible to suppress the amount of tritium that permeates through the wall body and the amount of tritium that permeates into the cooling liquid to a very small value without reducing the cooling characteristics and mechanical strength of the wall body. can.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. Note that this embodiment is an example in which the present invention is applied to the first wall of a nuclear fusion reactor.

In FIG. 2, reference numeral 11 is a wall body constituting the first wall of the fusion reactor, and this wall body 11 is
For example, a first wall material 12 made of stainless steel and a second wall material 13 made of copper, which has excellent thermal conductivity and low tritium permeability, are arranged such that the first wall material 12 is located on the plasma side. It is arranged in a two-layer structure.

Coolant passages 14 are formed in the second wall material 13 at a predetermined pitch so as to be parallel to the first wall material 12.
Both ends are connected to a coolant circulation system (not shown). Further, the first wall material 12 of the second wall material 13
As shown in FIG. 3, grooves 15 perpendicular to the coolant passage 14 are formed at a predetermined pitch on the contact surface with the cooling liquid passage 14. The material 12 forms a channel-shaped cavity 16 within the wall body 11 .

Thus, the cavity 16 provided within the wall body 11
Both ends are connected to a tritium removal system 17, which will be described below. The tritium removal system 17 is located in the cavity 16
It is formed in a closed loop configuration in which one open end of the cavity 16 is connected to the other open end of the cavity 16 via the piping 18, the tritium removal device 19, the piping 20, the pump 21, and the piping 22. It is filled with an active gas, such as helium gas. The tritium removal device 19 is specifically constructed as shown in FIG. That is, the container 23 is interposed in series between the piping 18 and the piping 20, and the first chamber 24 through which helium gas directly flows through the inside of the container 23 and the second chamber 24 which does not communicate with the inside of the container 23.
A second chamber 25 is partitioned with a metal film 26 made of palladium or the like that allows tritium to pass through.
5 is connected to a tritium trap 27. As the tritium trap 27, a container containing a metal tritium getter or a cryosorption panel is used.

With such a configuration, when the coolant circulation system is operated, the coolant flows through the coolant passage 14, and when the pump 21 is operated, the helium gas sealed in the closed loop flows through the cavity 16. and circulate.

The surface of the first wall material 12 of the wall body 11 is irradiated with energetic particles such as tritium, deuterium, and neutrons from the plasma side, so that it generates heat. This heat is conducted inside the first wall material 12 and then the fourth wall material 12.
As shown in the figure, the heat is mainly conducted through the portion X located between the cavities 16 in the second wall material 13 and is transmitted to the coolant flowing through the coolant passage 14 . Therefore, the wall body 11 is cooled well. Note that by increasing the pressure of the helium gas flowing through the cavity 16, good heat conduction can be achieved through this helium gas.
6 are provided at a predetermined pitch, there are a large number of portions X, and therefore good cooling can be achieved without particularly increasing the pressure inside the cavity 16.

Therefore, as described above, the first wall material 12 is irradiated with energetic particles containing tritium.
In this case, when accelerated tritium exists, a larger amount of tritium permeates through the first wall material 12 than when it does not exist, but most of the permeated tritium gas is due to the following reason. It penetrates into the cavity 16. That is, the amount of permeation of tritium is proportional to the diffusion coefficient D. On the other hand, the diffusion coefficient D depends on the temperature, and increases as the temperature increases, as shown in equation (1) below.

D=D ₀ exp (−Q/RT) (1) where D ₀ is a constant, Q is activation energy, R is a gas constant, and T is temperature K.

Here, in the wall body 11 of the tritium permeation prevention wall device according to the present invention, a cavity 16 through which an inert gas flows exists at a position between the first wall material 12 and the cooling liquid passage 14. Inside the cavity 16,
The thermal conductivity between the cavities 16 and the portion X of the material located between the cavities 16 is much greater in the portion X. For this reason, in the area A and the area B shown in Figure 4, the temperature of the area A is higher, and therefore the diffusion coefficient D of the area A is larger than that of the area B. . Therefore, the amount of tritium that passes through the A portion is much greater than that which passes through the B portion. In other words, most of the tritium migrates into the cavity 16, and the amount that permeates through the portion B and permeates into the coolant is so small that it can be ignored.

Since helium gas is flowing through the cavity 16, the tritium that has reached the cavity 16 is quickly carried out to the cavity 16 and sent to the tritium removal device 19. The tritium sent to the tritium removal device 19 is transferred to the container 23.
While flowing through the interior, it passes through the metal membrane 26 and moves to the second chamber 25, after which it is trapped in the tritium trap 27. The tritium-free helium gas that has exited the tritium removal device 19 is guided to the cavity 16 again and is used as a carrier of tritium that has passed through the first wall material 12. Therefore, the amount of tritium that permeates through the wall body 11 and the amount of tritium that permeates into the coolant can be greatly reduced.
In other words, the amount can be reduced to a negligible amount, and the function as a tritium permeation prevention wall device can be effectively exhibited. Furthermore, since the cavities 16 are provided at a predetermined pitch, the wall main body 11 can exhibit sufficient mechanical strength, unlike, for example, a structure in which the cavities 16 are replaced with gaps. is obtained.

Note that the present invention is not limited to the embodiments described above. For example, in the embodiment described above, two or more systems of tritium traps may be provided in parallel, and tritium may be continuously recovered by sequentially switching and using these traps. Alternatively, the piping for guiding the inert gas may have a double pipe structure, the inert gas may be passed between the inner pipe and the outer pipe, and tritium may be recovered from this inert gas as well. . Further, as the tritium removal device, a tritium removal device 19a having a cryosorption panel or a metal tritium getter directly disposed in the closed loop as shown in FIGS. 6 and 7 may be used. In addition, 31 in FIG. 6 is the tritium removal device 19a.
A heat exchanger is shown to eliminate the temperature difference at the inlet and outlet of the Also, as shown in Figure 8,
A tritium removal device 19b may be interposed between the pipes 18 and 20, which oxidizes the tritium gas in the mixed gas in the oxidizer 32 and then removes it as tritium water in the tritium water absorber 33. . Further, in each of the above-described embodiments, the inert gas is circulated through the cavity 16, but there is a system in which the tritium gas can be quickly transferred to the tritium removal device by diffusion even without circulation. In this case, as shown in FIG. 9, the openings at both ends of the cavity 16 provided in the wall body 11 may be connected to tritium removal devices 19 and 19a via pipes 34 and 35. In this case, of course, the inside of the pipes 34 and 35 and the cavity 16
Inert gas is sealed inside. Moreover, it goes without saying that the wall forming member is not limited to two layers.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining a conventional wall structure, FIG. 2 is an explanatory diagram of the configuration of a tritium permeation prevention wall device according to an embodiment of the present invention, and FIG. 3 is a line taken along line E-E in FIG. 2. 4 is a partially enlarged view thereof, FIG. 5 is an explanatory diagram of the configuration of the tritium removal device in the same device, and FIGS. 6 to 8 are diagrams for explaining modified examples of the tritium removal device, respectively. ,
FIG. 9 is an explanatory diagram of the configuration of a tritium permeation prevention wall device according to another embodiment of the present invention. 11 ...Wall body, 14...Cooling liquid passage, 16...
...Cavity, 17 , 17a ...Tritium removal system, 1
9, 19a, 19b...tritium removal device.

Claims (1)

[Claims] 1. A wall body with a single or multilayer structure provided to partition an atmosphere in which energetic particles containing tritium exist and an atmosphere not containing tritium, and a wall body provided at a predetermined pitch on the side of the atmosphere not containing tritium within this wall body. a channel-like cavity provided at a predetermined pitch between a surface receiving the energy particle irradiation and the cooling fluid passage within the wall body; A tritium permeation prevention wall device comprising a tritium removal system for removing tritium gas that has entered a cavity.