Chloride volatility is a method for the removal of elements, which form volatile chlorides, from fused molten chloride salts. Its principle of operation is the chemical oxidation of the elements in the spent fuel by atomic chlorine, which then escapes. It is being studied for reprocessing of nuclear fuel.
Some work has been undertaken on a closely related subject in the Czech Republic at Řež,[1] there an experimental rig exists in which simulated spent fuel is treated with chlorine gas diluted in nitrogen gas]] to form uranium hexachloride [2]. The uranium hexachloride is then distilled to remove other volatile metal chlorides and iodine chloride [3] [4]. The involatile mixture of fission products and minor actinides formed by the reaction of the chlorine gas with the uranium oxide is most suitable for further processing with 'dry' electrochemical processing (pyrochemical) nuclear reprocessing. The involitile lanthanide chlorides would be difficult to dissolve in the nitric acid used for aqueous reprocessing methods, such as SANEX, DIAMEX and SANEX, which use solvent extraction. chloride volatility is only one of several pyrochemical processes designed to reprocess used nuclear fuel.
Many pentachlorides and monochlorides have boiling and melting points similar to those of the corresponding fluorides, while many tetrachlorides, trichlorides and dichlorides have significantly lower boiling and melting temperatures than those of the corresponding fluorides.
chlorides by boiling and melting points
edit| chloride | Z | Boiling point | Melting point | Key halflife | Yield |
|---|---|---|---|---|---|
| Hexachlorides, heptachlorides - not converted | |||||
| SeCl6 | 34 | -46.6ºC | -50.8ºC | 79Se:65ky | .04% |
| TeCl6 | 52 | -39°C | -38°C | 127mTe:109d | |
| ICl7 | 53 | 4.8°C (1 atm) | 6.5°C (tripoint) | 129I:15.7my | 0.54% |
| MoCl6 | 42 | 34°C | 17.4°C | 99Mo:2.75d | |
| PuCl6 | 94 | 52°C (subl) | 62°C | 239Pu:24ky | |
| TcCl6 | 43 | 55.3°C | 37.4°C | 99Tc:213ky | 6.1% |
| UCl6 | 92 | 56.5°C (subl) | 64.8°C | 233U:160ky | |
| RuCl6 | 44 | 54°C | 106Ru:374d | ||
| RhCl6 | 45 | 70°C | 103Rh:stable | ||
| Pentachlorides, tetrachloride oxides | |||||
| BrCl5 | 35 | °C | °C | 81Br:stable | |
| ICl5 | 53 | °C | °C | 129I:15.7my | 0.54% |
| SbCl5 | 51 | 140°C | 4°C | 125Sb:2.76y | |
| RuOCl4 | 44 | °C | °C | 106Ru:374d | |
| RuCl5 | 44 | °C | °C | 106Ru:374d | |
| NbCl5 | 41 | 254°C | 204.7°C | 95Nb:35d | low |
| MoCl5 | 42 | 268°C | 194°C | 99Mo:2.75d | |
| Tetrachlorides, monochlorides | |||||
| ICl | 53 | 97.4°C | 27°C | 129I:15.7my | 0.54% |
| SnCl4 | 50 | 114.1°C | -33°C | 121m1Sn:44y 126Sn230ky |
0.013% ? |
| PdCl4 | 46 | 107Pd:6.5my | |||
| ZrCl4 | 40 | 331°C (subl) | 93Zr:1.5my | 6.35% | |
| UCl4 | 92 | 791°C | 590°C | 233U:160ky | |
| ThCl4 | 90 | 921°C | 770°C | ||
| AgCl | 47 | °C | °C | 109Ag:stable | |
| CsCl | 55 | 1295°C | 645°C | 137Cs:30.2y 135Cs:2.3my |
6.19% 6.54% |
| RbCl | 37 | 1390 °C | 718°C | 87Rb:49by | |
| ClLiNaK | °C | °C | stable | ||
| LiCl | 3 | >1300°C | 605°C | stable | |
| NaCl | 11 | 1465 °C | 801 °C | stable | |
| Trichlorides, dichlorides | |||||
| CdCl2 | 48 | 960°C | 564°C | 113mCd:14.1y | |
| InCl3 | 49 | 586°C | 115In:441ty | ||
| SrCl2 | 38 | 1250°C | 874°C | 90Sr: 29.1y | 5.8% |
| BaCl2 | 56 | 1560°C | 962°C | 140Ba:12.75d | |
| YCl3 | 39 | 1507°C | 721°C | 91Y:58.51d | |
| DyCl3 | 60 | 1530°C | 647°C | stable | |
| GdCl3 | 60 | 1580°C | 609°C | stable | |
| NdCl3 | 60 | 1600°C | 758°C | 147Nd:11d | |
| PrCl3 | 58 | 1710°C | 786°C | stable | |
| CeCl3 | 58 | 1730°C | 817°C | 144Ce:285d | |
| SmCl3 | 62 | decomp | 682°C | 151Sm:90y 146Sm:108y |
0.419% ? |
Missing: Pd 46, La 57, Pr 59, Pm 61, Eu 63 and up Inert: Kr 36, Xe 54
See also
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