Process for producing enriched uranium having a .sup.235 U content of at least 4 wt. % via combination of a gaseous diffusion process and an atomic vapor laser isotope separation process to eliminate uranium hexafluoride tails storage

• US 5,419,820 A
• Filed: 06/02/1993
• Issued: 05/30/1995
• Est. Priority Date: 06/02/1993
• Status: Expired due to Fees

• Current Assignee: United States Enrichment Corporation (Centrus Energy Corp.)
• Original Assignee: United States Department of Energy
• Inventors: Hayden, Howard W. Jr., Horton, James A.
• Primary Examiner(s): Walsh, Donald P.
• Assistant Examiner(s): MAI, NGOCLAN THI
• Application Number:
  US08/070,741
• Time in Patent Office: 727 Days
• Field of Search: 204/157.2, 204/157.22, 423/DIG. 7, 423/258, 75/399, 55/34, 55/48
• US Class Current: 204/157.22
• CPC Class Codes: B01D 59/50 Separation involving two or more processes covered by different groups selected from groups B01D59/02, B01D59/10, B01D59/20, B01D59/22, B01D59/28, B01D59/34, B01D59/36, B01D59/38, B01D59/44
• CPC Class Codes: Y10S 423/07 Isotope separation

Abstract

An uranium enrichment process capable of producing an enriched uranium, having a ²³⁵ U content greater than about 4 wt. %, is disclosed which will consume less energy and produce metallic uranium tails having a lower ²³⁵ U content than the tails normally produced in a gaseous diffusion separation process and, therefore, eliminate UF₆ tails storage and sharply reduce fluorine use. The uranium enrichment process comprises feeding metallic uranium into an atomic vapor laser isotope separation process to produce an enriched metallic uranium isotopic mixture having a ²³⁵ U content of at least about 2 wt. % and a metallic uranium residue containing from about 0.1 wt. % to about 0.2 wt. % ²³⁵ U; fluorinating this enriched metallic uranium isotopic mixture to form UF₆ ; processing the resultant isotopic mixture of UF₆ in a gaseous diffusion process to produce a final enriched uranium product having a ²³⁵ U content of at least 4 wt. %, and up to 93.5 wt. % or higher, of the total uranium content of the product, and a low ²³⁵ U content UF₆ having a ²³⁵ U content of about 0.71 wt. % of the total uranium content of the low ²³⁵ U content UF₆ ; and converting this low ²³⁵ U content UF₆ to metallic uranium for recycle to the atomic vapor laser isotope separation process.

Claims

1. A uranium enrichment process capable of producing enriched uranium having a ²³⁵ U content of at least 4 wt. % which comprises:

a) fluorinating a partially enriched isotopic mixture of metallic ²³⁵ U/²³⁸ U from an atomic vapor laser isotope separation process, having a ²³⁵ U content of at least about 2 wt. %, to form an isotopic mixture of UF₆ ;

b) feeding the resultant isotopic mixture of UF₆ into a gaseous diffusion process; and

c) processing said UF₆ in said gaseous diffusion process until the desired ²³⁵ U content has been achieved.

2. The process of claim 1 including the further step of recycling low ²³⁵ U content UF₆ from said gaseous diffusion process back to said atomic vapor laser isotope separation process.

3. The process of claim 2 wherein said step of recycling said low ²³⁵ U content UF₆ back to said atomic vapor laser isotope separation process further includes the step of reducing said recycled UF₆ to metallic uranium and then introducing said metallic uranium into said atomic vapor laser isotope separation process as feed material.

4. The process of claim 3 including the further steps of recovering fluorine values from said low ²³⁵ U content UF₆ reduction step and recycling said recovered fluorine values to said fluorination step.

5. The process of claim 2 wherein said recycled low ²³⁵ U content UF₆ has a ²³⁵ U content within the range of from about 0.6 wt %. to about 0.8 wt. %, based on the total weight of uranium in said UF₆.

6. A uranium enrichment process which comprises:

a) feeding metallic uranium into an atomic vapor laser isotope separation process to produce a partially enriched metallic uranium isotopic mixture having a ²³⁵ U content of at least about 2 wt. % and a metallic uranium residue containing from about 0.1 wt. % to about 0.2 wt. % ²³⁵ U;

b) fluorinating said partially enriched metallic uranium isotopic mixture to form an isotopic mixture of UF₆ ;

c) processing said resultant isotopic mixture of UF₆ in a gaseous diffusion process to produce a final enriched uranium product having a ²³⁵ U content of at least 4 wt. % of the total uranium content of said finally enriched uranium product, and a low ²³⁵ U content UF₆ having a ²³⁵ U content of about 0.71 wt. % of the total uranium content of said low ²³⁵ U content UF₆ and

d) converting said low ²³⁵ U content UF₆ to metallic uranium for recycle to said atomic vapor laser isotope separation process.

7. The process of claim 6 wherein said final enriched uranium product has a ²³⁵ U content of at least 93.5 wt. % of the total uranium content of said finally enriched uranium product.

8. A uranium enrichment process characterized by the absence of UF₆ tails which comprises:

a) feeding metallic uranium into an atomic vapor laser isotope separation process;

b) recovering a partially enriched metallic uranium isotopic mixture of ²³⁵ U/²³⁸ U from said atomic vapor laser isotope separation process, having a ²³⁵ U content of at least about 2 wt. %, based on the total weight of uranium in said isotopic mixture;

c) fluorinating said partially enriched isotopic mixture of metallic ²³⁵ U/²³⁸ U from said atomic vapor laser isotope separation process to form an isotopic mixture of UF₆ ;

d) feeding said resultant isotopic mixture of UF₆ into a gaseous diffusion process;

e) passing said isotopic mixture of UF₆ through said gaseous diffusion process until the desired ²³⁵ U/²³⁸ U ratio has been achieved;

f) recovering a fully enriched UF₆ product;

g) recovering a low ²³⁵ U content UF₆ from said gaseous diffusion step, having a ²³⁵ U content ranging from about 0.6 wt %. to about 0.8 wt. %; and

h) reducing said low ²³⁵ U content UF₆ to metallic uranium for use as a feed to said atomic vapor laser isotope separation process.

9. The process of claim 8 including the further steps of recovering fluorine values from said low ²³⁵ U content UF₆ reduction step and recycling said recovered fluorine values to said fluorination step.

10. A uranium enrichment process which comprises:

a) feeding metallic uranium into an atomic vapor laser isotope separation process;

b) recovering a partially enriched metallic uranium isotopic mixture of ²³⁵ U/²³⁸ U from said atomic vapor laser isotope separation process having a ²³⁵ U content of at least about 2 wt. %, based on the total weight of uranium in said isotopic mixture;

c) fluorinating said partially enriched metallic uranium isotopic mixture of ²³⁵ U/²³⁸ U to form an isotopic mixture of UF₆ ;

d) feeding said isotopic mixture of UF₆ into a UF₆ uranium enrichment process selected from the group consisting of a gaseous diffusion process and a gas centrifuge process;

e) processing said UF₆ in said UF₆ uranium enrichment process until a fully enriched UF₆ product, comprising a ²³⁵ U/²³⁸ U ratio of over 4 wt. % ²³⁵ U, has been achieved;

f) recovering said fully enriched UF₆ product;

g) recovering a low ²³⁵ U content UF₆ from said gaseous diffusion process having a ²³⁵ U content ranging from about 0.6 wt %. to about 0.8 wt. %;

h) contacting said UF₆ residue with a reducing agent to reduce said UF₆ residue to metallic uranium for recycle into said atomic vapor laser isotope separation process; and

i) recovering fluorine values from said low ²³⁵ U content UF₆ reduction step and recycling said recovered fluorine values to said fluorination step.