DE2524128B2 - Process for the separation of isotopes - Google Patents

Description

The present invention relates to a method for separating isotopes from gaseous compounds, in which the connection partners are also present in a form that is not isotopically pure, through selective Suggestion, e.g. B. by means of laser radiation, and subsequent chemical or physical separation of the Reaction product. The separation of isotopes from gaseous compounds by selective excitation, where the wavelength of the radiation required for this is a rotational oscillation line of the desired Isotope-containing compound is known. The actual separation process of the excited molecules of the unexcited can be carried out physically, see DE-OS 23 12 194 and 21 20 401. However, a separation by chemical means has already become known, see DE-OS 19 59 767. This technology is mainly aimed at the enrichment of uranium, since this for the energy supply is of the utmost importance and must be looked for possibilities that have hitherto to replace extraordinarily expensive enrichment processes with more economical ones.

The previous proposals used UF6 as the starting material, as this is a relative one has high vapor pressure. It also has the advantage that the connection partner, i.e. the fluorine, is a Is a pure isotopic element. The rotational oscillation lines to be selected for the selective enrichment correspond so only two isotope compounds, namely those with uranium 238 and those with uranium 235.

It is also already known to use UCI ₆ for isotope enrichment as a basis, see GB-PS 12 84 620. The compound partner chlorine, however, occurs in two isotopic forms according to its natural occurrence, so that due to the large number of isotope compounds caused by it, there are also a large number partially overlapping • spectra are present. Selective separation is therefore only partially possible, which makes the process uneconomical. It has therefore been proposed in GB-PS that the chlorine of natural isotopic composition be replaced by only one chlorine isotope _{in the case of UCl 6}

i ". However, after the first separation stage has been carried out, this must be recovered for reasons of economy and returned to the starting materials.
For this purpose, a relatively cumbersome process is necessary, which requires an extremely high outlay in terms of equipment and thus does not meet the initially mentioned requirement for the greatest possible economic efficiency.

The task was therefore to create an economic

- "Find a procedure in which both connection partners can occur in the form of several isotopes.

This object is achieved according to the invention in a method in which one in the present Isotopic species determines compound compound

· - "> is selectively excited and the rest of the compound mixture after separation of the reaction product with a specially added amount of the compound partner in natural isotopic composition for Enabling an isotope exchange in connection

^iü and then returned to run through the separator again. This means that the natural composition of the isotopes of the reaction partner is restored and thus when it is passed through the again

^v ' separating device, the connection to be selectively excited is available again.

Special design measures of the method according to the invention emerge from subclaims 2 and 2.

With the process according to the invention, the starting amount of the starting compound can be depleted be pushed further and further - so no new one is needed until the desired degree of depletion is reached Natural uranium to be introduced into the process. Of the

In the case of uranium isotope separation, the application range of isotope separation processes known per se is thus extended beyond the previously only proposed compound UF ₆ - with fluorine as the pure isotope - to compounds, their connection partners

'">" does not need to be a pure isotope, so it is also off can consist of several isotopes. This means that even relatively small separation factors caused by only a small proportion of a selectively easily excitable isotopic composition of the starting compound,

^Y > can be used economically in comparison to the state of the art.

Such a starting compound is, for example, UCl ₆ . The natural chlorine is made up of the isotopes ³⁵ CI and ³⁷ Cl in a ratio of 76: 24.

^W) sets. Most of the UCl ₆ therefore lies as

2MU 35Q ₅ 37C1

before. The natural equilibrium distribution of ³⁵ Cl and ³⁷ Cl in the compound UCI ₆ is given in the following table:

U ³⁵ CI ₆
U ³ SCl ₅

³⁷ CI

Frequency: 18.6%
Frequency: 36.1%

U ³⁵ Cl ₄ ³⁷ CI ₂
U ³⁵ CI ₃ ³⁷ CI ₃
U ³⁵ CI ₂ ³⁷ Cl ₄
U ³⁵ CI ³⁷ Cl ₅
U ³⁷ CU
The connection

Frequency: 29.2%

Frequency: 12.6
Frequency: 3.3%

Frequency: 0.4%

Frequency: 0.02%

²³⁵ U ³⁵ Cl ₅ ³⁷ Cl
is therefore around 90 times more common than

²³⁵ U ³⁷ Cl ₅ ¹⁵ Cl.
For example, if only that

23SU J7 _C | ₅ 3SQ

selectively absorbed, this means that only 4% of the ^23S U-connection according to the prior art can be excited and separated. This corresponds to a hedge of 0.71% to 0.702% of the natural uranium. Since this is not sufficient, the depleted uranium would very often have to be fed to the separating device according to the principle of the aforementioned GB-PS until the desired degree of depletion is achieved.

According to the present invention, this problem can be solved much easier by the remainder of the UCU compounds remaining after the selective separation is treated in such a way that wi: the the selectively excitable compound

²³⁵ U ³⁷ Cl ₅ ³⁵ Cl

is present in the original quantity. This will be the remaining UCU coming from the separator heated together with chlorine of natural isotopic composition, so that according to the following functional equation

UCI ₆ ^ UCI ₄ + Cl ₂

an isotope exchange takes place and thus the natural mixture of UCU molecules is restored can.

This method can also be used, for example, with the compound U (BH ₄ J ₄ , only that here the isotope exchange is carried out with diborane.

The sequence of this method according to the invention is shown schematically in the figure. _{The starting material UCl 6} is located in the storage vessel 1; it flows through the separating device 2 in vapor form, in which the isotope mixture is selectively excited by a laser beam 21. The separation of the excited molecules takes place chemically or physically in the device 3, from where they are passed on to the collecting container 31. The unexcited and thus not secreted molecules reach the isotope equalization path 4, which

lu is provided with a heater 41. At the same time, chlorine gas of natural isotopic composition is introduced into this device from the storage container 5. The heating of this unit is preferably to a temperature of 120-200 ⁰ C is set to separate

ι ^r ) of UCU and chlorine, the gas mixture is then alternately cooled in containers 6 and 7 to 20-70 ° C., solid UCU separating out, while the chlorine, which is still gaseous, is condensed in container 8. If a sufficient amount of UCU has accumulated in container 6, the system switches over to container 7 for separation, and container 6 is heated to the temperature necessary for evaporation of the UCU. The compound, which has now been returned to its original isotopic composition, is fed to the actual separating device 2 via the line 9, the special isotope compound now present again being selectively excited and these excited molecules being separated out again in the device 3. This cycle becomes like this

ju long repeated until the depletion of the originally supplied amount of UCU in the one uranium isotope, z. B. ²³⁵ U has reached the desired degree. Then another amount of UCU of the original isotopic composition is made from the storage container 1

) 5 separator supplied.

The trick of isotope exchange used in this process requires only one relatively low energy, the effort necessary for its technical implementation is in terms of itself

■ to known excitation and separation devices 2 and 3 practically negligible.

After knowing the above principle, this process can be carried out by selecting suitable compounds and reaction partners, of course

-15 apply other isotope separation processes accordingly.

1 sheet of drawings

Claims (3)

Patent claims: 1. Process for the separation of isotopes from gaseous compounds, in which also the Connection partners are not present in isotopically pure form by selective excitation, e.g. B. by means of Laser radiation, and subsequent chemical or physical separation of the reaction products, characterized in that one of the types of isotopes present is definitely composed Compound is selectively excited that the remainder of the compound mixture after secretion of the reaction product with a specially supplied amount of the connection partner in a natural way Isotopic composition to enable an isotope exchange in connection and then returned to pass through the separator again. 2. The method according to claim 1, characterized in that ^{the compound LJCIö is used to separate the uranium isotopes 235} U and ²³⁸ U or their enrichment, wherein the connection partner chlorine from the isotopes ³⁵ CI and ³⁷ CI is contained in a natural ratio of 76:24 . 3. Process according to Claims 1 and 2, characterized in that the isotope exchange between the isotope mixture that has already passed through the separation system at least once and the supplied connection partner is carried out within a heated flow path.