Decontamination of tritiated water
Methods and systems directed to the separation of tritium from an aqueous stream are described. The separation method is a multi-stage method that includes a first stage during which tritium of a tritium-contaminated aqueous stream is adsorbed onto a separation phase, a second stage during which the adsorbed tritium is exchanged with hydrogen in a gaseous stream to provide a gaseous stream with a high tritium concentration, and a third stage during which the tritium of the gaseous stream is separated from the gaseous stream as a gaseous tritium product.
1. A system for removal and recovery of tritium from a tritium-contaminated aqueous stream, the system comprising:
an enrichment column containing a solid separation phase, the solid separation phase comprising hydroxyl groups and having an isotopic separation factor of about 1.06 or greater, the enrichment column including a liquid inlet at a first end of the enrichment column for receiving the tritium-contaminated aqueous stream and a liquid outlet at a second end of the enrichment column for exit of a clean aqueous stream, the enrichment column further comprising a gaseous inlet at the second end of the enrichment column for receiving a gaseous flow that includes protium and/or deuterium in the form of a material selected from the group consisting of hydrogen gas, deuterium gas, hydrogen deuteride gas, and mixtures thereof, and a gaseous outlet at the first end of the enrichment column for exit of a tritium-enriched gaseous flow; and
a thermal cycling adsorption column in fluid communication with the enrichment column, wherein the thermal cycling adsorption column is an inverse separation column and includes a tritium separation material that preferentially adsorbs tritium over protium and deuterium at an adsorption temperature and that releases the adsorbed tritium at a release temperature.
2. The system of claim 1 , further comprising one or more additional thermal cycling adsorption columns in fluid communication with the first thermal cycling adsorption column, wherein the additional thermal cycling adsorption column(s) include a protium separation material that preferentially adsorbs protium over deuterium and tritium at an adsorption temperature.
3. The system of claim 2 , wherein the protium separation material comprises palladium.
4. The system of claim 1 , wherein the enrichment column has an inside diameter of about 5 feet or greater and a height of about 50 feet or greater.
5. The system of claim 1 , further comprising a second enrichment column in fluid communication with the thermal cycling adsorption column.
6. The system of claim 1 , the solid separation phase further comprising a catalyst.
7. The system of claim 6 , wherein the catalyst comprises a material selected from the group consisting of platinum, iron, cobalt, nickel, ruthenium, rhodamine, palladium, osmium, and iridium.
8. The system of claim 6 , the catalyst encouraging the transfer of tritium from the solid separation phase to a gas.
9. The system of claim 1 , wherein the solid separation phase comprises a plurality of particles.
10. The system of claim 1 , wherein the solid separation phase comprises a porous solid.
11. The system of claim 10 , the porous solid having an average pore diameter of 500 Angstroms or less.
12. The system of claim 1 , the solid separation phase having a surface area of 100 square meters per gram or greater.
13. The system of claim 1 , the solid separation phase comprising a material selected from the group consisting of a polymer, an alumina, a silica, an aluminum silicate, and a zeolite.
14. The system of claim 1 , the solid separation phase having an isotopic separation factor of about 1.1 or greater.
15. The system of claim 1 , the solid separation phase having an isotopic separation factor of about 1.2 or greater.
16. The system of claim 1 , wherein the solid separation phase comprises a gel.
17. The system of claim 1 , further comprising a heater upstream of the gaseous inlet of the enrichment column.
18. The system of claim 1 , wherein the liquid inlet is in fluid communication with an environmental source of the tritium-contaminated aqueous stream.
19. The system of claim 1 , wherein the solid separation phase is a hydrated solid separation phase comprising ions associated with water molecules of hydration, the water molecules of hydration being available for exchange with tritiated water molecules during use of the system.
20. The system of claim 1 , wherein the tritium separation material comprises a molecular sieve, a transition metal, activated carbon, alumina, silica, silica-alumina, clay, or a mixture thereof.
21. The system of claim 1 , wherein the solid separation phase has an isotopic separation factor of about 1.06 or greater for tritiated water.