RU2377674C1 - Method of treating contaminated uranium material - Google Patents

Abstract

FIELD: nuclear physics. ^ SUBSTANCE: invention relates to a nuclear fuel cycle, and specifically to methods of treating contaminated hazardous 232U, 234U, 236U isotopes of uranium material on a gas centrifuge cascade. The method involves treating contaminated uranium material fed into a gas centrifuge cascade, obtaining low enriched uranium from cascade selection using natural uranium hexafluoride in an intermediate cascade selection into which natural uranium hexafluoride is fed, producing a product with low concentration of at least one of the hazardous 232U, 234U, 236U isotopes compared to contaminated material with mass ratio of contaminated uranium material to natural uranium hexafluoride taken for treatment equal to (125):100. ^ EFFECT: treating uranium material contaminated with hazardous impurities, obtaining quality material with permissible content of limiting hazardous isotopes, widening of the raw material base for fission plants, less separation work for processing material. ^ 7 cl, 4 dwg, 7 ex

Description

The invention relates to a nuclear fuel cycle, and in particular to methods of processing gas centrifuges contaminated with harmful isotopes ²³² U, ²³⁴ U, ²³⁶ U of a uranium feedstock on a cascade.

Contaminated uranium feed is contaminated natural uranium hexafluoride or a contaminated dump of the natural uranium hexafluoride enrichment process or regenerated uranium hexafluoride. Natural raw materials can be contaminated with harmful isotopes ²³² U, ²³⁴ U, ²³⁶ U when they are processed in technological equipment in which contaminated uranium materials were previously processed. In regenerated raw materials, harmful isotopes are formed during the irradiation of uranium fuel in reactors.

The use of refined raw materials will expand the raw material base of separation production.

Elevated concentrations of harmful isotopes ²³² U, ²³⁴ U lead to difficulties in the manufacture of nuclear fuel (powder, tablets, fuel rods), because are the cause of powerful and harmful radiation, and ²³⁶ U is the source of spurious neutron capture in a nuclear reactor.

The term "concentration" hereinafter means the mass fraction of one or another uranium isotope in a mixture of uranium isotopes.

Known methods for processing uranium materials, including their purification from harmful isotopes, in a cascade of gas centrifuges.

A known method for the purification of contaminated material used in the process of producing low enriched uranium hexafluoride (LEU) from highly enriched uranium (HEU) (RF patent No. 2225362, C01G 43/06, publ. 10.03.2004), in which the content of minor (harmful) isotopes in highly enriched uranium is reduced in a cascade of gas centrifuges simultaneously with the purification of highly enriched uranium from chemical impurities. The cascade has one stream (point) of supply of highly enriched uranium, a stream (point) of HEU selection with a reduced content (concentration) of the harmful isotope ²³⁴ U, and a dump stream (point). The concentration of the harmful ²³⁴ U isotope in purified uranium is still high (reduced from 1.06 and 1.08% in the feed stream to 0.93 and 1.048% in the selection stream, respectively, as described in examples 1 and 2 of the description of the mentioned patent) , which requires compliance with special radiation safety measures and complicates the further processing and storage of the resulting product.

A known method of processing contaminated uranium, used in the process for isotope reduction of regenerated uranium (RF patent No. 2236053, G21C 19/42, B01D 59/20, publ. 10.09.2004), which consists in increasing the content of the ²³⁵ U isotope in regenerated uranium to 2, . 0 ÷ 7,0% by weight - with a decrease in the absolute and relative concentrations of ^U-232 isotope, ²³⁴ U, ²³⁶ U, wherein a direct raw uranium enrichment in isotopically regenerate the gas centrifuge separation stage and the subsequent dilution of recovered uranium hexafluoride hexafluoride y ana natural origin. In this case, the raw uranium regenerate is enriched with the ²³⁵ U isotope to 10.0 ÷ 90.0 wt.%, After which it is diluted with natural uranium to a mass not exceeding the mass of the raw uranium regenerate - prototype.

The use of high degrees of enrichment in the process imposes additional difficulties on the implementation of the technology, and the use of dilution leads to significant losses in separation work and process efficiency.

The objective of the invention is to develop a method for processing contaminated with harmful impurities of uranium raw materials with obtaining high-quality raw materials with an acceptable content of limiting harmful isotopes and, thereby, expanding the raw material base of separation production, reducing the cost of separation work for processing raw materials.

The problem is solved in that in the method for processing contaminated uranium feed supplied to the gas centrifuge cascade, including the production of low enriched uranium from the selection of the cascade using natural uranium hexafluoride, in the intermediate selection of the cascade fed by natural uranium hexafluoride, a product with a reduced concentration is produced at least one of the harmful isotopes of uranium ²³² U, ²³⁴ U, ²³⁶ U compared with contaminated raw materials in the mass ratio of contaminated uranium of new raw materials and natural uranium hexafluoride spent on processing, (1 ÷ 25): 100.

Natural uranium hexafluoride of natural origin is supplied in the form of natural uranium hexafluoride with a concentration of ²³⁵ U isotope 0.711% or in the form of a selection or as a dump of the process of enrichment of natural uranium hexafluoride with a concentration of ²³⁵ U isotope, respectively, exceeding 0.711% or less than 0.711%.

The concentration of isotopes ²³² U, ²³⁴ U, ²³⁶ U in the product is regulated by the position of the feeding point of contaminated raw materials.

The concentration of the ²³⁵ U isotope in the product is controlled by the position of the intermediate selection point.

The concentration of the isotope ²³⁵ U in the product is 0.9 ÷ 1.1 of the concentration of the isotope ²³⁵ U in the feed.

The concentration of the ²³⁵ U isotope in the product is 0.3–1.5%.

As contaminated raw materials, regenerated uranium hexafluoride or contaminated natural uranium hexafluoride or a contaminated dump of the natural uranium hexafluoride enrichment process are used.

Figure 1 shows a diagram of the processing of regenerated raw materials to obtain a product of the same enrichment at ²³⁵ U as in the raw material.

Figure 2 shows a diagram of the processing of contaminated dump raw materials to obtain a product of the same enrichment at ²³⁵ U as in the raw material.

Figure 3 shows a diagram of the processing of contaminated raw materials to obtain a product enriched in ²³⁵ U compared with raw materials.

Figure 4 shows a diagram of the processing of contaminated natural uranium raw materials to obtain a product of the same enrichment at ²³⁵ U as in the raw material.

At stage 1 input stream 1 is fed 2 - natural uranium hexafluoride with a concentration of ²³⁵ U 0,711% and stream 3 contaminated raw uranium in the form of recovered uranium concentration of ²³⁵ U 0,8 ÷ 1,2%. At the output of cascade 1, three streams are obtained: LEU selection stream 4, intermediate selection stream 5 — a product with a reduced concentration of at least one of the harmful isotopes compared to contaminated raw materials (hereinafter, the product or purified product), and dump stream 6.

LEU obtained from stream 4 in the selection of cascade 1, configured to enrich LEU at ²³⁵ U to a given concentration in the range of 2–5%, is sent to the customer in container 7. The product obtained in stream 5 with a concentration of ²³⁵ U is the same as in stream 3 of the power supply of cascade 1, and is stored in container 8 for subsequent use as purified raw material in the production of LEU and HEU processing. The blade stream 6 with a concentration of ²³⁵ U 0.1 ÷ 0.3% in the container 9 is sent for storage.

At the input of the cascade 10 in FIG. 2, a stream 11 — natural uranium hexafluoride with a concentration of ²³⁵ U 0.711% and a stream 12 of contaminated raw materials in the form of a contaminated dump of separation production with a concentration of ²³⁵ U 0.1–0.5% are fed. At the output of cascade 10, three streams are obtained: KNO selection stream 13, intermediate selection stream 14 — a purified product, and dump stream 15.

The LEU obtained from stream 13 in the selection of the cascade 10, configured to enrich the LEU at ²³⁵ U to a given concentration in the range of 2-5%, is sent to the customer in the container 16. The product obtained in stream 14 with a concentration of ²³⁵ U, such as in stream 12 of power supply of cascade 10, is stored in container 17 for subsequent use as purified raw material in the production of LEU and HEU processing. The stream 15 of the dump with a concentration of ²³⁵ U 0.1 ÷ 0.3% in the container 18 is sent for storage.

At the inlet of the cascade 19 in Fig. 3, a stream 20 of natural uranium hexafluoride with a concentration of ²³⁵ U equal to 0.711% and a stream 21 of uranium hexafluoride of contaminated raw materials in the form of waste dumps with a concentration of ²³⁵ U 0.1 ÷ 0.4% are fed. At the output of cascade 19, three streams are obtained: the LEU selection stream 22, the intermediate selection stream 23 — the purified product, and the dump stream 24. The LEU obtained from stream 22 in the main selection of the cascade 19, configured to enrich the LEU at ²³⁵ U to a given concentration in the range 2 ÷ 5%, in a container 25 sent to the customer. The product obtained in stream 23 with a concentration of ²³⁵ U greater than in contaminated raw materials (in addition to purification and enrichment of raw materials) is stored in container 26 for subsequent use as purified raw materials in the production of LEU and HEU processing. The stream 24 of the dump with a concentration of ²³⁵ U 0.1 ÷ 0.3% in the container 27 is sent for storage.

At the input of the cascade 28 in Fig. 4, a stream 31 is supplied, which is a selection stream of an auxiliary ordinary cascade 29, to the input of which natural uranium 30 is fed. The stream 32 of raw materials in the form of contaminated natural uranium with a concentration of ²³⁵ U 0.711% is supplied to the additional power supply of the cascade 28 At the output of cascade 28, three streams are obtained: LEU selection stream 33, intermediate selection stream 34 is a purified product, and blade stream 35. A second blade stream 36 is obtained in cascade 29.

The LEU obtained from stream 33 in the selection of the cascade 28, configured to enrich the LEU at ²³⁵ U to a given concentration in the range of 2–5%, is sent to the customer in the container 37. The product obtained in stream 34 with a concentration of ²³⁵ U, such as in contaminated natural uranium of stream 32 powered by cascade 28, is stored in container 38 for subsequent use in the production of LEU and the processing of HEU. Stream 35 dump cascade 28 with a concentration of ²³⁵ U 0.1 ÷ 0.3% in the container 39 and stream 36 dump cascade 29 with a concentration of ²³⁵ U 0.1 ÷ 0.3% in the container 40 is sent for storage.

It should be noted that during the processing of contaminated raw materials to obtain a product of the same degree of enrichment of ²³⁵ U as the raw material, some difference in the concentration of ²³⁵ U in the product compared to the raw material can occur. The concentration of ²³⁵ U in the product can be 0.9 ÷ 1.1 of the concentration of ²³⁵ U in the feed. This is due to the fact that the ²³⁵ U concentration in the step feed stream having a concentration of ²³⁵ U close to the feedstock (where contaminated feed is supplied), and the sampling stream or dump stream of the same or one of the neighboring stages, having a ²³⁵ U concentration close to the feed , (where the product is taken from), may differ from each other.

Example 1. Processing the regenerated raw materials to obtain a product of the same degree of enrichment at ²³⁵ U as the raw materials (Fig. 1, Table 1).

The feed was fed to the cascade stage, the concentration of ²³⁵ U in which ≈0.85% is almost the same as in the feed. Received a product with a concentration of ²³⁵ U of 0.85%. The technical characteristics of the obtained LEU for harmful isotopes ²³² U, ²³⁴ U, ²³⁶ U and correspond to the Standard specifications for uranium hexafluoride with an enrichment of less than 5% in the isotope ²³⁵ U, ASTM C 996-04. The product ( ²³⁵ U concentration of 0.85% allows us to talk about it in the same way as enriched uranium) in terms of the content of harmful isotopes also meets the requirements of ASTM C 996 - 04. The work of separation for the processing of raw materials is not expended. The separation work is spent on the production of LEU in the main selection of the cascade (stream 4).

The mass ratio of contaminated uranium feed (stream 3) and natural uranium hexafluoride with a concentration of ²³⁵ U 0.711% isotope spent on processing (stream 2) is 1: 100.

Table 1 Options Main power (stream 2) Raw materials (stream 3) KNOW (stream 4) Product (stream 5) Blade (stream 6) The amount of UF ₆ , t 100,000 1,000 15,029 1,000 84,971 ²³⁵ U,% 0.711 0.85 3.6 0.85 0.2 ²³⁴ U,% 0.0054 0.016 0,03255 0.005608 0,000720 ²³⁶ U,% 0 0.35 0.01410 0.003883 0,001579 ²³² U,% 0 1.5 · 10 ^-7 9.810 ^-9 6.6 · 10 ^-10 2.210 ^-11 Work separation, thousand SWU 57,290

Example 2. Processing of regenerated raw materials to obtain a product of the same degree of enrichment at ²³⁵ U as the raw material. Offset point of regenerated feed. The concentration of ²³² U, ²³⁴ U, ²³⁶ U isotopes in the product is regulated by the position of the feeding point with contaminated raw materials (Fig. 1, Table 2).

It should be noted that in the case of processing regenerated raw materials, only small amounts can be purified, which is due to the need to comply with ASTM ²³² U requirements for LEU. In order to increase this amount and improve the composition of purified regenerated uranium, the feed point for raw materials, i.e. feed the feed to the stage of the cascade, the concentration of ²³⁵ U in which is much lower than in the feed. At the same time, during processing to obtain a product of the same concentration as in contaminated raw materials, the work of separation is expended. Table 2 shows the results when the feed point of regenerated uranium hexafluoride is displaced in stream 3 towards the first stage of cascade 1 — feedstock with a concentration of 0.85% by ²³⁵ U is fed to the power of the stage with a concentration of ²³⁵ U≈0.73%.

As can be seen from tables 1 and 2, when the feed point of the contaminated raw material is shifted towards the first stage of cascade 1 (Example 2), a larger amount of raw material than in Example 1 can be cleaned, while the degree of purification of the raw material and the composition of the LEU are improved. The product and LEU contain less harmful isotopes of uranium than the product and LEU obtained in example 1, with the deterioration of the composition of the dump in stream 6 of example 2.

On the operating time of LEU, the work of separation is expended. The additional costs of separation work (3.1%) are entirely related to the processing (refining) of raw materials.

table 2 Options Main power (stream 2) Raw materials (stream 3) KNOW (stream 4) Product (stream 5) Blade (stream 6) The amount of UF ₆ , t 100,000 2,000 15,029 2,000 84,971 ²³⁵ U,% 0.711 0.85 3.6 0.85 0.2 ²³⁴ U,% 0.0054 0.016 0,03218 0,005580 0,000909 ²³⁶ U,% 0 0.35 0.004279 0,001516 0,007446 ²³² U,% 0 1.5 · 10 ^-7 8.4 · 10 ^-9 9.710 ^-10 2.0-10 ^-9 Work separation, thousand SWU Effective - 57.290, actual - 59.106 (power utilization factor = 96.928%)

Technical characteristics of LEU and product for harmful isotopes ²³² U, ²³⁴ U, ²³⁶ U correspond to the Standard specifications for uranium hexafluoride with an enrichment of less than 5% for the isotope ²³⁵ U, ASTM C 996-04.

Despite the small amount of processed regenerated raw materials, on an industrial scale this will be quite significant.

Example 3. Processing the dump 0.34% at ²³⁵ U to obtain from it a product of the same degree of enrichment at ²³⁵ U as in the dump (figure 2).

Table 3 presents the data on the processing (purification) of dump uranium hexafluoride having a high content of ²³⁴ U and contaminated by ²³⁶ U.

Table 3 Options Main power (stream 11) Raw materials (stream 12) KNOW (stream 13) Product (stream 14) Blade (stream 15) The amount of UF ₆ , t 100,000 25,000 15,029 25,000 84,971 ²³⁵ U,% 0.711 0.34 3.6 0.34 0.2 ²³⁴ U,% 0.0054 0.0019 0,03224 0,001549 0,000756 ²³⁶ U,% 0 0.007 0,001938 0,001717 0,001212 Work separation, thousand SWU 57,290

As a result of processing in cascade 10, the product parameters for harmful isotopes are significantly improved. Technical characteristics of LEU for harmful ²³² U, ²³⁴ U, ²³⁶ U isotopes comply with the Standard Specifications for Uranium Hexafluoride with an enrichment of less than 5% in the isotope ²³⁵ U, ASTM C 996-04.

At the same time, separation work is not expended on the processing of raw materials.

The mass ratio of contaminated uranium feed (stream 12) and natural uranium hexafluoride with a concentration of ²³⁵ U of 0.711% isotope spent on processing (stream 11) is 25: 100.

Example 4. Processing of the blade 0.34% at ²³⁵ U with the time the product was produced with a concentration of 0.711% at ²³⁵ U (figure 3). The concentration of the ²³⁵ U isotope in the product is controlled by the position of the intermediate selection point.

Table 4 shows the results of calculations of cascade 19, which produces from 25 tons of contaminated dump with a concentration of 0.34% at ²³⁵ U a product in the amount of 6.849 tons of uranium with a concentration of 0.711% at ²³⁵ U. The separation work increases compared to the previous example 3 by 3.118 thousand SWU (60,408-57,290). The difference in separation work, equal to 3.118 thousand SWU, is spent on the enrichment of raw materials having 0.34% by ²³⁵ U, to obtain 6.849 tons of product 0.711% by ²³⁵ U.

The mass ratio of contaminated uranium feed (stream 21) and natural uranium hexafluoride with a concentration of ²³⁵ U of 0.711% isotope spent on reprocessing (stream 20) is 25: 100.

Table 4 Options Main power (stream 20) Raw materials (stream 21) KNOW (stream 22) Product (stream 23) Blade (stream 24) The amount of UF ₆ , t 100,000 25,000 15,029 6,849 103,121 ²³⁵ U,% 0.711 0.34 3.6 0.711 0.2 ²³⁴ U,% 0.0054 0.0019 0,03205 0.004249 0,000744 ²³⁶ U,% 0 0.007 0.002403 0,001021 0,001279 Work separation, thousand SWU 60,408

For comparison. Obtained in table 4, a product of 0.711% at ²³⁵ U with a concentration of the harmful isotope ²³⁴ U of 0.004249% is noticeably cleaner than a similar product of 0.711% at ²³⁵ U, which can be obtained directly in a conventional cascade with one selection from the same dump raw material. In a cascade with one selection, the product will have a concentration of ²³⁴ U 0.00447%.

Example 5. Processing the blade into a diluent for processing HEU in LEU. The concentration of the ²³⁵ U isotope in the product is controlled by the position of the intermediate selection point.

Table 5 shows the data on the processing of raw materials of the same amount (25,000 tons) and the same composition for ²³⁵ U and harmful isotopes, as in Table 3, but in the cascade in figure 3, into a product that can be a diluent for processing HEU in LEU. The processing costs of 25,000 tons of raw materials with a concentration of 0.34% for ²³⁵ U in 2.692 tons of diluent with a concentration of 1.5% for ²³⁵ U are 62.640-57.290 = 5.350 thousand SWU. (Comparison with table 3).

Table 5 Options Main power (stream 20) Raw materials (stream 21) KNOW (stream 22) Product (stream 23) Blade (stream 24) The amount of UF ₆ , t 100,000 25,000 15,029 2,692 107,278 ²³⁵ U,% 0.711 0.34 3.6 1,5 0.2 ²³⁴ U,% 0.0054 0.0019 0,03191 0,01071 0,000738 ²³⁶ U,% 0 0.007 0,002477 0,001333 0,001251 Work separation, thousand SWU 62,640

Example 6. The use of the product from table 4 in the form of purified reduced natural uranium with a concentration of 0.711% at ²³⁵ U for the production of diluent.

Table 6 shows the data on the operating time of the diluent (in a conventional cascade with one selection) from the product of 0.711% obtained in table 4 on cascade 19 of figure 3.

Table 6 Options Nutrition (Product of Table 4) Thinner (selection) Blade The amount of UF ₆ , t 6,849 2,989 3,860 ²³⁵ U,% 0.711 1,5 0.1 ²³⁴ U,% 0.004249 0,009475 0,000202 ²³⁶ U,% 0,001021 0,001883 0,000354 Work separation, thousand SWU 3,645

The total cost of the separation to obtain the diluent from table 6 is = 6.763 thousand SWU. Costs consist of 3.118 thousand SWU (product hours of table 4 in example 4, which serves as food in example 6) and 3.645 thousand SWUs (operating time of diluent in example 6). In direct processing of 0.34% ²³⁵ U into a diluent in Example 5, the costs are = 5.350 thousand SWU, i.e. less by 1,413 thousand SWU. This is because the concentration of the blade at ²³⁵ U in example 5 is greater. However, the diluent quality of ²³⁴ U in Example 6 is significantly better. At ²³⁶ U it is slightly worse, but from the point of view of processing HEU into LEU, it remains extremely good. This indicates the flexibility of the claimed method for use when operating the diluent.

The preparation of the diluent in two stages — the operating time from the dump 0.34% for ²³⁵ U of the product 0.711% for ²³⁵ U in Table 4 and the preparation of the diluent 1.5% for ²³⁵ U in Table 6 from it — can be compared with obtaining the same amount diluent with the same concentration of ²³⁵ U from the dump 0.34% of ²³⁵ U in the usual cascade with one selection.

Table 7 shows the preparation of a diluent from a dump with a concentration of ²³⁵ U 0.34% in a cascade with one selection.

Table 7 Options Food Thinner (selection) Blade The amount of UF ₆ , t 17,437 2,989 14,448 ²³⁵ U,% 0.34 1,5 0.1 ²³⁴ U,% 0.0019 0,009739 0,000278 ²³⁶ U,% 0.007 0,02303 0.003684 Work separation, thousand SWU 9,020

With the direct operating time of the diluent from the waste raw materials (Table 7), the content of ²³⁶ U in the diluent is 0.023%. This does not exceed ASTM requirements for LEU, but significantly more than the limit values for the processing of HEU into LEU. The variant of Tables 4 and 6 allows to reduce the content of ²³⁶ U to the required level for the diluent - 0.001883%, in addition, the quality of ²³⁴ U is improved, with significantly less separation work: 9.020 thousand SWU in Table 7 and the amount of 6.763 thousand SWU in Tables 4 and 6.

Example 7. The processing of contaminated natural raw materials using as the main feed of the cascade the selection flow of the enrichment process of natural uranium hexafluoride (Fig. 4, Tables 8 and 9).

Table 8 shows the results for obtaining a selection of 3.6% and a dump of 0.23% for ²³⁵ U from natural raw materials in cascade 29. Table 9 shows the results for obtaining a product of 0.711% for ²³⁵ U and 0.0053% for ²³⁴ U in cascade 28, the main power of which serves the selection of cascade 28.

In cascade 28 serves 5,000 tons of contaminated natural raw materials with a concentration of ²³⁴ U 0,0080%. In the intermediate selection of this cascade, the same 5,000 tons are obtained, but with a concentration of ²³⁴ U, 0.0053%, which meets the requirements of ASTM (0.0058% for ²³⁴ U). In this case, the work of separation on the production of this product is equal to zero.

The mass ratio of contaminated uranium feed (stream 32) and natural uranium hexafluoride with a concentration of ²³⁵ U of 0.711% isotope spent on processing (stream 30) is 5: 100.

Table 8 Options Power (stream 30) Selection (stream 31) Blade (stream 36) The amount of UF ₆ , t 100,000 14,266 85,734 ²³⁵ U,% 0.711 3.6 0.23 ²³⁴ U,% 0.0054 0,03246 0,0008949 Work separation, thousand SWU 50,598

Table 9 Options Main power (stream 31) Raw materials (stream 32) KNOW (stream 33) Product (stream 34) Blade (stream 35) The amount of UF ₆ , t 14,266 5,000 11,593 5,000 2,673 ²³⁵ U,% 3.6 0.711 4.4 0.711 0.13 ²³⁴ U,% 0,03246 0.0080 0,04100 0.005299 0,000469 Work separation, thousand SWU 4,555

In the inventive method, when processing contaminated uranium raw materials to produce a product with a reduced content of harmful isotopes, which is carried out simultaneously with the production of commodity low enriched uranium, redistribution of harmful isotopes between the product, commodity low enriched uranium and dump occurs, while a significant part of the harmful isotopes goes to low enriched uranium, without violating the quality requirements for low enriched uranium.

The inventive method has a high efficiency. Compared with conventional methods, the application of the proposed method allows to obtain products that are cleaner in terms of harmful isotopes, to reduce the cost of separation for the production of diluent for processing HEU into LEU, and to expand the raw material base for the production of uranium hexafluoride.

Claims (7)

1. A method of processing contaminated uranium feed supplied to a gas centrifuge cascade, including the production of low enriched uranium from a cascade selection using natural uranium hexafluoride, characterized in that in the intermediate selection of a cascade fed by natural uranium hexafluoride, a product with a reduced concentration is produced although least one of the hazardous uranium isotopes ²³² U, ²³⁴ U, ²³⁶ U in comparison with the contaminated feed at a weight ratio of uranium contaminated raw hex natural uranium fluoride consumed for processing (1 ÷ 25): 100. 2. The method according to claim 1, characterized in that the natural uranium hexafluoride is supplied in the form of natural uranium hexafluoride with a concentration of ²³⁵ U isotope 0.711% or in the form of a selection or as a dump of the process of enrichment of natural uranium hexafluoride with a concentration of ²³⁵ U isotope, respectively, exceeding 0.711% or less than 0.711%. 3. The method according to claim 1, characterized in that the concentration of isotopes in the product is regulated by the position of the feeding point with contaminated raw materials. 4. The method according to claim 1, characterized in that the concentration of ²³⁵ U isotopes in the product is controlled by the position of the intermediate selection point. 5. The method according to claim 1, characterized in that the concentration of the isotope ²³⁵ U in the product is 0.9 ÷ 1.1 of the concentration of the isotope ²³⁵ U in the feed. 6. The method according to claim 1, characterized in that the concentration of the ²³⁵ U isotope in the product is 0.3 ÷ 1.5%. 7. The method according to claim 1, characterized in that the recovered uranium hexafluoride or the contaminated natural uranium hexafluoride or the contaminated dump of the natural uranium hexafluoride enrichment process are used as contaminated raw materials.

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