BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Tc reduction by bacteria from soda lake DTSTART;VALUE=DATE-TIME:20171102T053000Z DTEND;VALUE=DATE-TIME:20171102T054500Z DTSTAMP;VALUE=DATE-TIME:20260416T041944Z UID:indico-contribution-346-1138@events01.synchrotron.org.au DESCRIPTION:Speakers: Konstantin German (A.N.Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences)\nOne of th e problematic types of LRW are alkaline wastes generated in some types of spent\nnuclear fuel reprocessing. Environmental friendly biological techni ques of LRW treatment\nare not widespread because of its extremely high sa lt contents and alkalinity usually not\nsuitable for organisms. The aim of this work was to explore the use of microorganisms\nfrom extremely alkali ne habitat to process liquid alkaline radioactive waste. This involved a\n search of promising microbial cultures from extremely alkaline lakes of th e Kulunda steppe\,\nwhich composition is close to alkaline wastes. The lak e sediments with medium (44-85 g/L)\nand extremely high (300-400 g/L) salt content were selected for investigations\; the microbial\nassociations\, which capable to reduce radionuclides were received. Experiments on reduct ion\nof technetium and uranyl acetate + pertechnetate were performed. The bacteria present in\nthe sediments and sludge of soda lakes reduced pertec hnetate ions in both experiments with\nhigh salinity (2.3 M - 84% techneti um reduced) and in experiment with a lower salinity (0.8\nM - 86% techneti um reduced) wherein uranium had no competitive effect on the recovery of\n technetium - in experiments with 1) technetium and 2) with technetium + ur anyl acetate\nreduced approx. 84% of pertechnetate. When using the mixed s ludge from lower salt content\nlake the amount of reduced technetium was l ower compared to the high salinity - 55-60%.\nThis work was supported by R FBR grant 15-05-08919\n\nhttps://events01.synchrotron.org.au/event/51/cont ributions/1138/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1138/ END:VEVENT BEGIN:VEVENT SUMMARY:Alkali technetium oxides and their relation to Tc loading in nucle ar waste glasses DTSTART;VALUE=DATE-TIME:20171102T051500Z DTEND;VALUE=DATE-TIME:20171102T053000Z DTSTAMP;VALUE=DATE-TIME:20260416T041944Z UID:indico-contribution-346-1136@events01.synchrotron.org.au DESCRIPTION:Speakers: John McCloy (Washington State University)\nBecause o f their radioactive nature\, solid technetium-99 oxides have been rarely s tudied\, and there is\na dearth of modern spectra and diffraction patterns in the literature. This publication aims to address\nthis by detailing a low-temperature synthesis method for pure\, crystalline alkali pertechneta tes\,\nalong with complete analysis by static and magic-angle-spinning nuc lear magnetic resonance\, Raman\,\nneutron diffraction (ND)\, and X-ray ab sorption spectroscopy (XAS). Insight gained from these\nstudies brings a d eeper understanding of the periodic chemistry of alkali (Na\,K\,Rb\,Cs) pe rtechnetates.\nAdditionally\, we report attempts to make 5- and 6-coordina te pertechnetate compounds of K\, Na\,\nand Li\, i.e. TcO5 - and TcO6 -. I t was found that higher coordinated species are very sensitive to\nwater\, and easily decompose into their respective pertechnetates. It was difficu lt to obtain pure\ncompounds\, but mixtures of the pertechnetate and other phases were frequently found\, as evidenced\nby XAS\, ND\, and Raman spec troscopy. Additionally\, we summarize other work on Tc loading\nin glasses \, effect on glass structure\, and salt formation in overloaded samples. F or glasses\, XAS\nchemometrics based on principal component analysis and l inear combination fitting suggests that Tc\nis speciated first as isolated Tc4+\, as Tc content is increased\, there is more Tc7+ which partitions\n first to K neighbors then to isolated sites. Preliminary work is reported assessing HTcO4 and related\ncompounds and their relationships to mechanis ms of Tc volatility\n\nhttps://events01.synchrotron.org.au/event/51/contri butions/1136/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1136/ END:VEVENT BEGIN:VEVENT SUMMARY:Comparison of thermal expansion of Tc and Re salts. DTSTART;VALUE=DATE-TIME:20171102T050000Z DTEND;VALUE=DATE-TIME:20171102T051500Z DTSTAMP;VALUE=DATE-TIME:20260416T041944Z UID:indico-contribution-346-1134@events01.synchrotron.org.au DESCRIPTION:Speakers: Gordon Thorogood (ANSTO)\n99Tc is the most significa nt long-lived product of uranium fission\, producing the largest fraction of the total long-lived radiation emissions of nuclear waste. Tc 7+ compo unds are highly mobile in the environment. Relatively little is known reg arding the solid state chemistry of Tc. Recently we studied the structural properties of (NH4)TcO4 (Tc7+) and confirmed that this is isostructural w ith (NH4)ReO4 adopting a tetragonal scheelite type structure in space grou p I41/a. The unit cell parameters of (NH4)TcO4 are strongly temperature d ependent with the structure showing negative thermal expansion along both the a- and c-axis\, albeit at different temperatures This behavior is sig nificantly different to that previously reported for the isostructural oxi de (NH4)ReO4\, although we note that the data for (NH4)ReO4 was collected at much lower resolution. Nevertheless it is clear in the literature that the thermal expansion behavior of (NH4)ReO4 is highly anisotropic. Despi te the difference in the thermal expansion between what we have observed f or (NH4)TcO4 and that described by others for (NH4)ReO4 it is likely that the origin of the anomalous thermal expansion in is the same in both cases \, namely it is a consequence of re-orientation of the ammonium ions in th e surrounding cage of eight oxygen atoms. To verify this for (NH4)TcO4 re quires we replace the ammonium cation with another small cation. Therefor e we have compared the thermal behavior of AReO4 with ATcO4 to determine i f Re oxides are suitable surrogates to predict the behavior of Tc oxides a nd how they may behave in the environment.\n\nhttps://events01.synchrotron .org.au/event/51/contributions/1134/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1134/ END:VEVENT BEGIN:VEVENT SUMMARY:Unusual redox neighborhood in technetium compounds DTSTART;VALUE=DATE-TIME:20171102T054500Z DTEND;VALUE=DATE-TIME:20171102T060000Z DTSTAMP;VALUE=DATE-TIME:20260416T041944Z UID:indico-contribution-346-1133@events01.synchrotron.org.au DESCRIPTION:Speakers: Konstantin German (A.N.Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences)\nTechetium has a great number of oxidation states (usually we say 9 but in fact much \nmore) and is evidently one of the elements with the most complicated che mistry. This is\ndue its position in the center of 4d elements row with 7 electrones available for chemical\nbonding. One of the very special option s complicating technetium chemistry is its ability to\ncluster formation a nd especially the possibility for Tc cluster to be reduced by consequtive\ naddition of electrones one by one. So the oxidation states of Tc in hydro chloric acid could be\n4+ (in K2TcCl6)\, 3+ (in [Bu4N]2Tc2Cl8)\, 2.5+ (in K3Tc2Cl8)\, 2+ (in K2Tc2Cl6)\, 11/6+\n(in [Me4N]3Tc6Cl14 and 10/6+ (in [Me 4N]2Tc6Cl12). We could imagine the number of\nhydroxides that could be for med sturting from these compounds. Another option is the\npresence of Tc a toms in different oxidation states within the same compound (p.e. Tc2Ac42\ nwhere Tc3+ and Tc7+ coexist in the one compound. New example is the red p ertechnic acid.\nAccording to new synthesis and X ray structure study it c ontains 4 TcO6 octahedra with\nTc6+\, that is usually considered extremely unstable and 16 Tc(VII) tetrahedra aranged in a\njoint compund [TcVI 4TcV II 1668]·16H2O: a = 11.1743(6)\, b = 12.8839(6)\, c = 14.0661(6)\nÅ\, α = 71.128(2)\, β = 69.015(2)\, γ = 74.340(2)◦\n\, P-1\, Z = 1. Of next extreme interest is\nnew Pu(III)(DMSO)6[TcO4]3 compound where reducing an d oxidizing parts coexist.\n\nhttps://events01.synchrotron.org.au/event/51 /contributions/1133/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1133/ END:VEVENT END:VCALENDAR