DE2524128C3 - 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 UF ₆ as the starting material, which has a relatively high vapor pressure. It also has the advantage that the connection partner, i.e. the fluorine, is a pure isotope element. The rotational oscillation lines to be selected for the selective enrichment correspond to only two isotope compounds, namely those with uranium 238 and those with uranium 235.

It is also already known to use UCU as a basis for isotope enrichment, see GB-PS 12 84 620. The connection partner chlorine comes

however, according to its natural occurrence in two isotope forms, so that by the The large number of isotope compounds caused by this also include a large number of partially overlapping ones Spectra is present. Selective separation is therefore only partially possible, thereby reducing the process is uneconomical. In the GB-PS it has therefore been proposed that the chlorine be more natural in the case of the UCIj Replace isotopic composition with just one chlorine isotope. However, this must be done after the recovered first separation stage for reasons of economy and fed back to the starting materials will.

A relatively cumbersome procedure is therefore necessary for this, which is extremely high Requires outlay in terms of apparatus and thus also does not meet the initially mentioned requirement for the largest possible Profitability met.

The task aaher was to find an economical 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 Isotope types determined compound compound is selectively excited and the rest of the compound mixture after separation of the reaction product with a specially supplied amount of the connection partner in natural isotopic composition to enable an isotopic exchange in connection is brought and then returned for renewed passage through the separating device. this means that the natural composition of the isotopes of the reaction partner is restored and thus the connection to be selectively excited when it passes through the separating device again is available again.

Special design measures of the method according to the invention emerge from the subclaims 2 and 3.

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. The area of application of known isotope separation processes is thus in the case of uranium isotope separation via the previously only proposed compound UFb - with fluorine as a pure isotope - out Connections extended whose connection partner does not need to be a pure isotope, so also from 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, can be used economically in comparison to the state of the art.

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

^b0 sets. Most of the UCl ₆ therefore lies as

238U

³⁷ CI

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

³⁷ Cl

Frequency: 18.6%
Frequency: 36.1%

U 35Cl ₂ 37 _C I ₄

U 35Cl 37Q ₅

U 37Cl ₆

The connection

Frequency: 29.2%
Frequency: 12.6
Frequency: 3.3%
Frequency: 0.4%
Frequency: 0.02%

²³⁵ U 35 _C ] ₅

is therefore around 90 times more common than

²³⁵ U

For example, if only that

selectively absorbed, this means that only 4% of the 235 (j compound according to the previous state of the Technology can be stimulated and separated. This corresponds to a hedging of 0.71% to o.702% of natural uranium. Since this is not sufficient, the depleted uranium would very often have to go to the separator fed according to the principle of the aforementioned GB-PS until the desired degree of depletion is achieved.

According to the present invention, however, this problem can be solved much more simply by treating the remainder of UCl ₆ compounds remaining after the selective separation in such a way that the selectively excitable compound is restored

is present in the original quantity. To do this, the rest of the UCU coming from the separating device heated together with chlorine of natural isotopic composition, so that according to the following functional equation

UC1 ₆ 1 = »UCI ₄ 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 ) 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. In the pantry

Barrel 1 is the starting material UCI ₆ , it flows through the separating device 2 in vapor form, AOrin the mixture of isotopes is selectively excited by a laser beam 21. The excited molecules are separated chemically or physically in the device 3, from where they are passed on to the collecting container 31. The non-energized and thus not secreted molecules pass for isotopic equalization section 4 which is provided with a heater 41 at the same time more natural in this device chlorine gas isotopic composition is introduced from the storage container 5, the heating of this unit is preferably adjusted to a temperature of 120-200 ⁰ C to separation of UCI ₆ and chlorine is the gas mixture then partly cooled in the containers 6 and 7 to 20-70 ⁰ C whereby solid UCI ₆ separates is condensed while still gaseous chlorine in the container. 8 If a sufficient amount of UCI _{6 has} accumulated in container 6, a switch is made to container 7 for separation. Container 6 is heated to the temperature necessary for evaporation of the UCl _6. 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 is repeated until the originally supplied amount of UCl _{6 is} secured against the one uranium isotope, e.g. B. ²³⁵ U has reached the desired degree. _{Then a further amount of UCI 6 of the} original isotopic composition is again from the storage container 1

Separating device fed.

The trick of isotope exchange used in this process requires only one relatively low energy, which is necessary for its technical implementation with regard to the per se known excitation and separation devices 2 and 3 are practically negligible.

After knowing the above principle, this process can be carried out by selecting suitable compounds and reactants, of course, also apply analogously to other isotope separation processes.

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 related to enabling isotope exchange and then to run again duicii dir Separating device is returned. 2. The method according to claim 1, characterized in that the _{UCl 6} ^{compound is used to separate the uranium isotopes 235} Li and ²³⁸ U or their enrichment, in which the compound partner contains chlorine from the isotopes ³⁵ Cl and ³⁷ Cl in a natural ratio of 76:24 is 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.