# US 7,608,209 B2 · Use of sintered mixed carbonates for the confinement of radioactive carbon

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- Number: US 7,608,209 B2
- Document ID: US7608209B2
- Status: Granted
- Kind: B2
- Application number: 10/543,448
- Filed: 2004-10-21
- Published: 2006-08-31
- Granted: 2009-10-27
- Earliest claimed: 2003-10-28
- Assignees: Commissariat a l'Energie Atomique
- Inventors: Agnès Grandjean; Gilles Leturcq; Christophe Baron
- Web page: https://patentgrep.com/patent/US7608209B2

## CPC

- G21F 9/28: Treating solids
- G21F 9/02: Treating gases
- G21F 9/301: {by fixation in stable solid media}
- G21F: PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR (radiation protection by pharmaceutical means A61K8/00, A61Q17/04; in cosmonautic vehicles B64G1/54; combined with a reactor G21C11/00; combined with X-ray tubes H01J35/16; combined with X-ray apparatus H05G1/02)

## Abstract

The present invention relates to the use of a mixed carbonate of formula AB(CO3)2, in which A and B are different and chosen from alkali metals, alkaline-earth metals and rare earths, for the containment of radioactive carbon. This use may for example involve a process comprising: mixing CO2 having a radioactive carbon to be contained, or a simple carbonate of an alkali, alkaline-earth or rare-earth metal having a radioactive carbon to be contained, with an aqueous solution of a mixture of ACln and BClm or with an aqueous solution of a mixture of A(OH)n, and B(OH)m in order to obtain a precipitate of AB(CO3)2, where n and m are integers sufficient to compensate for the charge of A and B respectively; recovery of the AB(CO3)2 precipitate in powder form; and then pressing and sintering of the powder at a 20 temperature below the decarbonation temperature of the mixed carbonate manufactured in order to obtain sintered pellets of mixed carbonates for the containment of the radioactive carbon.

## Claims

### Claim 1

A radioactive carbon containment process, comprising a step of containing said radioactive carbon in a mixed carbonate of formula AB(CO3)(n+m)/2, the sintering temperature of which is below the decarbonation temperature of the mixed carbonate and the hardness of which is greater than or equal to 4 on the Mohs scale, in which A and B are different and chosen from the group consisting of alkali metals, alkaline-earth metals and rare earths, and in which n and m are positive integers such that the charge of AB(CO3)(n+m)/2 is neutral.

### Claim 2 (depends on 1)

The radioactive carbon containment process as claimed in claim 1, in which A and B are different and chosen from the group consisting of Na, K, Ca, Ba, Mg and Sr.

### Claim 3 (depends on 1)

The radioactive carbon containment process as claimed in claim 1, in which the mixed carbonate is BaCa(CO3)2.

### Claim 4 (depends on 1)

The radioactive carbon containment process as claimed in claim 1, in which the mixed carbonate is sintered for the containment of the radioactive carbon.

### Claim 5 (depends on 1)

The radioactive carbon containment process as claimed in claim 1, in which the radioactive carbon comes from a gaseous effluent of an irradiated nuclear fuel reprocessing plant.

### Claim 6

A radio carbon containment process, comprising the following steps:
a) mixing CO2 having a radioactive carbon to be contained, or a simple carbonate of an alkali, alkaline-earth or rare-earth metal having a radioactive carbon to be contained, with an aqueous solution of a mixture of ACln and BClm or with an aqueous solution of a mixture of A(OH)n and B(OH)m in order to obtain a precipitate of AB(CO3)(n+m)/2 where A and B are different and chosen from the group consisting of alkali metals, alkaline-earth metals, alkaline-earth metals and rare earths, and n and m are positive integers such that the charge of Aln, BClm, A(OH)n and B(OH)m is neutral;
b) recovering the AB(CO3)2 precipitate obtained in step a) in powder form;
c) optionally rinsing said powder; and
d) pressing the powder and sintering it at a sintering temperature below the decarbonation temperature of the synthesized mixed carbonates in order to obtain sintered pellets of mixed carbonates of formula AB(CO3)(n+m)/2, the hardness of which is greater than or equal to 4 on the Mohs scale, and containing the radioactive carbon in the sintered pellets of mixed carbonates.

### Claim 7 (depends on 6)

The process as claimed in claim 6, in which A and B are different and chosen from the group consisting of Na, K, Ca, Ba, Mg and Sr.

### Claim 8 (depends on 6)

The process as claimed in claim 6, in which the mixed carbonate is BaCa(CO3)2.

### Claim 9 (depends on 6)

The process as claimed in claim 6, in which the pressing is carried out at a pressure ranging from 10 to 20 MPa, and the sintering at said temperature for 1 to 3 hours.

### Claim 10 (depends on 6)

The Process as claimed in claim 6, in which the pressing is carried out at a pressure of 14 to 16 MPa, and the sintering at a temperature of 550° C. to 600° C. for 1 hour 45 minutes to 2 hours 30 minutes.

### Claim 11 (depends on 6)

The process as claimed in claim 6, in which the simple carbonate is obtained by trapping the radioactive carbon, in CO2 form, in accordance with a process chosen from the group consisting of a double alkali process, a direct hydroxide reaction process and a gas/solid process.

### Claim 12 (depends on 6)

The process as claimed in claim 6, in which the CO2 having a radioactive carbon to be contained, or a simple carbonate of an alkali, alkaline-earth or rare-earth metal having a radioactive carbon to be contained, comes from an effluent of an irradiated nuclear fuel reprocessing plant.