82Se is a result of chemical transformation through SeF6 compound, and behavior of U-, Th-, Ra-impurities presented in such product (fluorine compounds) could be quite different of impurities in selenium produced accordingly to standard technology.
ILIAS, Jaca , Spain 5 of December 2006 Some properties of elementary selenium
Molecular composition of Se:
Vapor (at 700 – 1300 K): Se2 – Se8
Melt (at 494.3 – 958.4 K): mixture of cyclo-Se8, katenapoly-Sen
(n = 102 – 103), and polycyclo-Sen in chemical equilibrium.
Solid: Seα, Seβ – Se8, Sehex. - Sen
Melting Point, K. Se - 443; Se - 453; Sehex – 494,3
ILIAS, Jaca , Spain 5 of December 2006 The IChHPS& the IRE: content of work
1. Thermodynamic and experimental evaluation of chemical and aggregate forms of the limiting impurities and of their relative volatility in selenium produced from SeF6.
2. Experimental verification of purity of Se with natural isotopic composition with respect to the limiting impurities purified by multi-stage vacuum distillation and rectification. Verification of abilities of these methods during production of kilograms amounts of Se extracted from SeF6.
3. Selection of technological process scheme with optimization by numerical methods of the degree of purity, output capacity and reliability.
4. Fabrication of equipment for the process with output capacity of 5-10 kg/cycle.
5. Production of pilot lots, characterization of the product, modifications of the selected scheme and technological modes.
ILIAS, Jaca , Spain 5 of December 2006 Last stage of Se purification and Rn extraction
ILIAS, Jaca , Spain 5 of December 2006 Conclusion
At present the only technology for 82Se production is centrifugation method and only site for 100 kg- scale production is Svetlana (the ECP, Siberia)
“Chemical features” of impurities in such a product (chemical forms): fluorine compounds.
Multi-stages distillation and rectification methods of purification: the IChHPS and the IRE are ready to start purification of Se in the framework of ILIAS.