JPH0442321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for collecting, storing and supplying tritium gas.

(Prior Art) Conventionally, a so-called uranium bed, in which active uranium metal is sealed in a container, has been widely used for the collection, storage, and supply of a mixed gas of hydrogen isotopes containing tritium (hereinafter simply referred to as tritium gas). Ta.
However, uranium metal is a nuclear fuel material;
Its acquisition, processing, and use are legally regulated and restricted, making it extremely inconvenient in practice. Furthermore, since uranium and its hydride powder are chemically active and have the property of igniting in the air, handling them requires an inert gas atmosphere, which poses a high risk in the event of an accident. Furthermore, due to its sinterability and eutectic properties with other metals, it is necessary to pay attention to heat generation due to hydrogenation and temperature control during heating, making it difficult to handle.

To avoid the above drawbacks of uranium metal, Ti,
Metals and alloys such as Zr, Y, and ZrAl have been tried for similar purposes. However, all of these materials have low equilibrium decomposition pressures for hydrides, and while they are useful for tritium recovery at room temperature, as shown in Figure 1, they are not suitable for supplying tritium gas that needs to be released at approximately 1 atm. Requires high temperature of 800℃ or more,
It is not suitable as a material for equipment that uses tritium, which is said to be desirably below 500°C in terms of stability, especially tritium permeation. Recently, intermetallic compounds
The use of ZrNi has also been attempted, but the trihydride has a high equilibrium decomposition pressure and can be used for feeding purposes, but the monohydride does not decompose easily. Therefore, as a trihydride, it absorbs tritium,
Next, when releasing tritium, the tritium obtained by decomposition is 2/3 of the absorbed amount, and the remaining 1/3 remains in the metal as a monohydride that does not decompose.
It is extremely uneconomical because it cannot be reused.

(Problems to be Solved by the Invention) The purpose of the present invention is to recover, store, and supply tritium gas in one device without using nuclear fuel materials or high temperatures of 500°C or higher, except for the following drawbacks: The purpose of the present invention is to provide a method for recovering, storing, and supplying tritium gas.

(Means for Solving the Problem) As a result of intensive research to achieve this objective, the inventor of the present application recovered tritium gas in the gas phase through a hydrogenation reaction of the intermetallic compound ZrCo at around room temperature, and hydrogen The present invention was developed based on the idea of storing tritium in the form of tritium, thermally decomposing it, and using it again to supply tritium gas.

In other words, tritium gas is heated at 10 ^-3 Pa at around room temperature using a material that has a hydrogen equilibrium pressure almost equivalent to that of uranium, the intermetallic compound ZrCo, or an alloy mainly composed of ZrCo (hereinafter simply referred to as ZrCo). The partial pressure is recovered to a certain level, and this is fixed in the hydride state.
The plan is to store the tritium, heat it to about 400°C, and then supply the recovered tritium at a pressure of around 1 atmosphere.

ZrCo used in the present invention is sealed in a closed container as a powder or small pieces. By contacting or flowing a gas containing tritium gas thereto, a hydrogenation reaction of ZrCo occurs and tritium gas is recovered. At this time, the partial pressure of tritium gas remaining in the gas phase is around 10 ^-3 Pa near room temperature,
Absorption capacity is approximately 150 tritium gas per gram of ZrCo
cc [NTP].

The absorbed tritium gas is directly stored as ZrCo hydride. Inside the container, tritium remains in the gas phase, and everything else is fixed as hydride, so there is little risk of contaminating the surrounding area due to leakage or releasing a large amount of tritium gas if the container is broken, and it can be stored as a gas. It is also safer than uranium, which is a natural and flammable hydride.

Tritium gas is supplied by heating this ZrCo hydride. The equilibrium partial pressure of this hydride is as shown in FIG. 1, and pure tritium gas can be obtained by heating the hydride to a temperature corresponding to the required pressure of tritium gas. For example, to obtain tritium gas at 1 atm, hydride can be heated to about 400°C;
Since no monohydride is formed as in the case of ZrNi, most of the tritium in the hydride is released as a gas.

An example of an apparatus for absorbing and releasing tritium gas according to the method of the present invention is shown in FIG.

Since ZrCo has the property of turning into powder when hydrogenated, it is practically convenient to hold it in a heat-resistant filter 2 as shown in 1 in the figure to prevent it from scattering.

When substantially pure hydrogen isotope gas is to be recovered, the gas is sucked into the sealed container 6 through the inlet 4 and recovered. If the target is a mixed gas containing other than hydrogen, transfer the gas from inlet 4 to inlet 5 .
By flowing through the gas, only hydrogen isotopes in the gas are selectively absorbed, and a gas containing almost no hydrogen can be obtained from 5 . Although the partial pressure of residual tritium (hydrogen) is lower as the temperature is lower, it is convenient for the operating temperature to be around room temperature, and in reality, the temperature of ZrCo during absorption is usually higher than room temperature due to hydrogenation heat generation. The reaction rate is sufficiently high at room temperature.

The recovered tritium is stored by closing the inlet 4 and the outlet 5 . At this time, the inside of the sealed container 6 is almost a vacuum or contains only gas other than hydrogen as a result of the above-mentioned absorption operation, and since the partial pressure of tritium is low, even if the container leaks or breaks, a large amount of tritium will not be released. .

Tritium gas is supplied by energizing the heater 3 . The temperature is set according to the required pressure of tritium gas as described above. Pure tritium gas is obtained by opening 4 or 5 when ZrCo 1 reaches a predetermined temperature. After taking out the required amount of tritium gas, if 4 or 5 is closed and the heater 3 is turned off, the tritium gas in the container 6 will be absorbed into ZrCo again.

As described above, tritium gas can be recovered, stored, and supplied by the method of the present invention in one device without using high temperatures. Unlike uranium, the material ZrCo is neither a nuclear fuel material nor a radioactive material, and it is not flammable in the air, so it is easy to handle, highly safe, and inexpensive. Note that the above series of operations can also be used as a method for separating and recovering low partial pressure or dilute tritium gas, as well as for purifying and pressurizing it.

[Brief explanation of drawings]

Figure 1 shows the equilibrium hydrogen pressure of various substances considered to be used for the same purpose as the present invention, that is, the hydrogen partial pressure in the gas phase when the substance and hydrogen come into contact and absorption or release occurs and equilibrium is reached. Represents temperature change. For example, for ZrCo, when the temperature is 50℃, the hydrogen partial pressure in the gas phase is
It absorbs or releases hydrogen up to 10 ^-3 tarr.
ZrNi, Ti, and Zr cannot release hydrogen at a pressure of 1 atmosphere or more at temperatures below 600°C. FIG. 2 illustrates an embodiment of the invention. In the figure, 1...ZrCo, 2...filter, 3
... Heater wire, 4... Gas inlet, 5... Gas outlet, 6... Sealed container.

Claims (1)

[Claims] 1. Collect tritium-containing hydrogen isotope gas in the gas phase through a hydrogenation reaction with the intermetallic compound ZrCo or an alloy containing ZrCo as a main component, store this as a hydride, and heat and decompose it. A method for recovering, storing and supplying tritium gas, characterized by supplying tritium gas again.