JPH0695157B2 - Tritium production equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses a solid lithium compound such as lithium oxide to produce tritium for use in a nuclear fusion reactor, a nuclear fission reactor, or a test device for these, etc. For tritium production equipment for.

[Technical background] Tritium, which is a fuel for a fusion reactor, is produced by the reaction of lithium and neutrons. ⁶ Li for natural lithium
7.4% ⁷ Li is 92.6%, but to generate a tritium together react with neutrons, ⁶ Li If and nuclear producing tritium using nuclear fission reactor because it is easy to generate a tritium when neutron energy is low Neutron multiplication in the fusion reactor
It is mainly used in tritium production, such as when producing tritium using a blanket with a moderator installed on the plasma side, and is of high importance. FIG. 4 shows a schematic diagram of an apparatus for producing tritium using a conventional nuclear fission reactor. 41 in the figure
Is a tritium production device, and 42 is a nuclear fission reactor. The tritium production apparatus 41 is provided with a lithium container 44 filled with a breeding material made of lithium compounds such as lithium oxide (Li ₂ O) in the form of fine pebbles. The container 44 is inserted into the position of the core 43, and neutrons are irradiated to generate tritium. The generated tritium is diffused in the purge gas such as helium sent through the sweep gas supply pipe 45, and is recovered by the tritium recovery device 47 through the sweep gas discharge pipe 46. As shown in FIG. 5, the container 44 has a cooling water pipe 53 penetrating therethrough, and removes heat generated during the tritium generation reaction. In FIG. 5, 52 is a lithium compound pebble and 54 is a spacer tube.

6 and 7 are explanatory views of an apparatus for producing tritium using a conventionally proposed fusion reactor, FIG. 6 is a schematic sectional view of the fusion reactor, and FIG. 7 is tritium breeding. It is a fragmentary sectional view of a blanket. In the fusion reactor 61, a tritium breeding blanket 63 arranged around the plasma 62.
To produce tritium. The tritium breeding blanket 63 has a neutron multiplier / moderator 65 inside the outer wall 64, and a pebble made of a fine-grained lithium compound inside.
It has a composite structure containing a lithium container 69 filled with 68. Neutrons incident from the plasma 62 side are decelerated by the neutron multiplication / moderation material 65 and react with ⁶ Li in the pebbles 68 to generate tritium. The generated tritium is pebbles
It is recovered by the helium purge gas flowing around 68. A cooling pipe 67 penetrates through the lithium container 69 and absorbs heat generated during the tritium generation reaction to cool the lithium container 69.

[Problems of the prior art] When trying to generate tritium by the reaction between ⁶ Li and thermal neutrons as described above, there is a problem that the reaction mainly occurs in the vicinity of the surface on which the neutron is incident. . As shown in FIG. 5, when the container 44 is filled with the pebble 52 and irradiated with thermal neutrons from the surroundings, a very high tritium production rate and a high heat generation rate are exhibited in the vicinity of the surface on which thermal neutrons are incident. At the same time, a rapid decay occurs, and the tritium production rate and heat generation rate are extremely low near the center of the figure. For example, when a small spherical pebble of lithium oxide (Li ₂ O) using natural lithium is filled in a container at a filling rate of 60% and irradiated with thermal neutrons, thermal neutrons are one digit at a depth of 10 mm from the incident surface. It will be attenuated more. Such a phenomenon similarly occurs in the tritium breeding blanket in FIG. 7, and there is a problem that the tritium production reaction and heat generation are concentrated near the surface in the neutron incident direction indicated by the arrow.

In the tritium production reaction, the pebbles made of a lithium compound undergo a chemical reaction when the temperature becomes too high and the quality is altered.If the temperature is too low, the generated tritium does not diffuse into the purge gas and it becomes difficult to recover it.
It is necessary to keep in the range of ℃ ~ 1000 ℃, but if the reaction is biased near the incident surface of neutrons as described above, it becomes difficult to remove heat near the incident surface and the entire pebble is kept at a constant temperature. It becomes difficult to control.

In addition, there were many problems such that the reaction of only ⁶ Li near the incident surface proceeded and the interior with a low reaction rate was effectively wasted.

For such problems, ⁶ L near the neutron incident surface
lowering the atomic number density of i, an attempt to achieve flattening of tritium production rate and heat generation rate in the lithium filling container by raising the atomic number density of ⁶ Li inside, in the vicinity of neutrons incident surface ⁶ Li It has been proposed to place a depleted solid lithium compound and a lithium compound enriched with ⁶ Li inside. However, in this method the concentration step of the impairment process and ⁶ Li of ⁶ Li is essential, there is also a drawback in terms of time-consuming after expenses can not be used lithium present naturally.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tritium production apparatus that provides a flat tritium production rate and a heat generation rate distribution by using an ordinary lithium compound with a simple configuration. .

[Means for Solving Problems] The above object is achieved by the tritium production apparatus described in the claims. That is, the mixing ratio of the lithium compound fine granular molded body and the lithium compound-free fine granular molded body, the content of the lithium compound increases as it goes from the neutron incident surface side of the pebble layer to the deep part of the pebble layer. It is a tritium production device arranged like this.

In the present invention, the pebble for producing tritium is arranged at least on the neutron incident surface side by adjusting the number of atoms of ⁶ Li by appropriately mixing those made of a lithium compound and those not containing a lithium compound, and at a deeper portion. To use the same pebbles as the neutron incident surface, or only the lithium compound fine granular molded body, or change the mixing ratio of the lithium compound fine granular molded body and the lithium compound-free fine granular molded body Therefore, a pebble with an increased number of ⁶ Li atoms is arranged as compared with the pebble for producing tritium arranged on the neutron incident surface side.

[Examples] FIG. 1 is an explanatory view showing the concept of a pebble used in the tritium production apparatus of the present invention, in which 1 is a finely-divided molded product made of a lithium compound and having a diameter of about 1 mm, 2 is a diameter not containing a lithium compound It is a fine granular molded body of about 1 millimeter. Li ₂ O, LiAlO ₂ , Li ₂ SiO ₃ etc. as lithium compounds, SiO ₂ , Al ₂ as fine particles not containing lithium compounds
O ₃ , aluminum (Al), etc. are selected. Fig. 1 (a)
Shows a state in which the fine particles 1 of the lithium compound and the fine particles 2 not containing the lithium compound are mixed, and FIG. 6 (b) shows the mixture ratios thereof being different. In this way, the amount (content ratio) of the lithium compound in the tritium-producing pebble can be arbitrarily adjusted by changing the mixing ratio of the two.

FIG. 2 is a partially cutaway perspective view of an embodiment of the tritium production apparatus of the present invention, which is for a nuclear fission reactor. 3 is a tritium production device, 4 is a lithium storage container, 5 and 6 are pebble layers composed of a mixture of a lithium compound fine granular molded body 1 and a lithium compound-free fine granular molded body 2, and 7 is a lithium compound molded body. It is a pebble layer consisting of only. 5 is a pebble layer containing the smallest amount of lithium compound particles, 6 is a pebble layer containing a larger amount of lithium compound particles than the above pebble layer 5, and 7 is a pebble layer containing the largest amount of lithium compound. Becomes

Each fine granular molded body of the pebble layer consisting of a mixture of a fine granular molded body of the above lithium compound and a fine granular molded body not containing a lithium compound is preliminarily sintered as a simple substance powder under high temperature conditions, and formed into a fine granular state. It was formed. Therefore, for example, even if a sintered Li ₂ O molded body and a sintered SiO ₂ molded body are mixed and filled in the pebble layer portion of the tritium production apparatus, new sintering does not occur and Li ₂ SiO _There is no chemical change to ₃ . Further, the pebble layer portion mixed and filled has a cooling water pipe (original specification No. 2) separately installed so that a new sintering reaction does not occur.
Reference numeral 10, reference numeral 34, and reference numeral 53 in FIG. ) To remove the heat and keep it at a predetermined temperature.

The lithium-compound-made fine granules and the lithium-compound-free fine granules are a mixture of these and are granular. When filling this mixture into each pebble layer, the required number and shape of pebble layers are formed by the lithium storage container 4 which has been processed into a desired shape in advance and a pebble layer partition plate (not shown), and thereby the pebble layers are divided. The "lithium compound-made fine granular molded body" and the "lithium compound-free fine granular molded body", which are mixed at a predetermined ratio, are mixed and filled in each of the formed layers. This allows the mixture to retain its shape as a layer. After the mixture is filled, the pebble layer partition plates and the like arranged at the boundaries of the above pebble layers are removed. It is also possible to leave it.

When the tritium production apparatus configured as described above is inserted into the core part of a nuclear fission reactor and helium gas is sent out from the sweep gas supply pipe 8, the helium gas permeates into the pebble layers 5, 6, 7 from the lower portion of the lithium storage container. Neutrons from the nuclear fission reactor enter the lithium containment vessel from the outer peripheral direction, but the outermost pebble layer 5 has a low lithium compound content of ⁶ L.
Since the number of atoms of i is small and the content of lithium compound increases in order to reach the inner layers 6 and 7, the number of atoms of ⁶ Li increases, the tritium production reaction should be concentrated only in the outermost layer. Nonetheless, a flattened reaction occurs also in the pebble layers inside 6,7. The generated tritium diffuses in the helium gas and is collected by the tritium recovery device (not shown) through the sweep gas discharge pipe 9. The heat generated in each pebble layer is flattened in each layer and is not concentrated in the outermost layer, so that the cooling water pipe 10 effectively removes heat.

FIG. 3 is another embodiment of the present invention and is a partially cutaway perspective view showing an example of a tritium production blanket used in a nuclear fusion reactor. FIG. 31 is a tritium breeding blanket, 32 is an outer wall, 33 is a neutron multiplier / moderator (Be), 34 is a cooling water pipe,
35 is a pebble layer containing the smallest amount of lithium compound particles, and 36 is a pebble layer containing the smallest amount of lithium compound particles.
A pebble layer containing more than 35, 37 is a pebble layer containing the largest amount of a lithium compound, or a pebble layer containing only fine particles of a lithium compound. The white arrow indicates the incident direction of neutrons, the layer having a small lithium compound content is arranged on the surface side in the incident direction, and the layer having a large lithium compound content is arranged on the deep side.

Therefore, similar to the above, the tritium formation reaction does not concentrate only on the outermost pebble layer on the neutron incident surface side, but on the pebble layers
The entire surface of the pebble layer is flattened 6,6, and the reaction does not occur effectively in the entire pebble layer, resulting in no waste in the deep portion. Since the heat generation is not concentrated on the neutron incident surface side, heat is effectively removed by the cooling water pipe 34, and it is not necessary to arrange a large number of cooling water pipes on the incident surface side, and the structure is simple.

In the above embodiment, an example in which the pebble layer is three layers is shown, but
If necessary, the reaction rate can be flattened by using two layers or more layers, and the tritium production reaction can be performed by filling the pebble with the adjusted ⁶ Li atom number evenly without using the multilayer. It is possible to reduce the concentration in the vicinity of the incident surface.

[Effect of the Invention] According to the present invention, ⁶ L can be obtained by using an ordinary lithium compound without requiring special steps such as concentration and depletion of ⁶ Li.
It is possible to use a tritium generation pebble with the number of i atoms adjusted, which effectively prevents the concentration of the tritium generation reaction near the neutron incident surface, and makes it possible to efficiently use the filled lithium compound internally. However, there are many advantages such as flattening the heat generation rate distribution and facilitating heat removal.

[Brief description of drawings]

FIG. 1 is an explanatory view of an example of a tritium production pebble used in the practice of the present invention in both (a) and (b), and FIG. 2 is a partially cutaway perspective view of a tritium production apparatus for a nuclear fission reactor in the embodiment of the present invention. FIG. 3 is another embodiment of the present invention, a partially cutaway perspective view of a tritium breeding blanket for a fusion reactor, FIG. 4 is a schematic sectional view of a conventional tritium production apparatus for a nuclear fission reactor, and FIG. 6 is a cutaway perspective view of the tritium production apparatus of FIG.
FIG. 7 is a schematic sectional view showing a conventional tritium production apparatus using a fusion reactor, and FIG. 7 is a partially cutaway perspective view of the tritium breeding blanket shown in FIG. 1 ... fine granular product made of lithium compound, 2 ... fine granular product not containing lithium compound, 3 ... tritium production device, 4 ... lithium container, 5,6,7 ... pebble layer, 31 ...... Tritium breeding blanket, 35,36,37 ……
Pebble layer

Claims (1)

[Claims] 1. A lithium compound content ratio of a lithium compound fine-particle compact and a lithium-compound-free fine granule compact as the mixture ratio goes from the neutron incident surface side of the pebble layer to the deep part of the pebble layer. The tritium production device is characterized by being arranged so that