JPH0519677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] 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 with tritium-containing particles, for example, the first wall of the fusion reactor, usually has a wall body 1 made of stainless steel or the like, as shown in FIG. At the same time, a cooling water piping portion 2 is formed on the back side of the wall body 1, that is, at a portion located on the opposite side from the plasma side. That is, the structure is such that the cooling water flowing through the piping section 2 suppresses the rise in temperature of the wall body 1 due to heat from the plasma.

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 in the metal forming the wall body 1. 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 that permeates into the cooling water 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, the amount of tritium permeated into the cooling water was found to be several orders of magnitude larger than when using partial pressure differences. For this reason, in the conventional wall structure, the concentration of tritium in the cooling water increases, and there is a concern that the amount of tritium leaking into the environment due to leakage of the cooling water 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 cooling water. but,
Taking the case of a nuclear fusion reactor as an example, the amount of cooling water used in the first wall is expected to be around 1000m ³ , so it is quite difficult to set up equipment to process this large amount of cooling water.

[Purpose of the invention]

The present invention has been made in view of these circumstances, and its purpose is to provide a tritium permeation prevention wall device that can significantly suppress the amount of tritium permeated through the wall by simply adding simple equipment. It's about doing.

[Summary of the invention]

According to the present invention, the wall main body is configured to have a structure in which wall forming members are arranged in multiple layers of two or more and gaps are provided between the layers. A tritium removal system is connected to the gap in the wall body, which fills the gap with an inert gas and removes tritium from the inert gas.

〔Effect of the invention〕

With the above configuration, for example, if tritium accelerated particles are implanted into the wall body, the particles will diffuse within the wall body and, when they reach the gap described above, will destroy the undesired particles present in the gap. Enters active gas. For example, if the inert gas is currently circulating through the tritium removal device, the tritium that has entered the gap will be carried to the tritium removal device according to the flow of the inert gas and removed there. This results in a state of low tritium gas partial pressure. Therefore, the amount of tritium that passes through the wall body is not affected by the implantation and is simply proportional to this low tritium gas partial pressure, according to Siebert's law. Therefore, even if a piping section for cooling water is provided on the back side of the wall body, the amount of tritium penetrating into the cooling water can be extremely reduced. In this case, the amount of tritium that permeates through the wall body is reduced by removing the tritium gas mixed in the inert gas, and it is easy to remove tritium gas from the inert gas. Therefore, the initial objective can be achieved without incurring a high cost for the entire device. Furthermore, by using helium gas, which has good thermal conductivity, as the inert gas, the above-mentioned effects can be achieved without deteriorating the cooling characteristics.

[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 includes, for example, a first wall material 12 made of stainless steel, and a second wall material 12 made of stainless steel as well. and the wall material 13 of the first
The wall members 12 are located on the plasma side, and are arranged in a two-layer structure such that a gap 14 is formed between the first wall member 12 and the second wall member 13. Note that between the first wall material 12 and the second wall material 13, small diameter spacers (not shown) for maintaining the gap 14 are provided at multiple locations. Further, a flow path 15 is formed in the second wall material 13 to allow cooling water to flow therethrough.

Therefore, the gap 14 provided within the wall body 11
Both ends are connected to a tritium removal system 16, which will be described below. The tritium removal system 16 is located in the gap 14
It is formed in a closed loop configuration in which one open end of the gap 14 is connected to the other open end of the gap 14 via the piping 17, the tritium removal device 18, the piping 19, the pump 20, and the piping 21. It is filled with an active gas, such as helium gas. The tritium removal device 18 is specifically constructed as shown in FIG. That is, the container 22 is interposed in series between the piping 17 and the piping 19, and the first chamber 23 through which helium gas directly flows through the inside of the container 22 and the second chamber 23 through which helium gas does not flow directly.
A second chamber 24 is partitioned with a metal film 25 made of palladium or the like that allows tritium to pass therethrough, and a second chamber 2
4 is connected to a tritium trap 26. As the tritium trap 26, a container containing a metal tritium getter or a cryosorption panel is used.

With this configuration, when the pump 20 is operated, the helium gas sealed in the closed loop circulates through the gap 14. Since helium gas has excellent thermal conductivity, the heat of the first wall material 12 is efficiently transferred to the cooling water flowing through the flow path 15. Moreover, the heat of the second wall material 13 is also well transferred to the cooling water. Therefore, the wall body 11 will be cooled well.

Therefore, the surface of the first wall material 12 of the wall body 11 is exposed to tritium, deuterium, etc. from the plasma side.
Receives irradiation with particles such as neutrons. In this case, when accelerated tritium is present, a larger amount of tritium passes through the first wall material 12 and reaches the gap 14 than when it is not present. However, since helium gas is flowing in the gap 14, the tritium that has reached the gap 14 is quickly carried out outside the gap 14, and the tritium removal device 18
sent to. The tritium sent to the tritium removal device 18 passes through the metal membrane 25 while flowing through the container 22 and moves to the second chamber 24, and is then trapped in the tritium trap 26. Then, the helium gas from which tritium has been removed by the tritium removal device 18 is guided to the gap 14 again, and the helium gas is guided to the first wall material 12.
It is used to carry out the tritium that has passed through it.

In this way, even if the amount of tritium that permeates through the implantation is to be increased, once the infiltrated tritium reaches the gap 14, it is transferred to the outside of the wall body 11 and removed there. Therefore, even if accelerated tritium particles exist, the amount of tritium that actually permeates through the wall body 11 and the amount that permeates into the cooling water can be extremely reduced, and a sufficient tritium permeation prevention function can be achieved. In addition, even in the event that cooling water leaks, the deterioration of the environment can be kept to a minimum. Also,
Since the tritium removal system 16 is one that removes tritium from the gas, removal can be facilitated, and the above-mentioned functions can be achieved while simplifying the entire device. You can get something. In addition, since the gap 14 is provided between the first wall material 12 and the second wall material 13, even if the first wall material and the second wall material are made of different materials, the difference The stress caused by the difference in coefficient of linear expansion between the two members can be absorbed by the gap 14. Therefore, the second wall material provided with the flow path may be formed of a material having a lower tritium permeability than the first wall material.

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 18a having a cryosorption panel or a metal tritium getter directly disposed in the closed loop as shown in FIGS. 4 and 5 may be used. In addition, 31 in FIG. 4 is the tritium removal device 18a.
A heat exchanger is shown to eliminate the temperature difference at the inlet and outlet of the Also, as shown in Figure 6,
A tritium removal device 18b may be interposed between the pipes 17 and 19 to oxidize the tritium gas in the mixed gas in the oxidizer 32 and then remove it as tritium water in the tritium water absorber 33. Further, in each of the above-mentioned embodiments, the inert gas is circulated through the gap 14, but a system in which the tritium gas can be quickly transferred to the tritium removal device by diffusion even without circulation. As shown in FIG .
8, 18a. In this case, of course, inert gas is sealed in the pipes 34 and 35 and in the gap 14. Further, in the embodiment described above, a passage 15 for cooling the wall body 11 with cooling water is provided, but it goes without saying that the passage 15 may be omitted if cooling is not necessary. Furthermore, 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 configuration of a tritium removal device in the same device. The explanatory diagrams, FIGS. 4 to 6 are diagrams for explaining modified examples of the tritium removal device, respectively, and FIG. 7 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... Gap, 16 , 16 a
...Tritium removal system, 18, 18a, 18b...
...Tritium removal equipment.

Claims (1)

[Claims] 1 Arranging the wall forming members in a multilayer structure of two or more layers,
and a wall body having a gap between layers, and a tritium removal system connected to the gap of the wall body to fill the gap with an inert gas and remove tritium from the inert gas. A tritium permeation prevention wall device characterized by: