BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Atomistic simulation of interfaces in glass/crystal composites for nuclear waste forms DTSTART;VALUE=DATE-TIME:20171101T033000Z DTEND;VALUE=DATE-TIME:20171101T034500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1213@events01.synchrotron.org.au DESCRIPTION:Speakers: Paul C. M. Fossati (Imperial College London)\nHigh-L evel Waste (HLW) resulting from fuel reprocessing is immobilised in a boro silicate glass matrix\, particularly in France and the UK.\nSome HLW compo nents have higher melting points than the glass\, and thus never disolve i nto the melt.\nOther crystalline phases may also form during fabrication d ue to limited solubility.\nSeparation could also occur later through a pro cess of devitrification.\nThe resultant waste form may therefore demonstra te significant heterogeneity with secondary crystal phases embedded in a glass matrix.\n\nThe purpose of this study is to improve understanding of the issues associated with such microstructures in vitrified wasteforms.\ nWe will present results from atomistic simulations showing properties of glass/crystal interfaces in a surrogate composite formed of (Na$_{2}$)$_{x }$(SiO$_{2}$)$_{1-x}$ glass and rutile TiO$_{2}$ crystals.\nThe potentials employed have been widely used for glass materials. We will discuss their applicability to glass/crystal composite structures.\nWe will show struct ural and energetic features predicted for these interfaces and consider th e effect of radiation damage.\n\nhttps://events01.synchrotron.org.au/event /51/contributions/1213/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1213/ END:VEVENT BEGIN:VEVENT SUMMARY:Unique capabilities and methods for analysing nuclear waste form m aterials using ANSTO’s landmark infrastructure DTSTART;VALUE=DATE-TIME:20171101T054500Z DTEND;VALUE=DATE-TIME:20171101T060000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1209@events01.synchrotron.org.au DESCRIPTION:Speakers: Gabriel Murphy (University of Sydney)\nIn situ inves tigations of nuclear waste form related materials under extreme conditions are highly desirable for understanding and optimising applications of the se materials\, however they are often exceedingly challenging from a safet y and radiological perspective. As a part of our investigations into actin ide materials\, we have developed a number of novel experimental methodolo gies which utilize ANSTO’s landmark research infrastructure\, the Opal n uclear reactor and Australian Synchrotron\, towards examining the behaviou r of actinide materials related to nuclear waste forms under extreme condi tions. This presentation will highlight some of our successes in advancing the study of actinide and nuclear materials including\n\n - High temperat ure in situ redox chemistry of uranium using X-ray absorption spectroscopy .\n\n - The behaviour of uranium oxides under high pressure ( >6 GPa) usin g neutron diffraction.\n\n - High temperature studies of thorium oxides us ing synchrotron X-ray and neutron diffraction.\n\n - Chemistry of uranium oxides under high purity hydrogen gas reduction and high temperature condi tions (1000 °C) using synchrotron X-ray diffraction.\n\nhttps://events01. synchrotron.org.au/event/51/contributions/1209/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1209/ END:VEVENT BEGIN:VEVENT SUMMARY:Sodalite waste forms for iodine DTSTART;VALUE=DATE-TIME:20171101T044500Z DTEND;VALUE=DATE-TIME:20171101T050000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1202@events01.synchrotron.org.au DESCRIPTION:Speakers: John McCloy (Washington State University)\nIodine-12 9\, released in the off-gas stream during nuclear fuel reprocessing\, is p roblematic due to its long half-life\, high mobility in the earth’s envi ronment\, incorporation into the human thyroid\, and difficulty in immobil izing it using traditional vitrification methods. Iodosodalite (Na8Al6Si6O 24I2) has been considered as to immobilize iodine-129 due to feasibility o f synthesis at low temperature (\n\nhttps://events01.synchrotron.org.au/ev ent/51/contributions/1202/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1202/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and characterization of brannerite UTi2O6 DTSTART;VALUE=DATE-TIME:20171031T221500Z DTEND;VALUE=DATE-TIME:20171031T223000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1198@events01.synchrotron.org.au DESCRIPTION:Speakers: adel mesbah (ICSM Marcoule\, France)\nThe share of n uclear energy in order to supply electricity continues to increase\, which makes a growing need for more uranium resources. Currently uraninite (UO2 ) and coffinite (USiO4) are the two most abundant and exploited minerals. With the exhausting of these resources\, other minerals are currently cons idered and are subject to multiple studies. Among them brannerite (UTi2O6) represents the third source of tetravalent uranium on Earth and could be considered for uranium recovery.1 However\, brannerite is known to be very difficult to dissolve quantitatively even in very aggressive conditions. 2 Consequently\, the multiparametric study of dissolution of this phase ha s to be studied in details.\nIn this work\, we first focused on the synthe sis of pure brannerite by developing new methods of synthesis free from he avy grinding steps in contrary of the alkoxide/nitrate based routes.3 The impact of several parameters were studied such as heating temperature of s ynthesis\, holding time and atmosphere. Therefore a new method was develop ed based on the preparation of hydroxides mixture then it direct heating u nder Ar or N2 atmosphere for 72 hours at 1300°C.\nFinally\, dissolution e xperiments were carried out under different conditions in order to provide multiparametric expression of the normalized dissolution rate.\n\n**Refer ences**\n\n1. IAEA. Uranium extraction technology. Technical reports se ries 1993\, 359\, \n2. Gilligan\, R.\; Nikoloski\, A. N. The extraction of uranium from brannerite – A literature review. Minerals Engineering 2015\, 71\, 34-48.\n3. Ringwood\, A. E.\; Kesson\, S. E.\; Reeve\, K. D .\; Levins\, D. M.\; Ramm\, E. J. In Radioactive Forms for the Future\; Lu tze\, W.\, Ewing\, R. C.\, Ed.\; 1988\; p 233.\n\nhttps://events01.synchro tron.org.au/event/51/contributions/1198/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1198/ END:VEVENT BEGIN:VEVENT SUMMARY:Preparation of Ln1-2xCaxThxPO4.nH2O rhabdophane-type as low precur sors to monazite-Cheralite ceramics DTSTART;VALUE=DATE-TIME:20171101T001500Z DTEND;VALUE=DATE-TIME:20171101T003000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1197@events01.synchrotron.org.au DESCRIPTION:Speakers: adel mesbah (Institut de Chimie Séparative de Marco ule\, UMR 5257 CEA/CNRS/UM/ENSCM\, Site de Marcoule\, BP 17171\, 30207 Bag nols-sur-Cèze cedex\, France)\nMonazite\, i.e. LnPO4 (Ln = La-Gd)\, has b een widely studied as specific ceramic for the conditioning of trivalent a nd tetravalent actinides.1 Owing to its chemical and structural flexibilit y\, the monazite allows a variety of possible substitutions following diff erent mechanisms.2 Among them\, the so-called cheralite-family\, i.e. Ln1- 2xCaxAnIVxPO4. In this frame\, the major part of protocols reported in the literature was based on solid-state chemistry routes. However\, this meth od requires the use of repetitive grinding steps and re-heating of actinid e bearing powders and usually forms heterogeneous compounds in term of cat ionic distribution. \nIn this work\, we present an alternative method base d on wet chemistry route to prepare thorium-based cheralites. It is based on the initial precipitation of Ln1-2xCaxThxPO4.nH2O3 low temperature prec ursors crystallizing in the rhabdophane type structure (monoclinic\, C2 sp ace group).4 A multiparametric study allowed the determination of the appr opriate conditions to form homogeneous and single phase powders. Then thes e hydrated precursors were converted to monazite-cheralite ceramics throug h thermal treatment. A coupled in situ PXRD/TGA allowed the identification of the different dehydration steps before the irreversible stabilization of the cheralite anhydrous compounds.5 Moreover\, since such hydrated phas es could also control the release of radionuclides from the ceramics in th e field of underground repository\, dissolution and solubility experiments have been finally carried out.\n\n**References**\n\n1. Dacheux\, N.\; Clavier\, N.\; Podor\, R. American Mineralogist 2013\, 98 (5-6)\, 833-847. \n2. Clavier\, N.\; Podor\, R.\; Dacheux\, N. Journal of the European C eramic Society 2011\, 31 (6)\, 941-976.\n3. Qin\, D.\; Mesbah\, A.\; Ga usse\, C.\; Szenknect\, S.\; Dacheux\, N.\; Clavier\, N. Journal of Nuclea r Materials 2017\, 492\, 88-96.\n4. Mesbah\, A.\; Clavier\, N.\; Elkaim \, E.\; Gausse\, C.\; Kacem\, I. B.\; Szenknect\, S.\; Dacheux\, N. Crysta l Growth & Design 2014\, 14 (10)\, 5090-5098.\n5. Mesbah\, A.\; Clavier \, N.\; Elkaim\, E.\; Szenknect\, S.\; Dacheux\, N. Journal of Solid State Chemistry 2017\, 249\, 221-227.\n\nhttps://events01.synchrotron.org.au/ev ent/51/contributions/1197/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1197/ END:VEVENT BEGIN:VEVENT SUMMARY:Thorium incorporation in phosphates matrices: the case of xenotime DTSTART;VALUE=DATE-TIME:20171101T004500Z DTEND;VALUE=DATE-TIME:20171101T010000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1195@events01.synchrotron.org.au DESCRIPTION:Speakers: adel mesbah (ICSM Marcoule\, France)\nThe management and the conditioning of radwaste represents a major challenge in the nucl ear industry. Therefore a variety of host matrices have been studied\, inc luding several phosphate based ceramics.1 They represent promising candida tes for the specific conditioning of actinides (III\, IV) owing to their e asy way of preparation and high chemical durability.2\nThe incorporation o f actinides in such phases has been extensively studied through solid-stat e routes. Thus\, it often requires repetitive grinding steps and re-heatin g to avoid the formation of heterogeneous compounds.3 For such reasons\, t he synthesis of target compounds in aqueous solution were developed to pre pare pure and homogenous phases. \nIn this study\, a particular attention was paid to the incorporation of tetravalent actinides (Th4+\, U4+) in the zircon structure type through the coupled mixed (An(IV) + SiO4 / Ln(III) + PO4) substitution.\nIn this frame\, solid solutions of Er-xThx(PO4)1-x(S iO4)x were obtained in application of the method developed to prepare pure coffinite (USiO4)\, i.e. hydrothermal conditions at 250°C for 7 days.4 T he analysis of the PXRD data showed the formation of single phases. The st ructure crystallizes in the zircon-type structure (I41/amd group\, tetrago nal system) as observed for the end-members ThSiO4 and ErPO4. From Rietvel d refinements\, the formation of a complete solid solution was confirmed i n agreement with the Vegard’s law. A thorough analysis was also carried out by Raman spectroscopy and EXAFS at the Er and Th edges and showed an e xciting structural evolution.5 \n\n**References**\n\n1. Dacheux\, N.\; Clavier\, N.\; Robisson\, A. C.\; Terra\, O.\; Audubert\, F.\; Lartigue\, J. É.\; Guy\, C. Comptes Rendus Chimie 2004\, 7 (12)\, 1141-1152.\n2. Dacheux\, N.\; Clavier\, N.\; Podor\, R. American Mineralogist 2013\, 98 ( 5-6)\, 833-847.\n3. Terra\, O.\; Dacheux\, N.\; Audubert\, F.\; Podor\, R. Journal of Nuclear Materials 2006\, 352 (1)\, 224-232.\n4. Mesbah\, A.\; Szenknect\, S.\; Clavier\, N.\; Lozano-Rodriguez\, J.\; Poinssot\, C .\; Den Auwer\, C.\; Ewing\, R. C.\; Dacheux\, N. Inorganic Chemistry 2015 \, 54 (14)\, 6687-6696.\n5. Mesbah\, A.\; Clavier\, N.\; Lozano-Rodrigu ez\, M. J.\; Szenknect\, S.\; Dacheux\, N. Inorg Chem 2016\, 55 (21)\, 112 73-11282.\n\nhttps://events01.synchrotron.org.au/event/51/contributions/11 95/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1195/ END:VEVENT BEGIN:VEVENT SUMMARY:New route for synthesis of Synroc-like ceramic using non-selective sorbent LHT-9 DTSTART;VALUE=DATE-TIME:20171101T060000Z DTEND;VALUE=DATE-TIME:20171101T061500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1189@events01.synchrotron.org.au DESCRIPTION:Speakers: Bella Zubekhina (researcher\, V.G. Khlopin Radium In stitute (KRI)\, St-Petersburg\, Russia)\nImmobilization of bulk liquid hig h level waste (HLW) in Synroc ceramic is well-known reliable way for final isolation of waste from biosphere. It is proposed the alternative method of synthesis of titanate Synroc-like ceramic. Radionuclide incorporation i nto crystalline titanate host-phases can be provided as a result of direct radionuclide sorption from liquid HLW using non-selective sorbent – lay ered hydrazinium titanate (LHT-9). Such an approach allows excluding expen sive multi-stage procedure of precursor preparation. The precipitate obtai ned after sorption can be easily transformed into Synroc-like ceramic by c old pressing and sintering in air at 1000-1100°. The highly radioactive s amples of titanate ceramic loaded with 10 wt.% of real HLW were synthesize d and studied at KRI hot-cell facility. Chemical durability of these sampl es was tested using MCC-1 static leach test (in distilled water at 90°C) and the leach rate was found to be comparable with Synroc ceramic.\n\nhttp s://events01.synchrotron.org.au/event/51/contributions/1189/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1189/ END:VEVENT BEGIN:VEVENT SUMMARY:A New Method for Production of Glass-Y2Ti2O7 Pyrochlore DTSTART;VALUE=DATE-TIME:20171101T031500Z DTEND;VALUE=DATE-TIME:20171101T033000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1187@events01.synchrotron.org.au DESCRIPTION:Speakers: Linggen Kong (Australian Nuclear Science and Technol ogy Organisation)\nThe actinide immobilisation research group at ANSTO has been investigating pyrochlore glass-ceramics for plutonium immobilisation . A novel method of glass ceramic preparation via a soft chemistry route h as been designed recently. Significant advantages over a more traditional mixed oxide route include removal of the need for an organic solvent in sy nthesis and milling steps\, and product devoid of potentially deficient mi nor phases. Glass-Y2Ti2O7 pyrochlore was fabricated by sintering the mixtu re of glass precursor powder and (YTi)-composite prepared by a soft chemis try route. XRD and Raman confirmed phase pure pyrochlore crystallized in-s itu in amorphous glass matrix at 1200oC. Pyrochlore formation in glass was independent of cooling rates and addition of metal fluorides. Glass matri x was able to accommodate/dissolve small amounts of impurities and the mea n pyrochlore particle size was between 1 and 2 µm in glass.\n\nhttps://ev ents01.synchrotron.org.au/event/51/contributions/1187/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1187/ END:VEVENT BEGIN:VEVENT SUMMARY:New aspects of U(V) chemistry in oxo-materials: from ambient to ex treme conditions DTSTART;VALUE=DATE-TIME:20171101T051500Z DTEND;VALUE=DATE-TIME:20171101T054500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1185@events01.synchrotron.org.au DESCRIPTION:Speakers: Evgeny Alekseev (Forschungszentrum Jülich)\nUsing e xtreme pressure (10GPa/1200°C) we obtained a new modification of U2O5 wit h an extraordinary dense structure. The crystal structure of resulting HP (high pressure)-U2O5 is dramatically differs from ambient pressure polymor ph so called delta-U2O5. The structure of HP-U2O5 is more related to the c ubic UO2 than to the layered delta-U2O5. Using state of the art ab initio methods we reveal the stability ranges of both ambient and high pressure f orms of U2O5 and demonstrated a potential pathway of phase transition unde r pressure.\nIn second case we demonstrated that the pentavalent uranium ( U(V)) can be stabilized in [Ln(UVO2)W4O14] (Ln = Nd-Tm and Y) series via a liovalent substitution of Ca2+ cations. We confirmed U(V) stabilization us ing state of the art methods such as U M4 edge high energy resolution X-ra y absorption near edge structure (HR-XANES).Magnetic study reveals low tem perature ordering of 5f1 and 4fn systems. All the phases tend to demonstra te the antiferromagnetic properties with significant difference between pu re 5f1 system (Y-beating phase) and 5f1-4fn compounds (Nd-Tm).\n\nhttps:// events01.synchrotron.org.au/event/51/contributions/1185/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1185/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and Structure of Novel Oxide Compounds Containing RE = Y \, Yb\, Gd\, Sm\, and La and M = Zr\, Ti\, and Sn DTSTART;VALUE=DATE-TIME:20171031T220000Z DTEND;VALUE=DATE-TIME:20171031T221500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1182@events01.synchrotron.org.au DESCRIPTION:Speakers: Greg Lumpkin (ANSTO)\nWith the aim of creating novel ceramics with high radiation tolerance and ionic mobility\, multiple samp les with A-B-O stoichiometries ranging from 215 to 227 were synthesized an d characterized by a combination of SEM\, XRD\, and TEM methods. Single-ph ase defect-fluorite-type compounds with A = Sm or Yb and B = Ti\, Zr\, and /or Sn are reported\; whereas\, pyrochlore compounds were also found as a second major RE-phase in numerous samples. We describe some interesting TE M data showing selected area diffraction patterns with complex modulations . The details of the modulation wave vectors observed in these samples are reported in some detail. The use of ionic radii to predict the structure of these ceramics appears to be substantially limited by Sn-O bonding char acteristics and somewhat limited for zirconate compounds. Some single phas e ceramics were irradiated with a low dose of helium and no significant ra diation damage was observed by comparative GIXRD and nano-indentation.\n\n https://events01.synchrotron.org.au/event/51/contributions/1182/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1182/ END:VEVENT BEGIN:VEVENT SUMMARY:The Fabrication and Characterisation of Novel Complex Ceramic Oxid es (Ln2TiO5) For Polyphase Ceramic Waste-Forms. DTSTART;VALUE=DATE-TIME:20171031T230000Z DTEND;VALUE=DATE-TIME:20171031T231500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1181@events01.synchrotron.org.au DESCRIPTION:Speakers: Robert Aughterson (ANSTO)\nThe structure types withi n the Ln2TiO5 (Ln = lanthanides) system have similarities with many of the proposed phases within the titanate ceramic waste-form Synroc. Certain co mpounds might also be suitable for inert matrix fuel applications. Previou s studies have shown a relationship between lanthanide radii and polymorph type for the Ln2TiO5 system. By using multiple lanthanides the average la nthanide radius can be controlled and so the structure. In this study four different combinations of lanthanide titanates were fabricated with the a im of producing single phase\, novel design materials with cubic symmetry. Whilst it is possible to fabricate homogeneous materials with the general Ln2TiO5 stoichiometry using multiple lanthanides there appears to be limi ted solubility. The ratio of the lanthanides influences the final structur e type and also the solubility. The structure type influences the heavy io n irradiation response of these compounds and we report on TEM in-situ exp erimental results related to this.\n\nhttps://events01.synchrotron.org.au/ event/51/contributions/1181/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1181/ END:VEVENT BEGIN:VEVENT SUMMARY:Radioactive Iodine-129 Capture in Mixed Cation Sodalites: ab initi o modelling DTSTART;VALUE=DATE-TIME:20171101T050000Z DTEND;VALUE=DATE-TIME:20171101T051500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1179@events01.synchrotron.org.au DESCRIPTION:Speakers: EUGENIA KUO (Australian Nuclear Science and Technolo gy Organisation)\nSodalites have been investigated experimentally for the capture and long-term containment of iodine-129\, a significant and hazard ous waste product of the nuclear fuel cycle. Sodalites are zeolite-type st ructures commonly occurring in nature in alkaline igneous rocks and having the prototype formula Na$_8$(AlSiO$_4$)$_6$Cl$_2$. The crystal structure is based around $\\beta$-cages consisting of corner-sharing SiO$_4$ and Al O$_4$ tetrahedra. In the centre of the $\\beta$-cage is an anion X. Iodine captured by sodalites sits in the centre of the $\\beta$-cages as iodide anions. Silver iodide (AgI) plays an important role in the capture and sub sequent processing of iodine-129 in the nuclear fuel cycle. Using *ab init io* density functional theory (DFT) modelling\, we investigate the energet ics and feasibility of iodine capture and containment in mixed cation soda lites Na$_{8-x}$Ag$_x$(AlSiO$_4$)$_6$I$_2$\, and compare the results with experimental observations.\n\nhttps://events01.synchrotron.org.au/event/51 /contributions/1179/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1179/ END:VEVENT BEGIN:VEVENT SUMMARY:Structural incorporation of Cm3+ and Pu3+ in phosphate ceramics wi th monazite structure. DTSTART;VALUE=DATE-TIME:20171101T003000Z DTEND;VALUE=DATE-TIME:20171101T004500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1162@events01.synchrotron.org.au DESCRIPTION:Speakers: Stefan Neumeier (Forschungszentrum Jülich GmbH\, In stitute of Energy and Climate Research - IEK-6: Nuclear Waste Management a nd Reactor Safety\, 52425 Jülich\, Germany)\nPhosphate ceramics with mona zite structure are considered as potential waste forms for the conditionin g of specific nuclear waste streams (e.g. minor actinides and plutonium) d ue to their outstanding properties. In this study\, the incorporation of a ctinides (Cm3+ and Pu3+) into the monazite structure has been investigated combining X-ray diffraction (XRD) as well as X-ray absorption- (XAS) and time-resolved laser fluorescence spectroscopy (TRLFS). \nThe results demon strate the incorporation of the actinides on defined lanthanide lattice si tes in the monazite ceramics. From TRLFS measurements of Cm-doped (50 ppm) (La\,Gd)PO4 solid solutions\, a decrease of short-range order for the sol id solution compositions was observed in comparison to the end-members. Ad ditionally\, XAS investigations on pure-phase La1-xPuxPO4 (x = 0.01 – 0. 15) solid solutions verify the incorporation of plutonium in the +III oxid ation state in the monazites. The results provide a refined structural ins ight into mechanisms of actinide incorporation into monazite ceramics and solid solution formation.\n\nhttps://events01.synchrotron.org.au/event/51/ contributions/1162/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1162/ END:VEVENT BEGIN:VEVENT SUMMARY:Partitioning of Ce\, as a Simulant for Pu\, in a Multiphase Cerami c Nuclear Waste Form DTSTART;VALUE=DATE-TIME:20171031T224500Z DTEND;VALUE=DATE-TIME:20171031T230000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1140@events01.synchrotron.org.au DESCRIPTION:Speakers: Zhaoming Zhang (ANSTO)\nA multi-phase titanate waste form was synthesized using high temperature sintering in air or Ar with t he composition of Ca0.71Y0.088Ce0.52Hf0.22Ti2Ox. The phase assemblage was investigated as a function of the sintering atmosphere. X-ray diffraction measurements indicated that oxidizing sintering atmosphere (air) favors th e formation of pyrochlore\, whereas neutral environment (Ar) promotes the formation of perovskite\, although both sintering atmospheres produced sam ples containing three phases (pyrochlore\, perovskite and rutile under air or zirconolite\, perovskite and rutile under Ar). Scanning electron micro scope (SEM) analysis revealed that Ce is present in perovskite and pyrochl ore (or zirconolite)\, but not in rutile. Micro-X-ray-Absorption-Near-Edge -Structure (micro-XANES) measurements conducted at the Ce L-edge\, in comb ination with electron energy loss spectroscopy (EELS)\, showed that Ce4+ p refers to inhabit the pyrochlore (or zirconolite) phase and Ce3+ the perov skite phase. This knowledge is valuable for the further development of ti tanate waste forms to immobilize Pu.\n\nhttps://events01.synchrotron.org.a u/event/51/contributions/1140/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1140/ END:VEVENT BEGIN:VEVENT SUMMARY:Current advances on titanate-based glass-ceramics for actinide imm obilization DTSTART;VALUE=DATE-TIME:20171101T024500Z DTEND;VALUE=DATE-TIME:20171101T030000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1139@events01.synchrotron.org.au DESCRIPTION:Speakers: Yingjie Zhang (ANSTO)\nGlass-ceramics have attracted recent attention as they have the advantage of combining the chemical fle xibility of glasses with the excellent durability of ceramics\, making the m potential waste forms for the immobilization of actinide wastes with pro cessing chemicals. Glass-ceramics based on titanate ceramic phases\, e.g. zirconolite\, pyrochlore and brannerite have been developed at ANSTO. The formations of these titanate dominated glass-ceramics have been demonstrat ed with uranium as proof of concept and plutonium with gadolinium and/or h afnium as neutron absorbers. This talk will focus on the current advances in the field including the formation and crystallization of titanate phase s in glass\, structure and microstructure characterization\, actinide inco rporation and actinide valences.\n\nhttps://events01.synchrotron.org.au/ev ent/51/contributions/1139/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1139/ END:VEVENT BEGIN:VEVENT SUMMARY:U-rich ceramics for Spent Fuel or Acidic 99Mo Production ILW DTSTART;VALUE=DATE-TIME:20171101T023000Z DTEND;VALUE=DATE-TIME:20171101T024500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1137@events01.synchrotron.org.au DESCRIPTION:Speakers: Eric R Vance (ANSTO)\nSpent fuel has long been unoff icially classified as HLW which is cooled for a few years to allow the dis sipation of short-lived fission products and then is to be contained in th ick-walled Cu or carbon steel containers for deep repository disposal wher e it is argued that the containers will perform immobilisation for ~105 yr . However immobilisation assumes highly reducing conditions in which UO2 i s essentially unreactive and even water-soluble fission products will be c ontained. The only published engineered waste form for spent UO2 fuel is s ynroc-F in which the U concentration is nearly 50 wt.% and the fission pro ducts are incorporated in resistate titanate mineral phases. We have tried to extend this concept by hot isostatic pressing glass-ceramics in which synroc-F constitutes the ceramic phase and the glass furnishes a second ph ase for fission product immobilisation and increases the general reactivit y. We have also used the same approach for acidic 99Mo production ILW.\n\n https://events01.synchrotron.org.au/event/51/contributions/1137/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1137/ END:VEVENT BEGIN:VEVENT SUMMARY:Solubility of the rhabdophane\, LnPO4.0.667 H2O (Ln = La to Dy): i mplications for the long-term stability of monazite matrices. DTSTART;VALUE=DATE-TIME:20171031T234500Z DTEND;VALUE=DATE-TIME:20171101T001500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1130@events01.synchrotron.org.au DESCRIPTION:Speakers: Stéphanie Szenknect (ICSM)\nMinerals belonging to t he monazite family\, REEPO4 (REE: Y\, Sc\, La to Dy) could incorporate in their structure substantial amounts of Th and U [1]. Moreover\, monazites maintain their crystallinity even after geological times of exposure to se lf-irradiation. Therefore\, this phase appears as a promising candidate fo r the specific conditioning of transuranic elements (AnIV\,AnIII). Already \, many thermodynamic properties of monazite are reported in the litteratu re [2]. However\, its hydrated form namely\, rhabdophane\, REEPO4.0.667 H2 O could be stabilized at low temperatures\, and thus control the concentra tions of actinides in solution after the leaching of the monazite matrices [3\, 4]. \n\nFor the first time\, a systematic study of the solubility of the rhabdophane\, LnPO4.0.667 H2O (Ln = La to Dy) was performed using ove r-saturated and under-saturated experiments at different temperatures (298 to 363 K) to demonstrate the reversibility of the solubility equilibrium [5]. The structure of the neoformed phases was carefully controlled in the entire range of temperatures in order to attribute unambiguously the solu bility products and the derived thermodynamic data associated to the rhabd ophane phases. The obtained results indicate that the stability domain of the rhabdophane phase is limited in temperature and depends on the ionic r adius of the lanthanide. The values of the solubility constant depend also slightly on the lanthanide with log KS\,0° (298 K) ranging from -25.6 ± 0.8 (Pr) to -24.9 ± 1.7 (Eu) with minimum values for Pr to Sm. The value s of the standard free enery of formation at 298 K varied between -1984 ± 2 and -2004 ± 2 kJ.mol-1 whatever the lanthanide element considered\, ex cept for Eu-rhabdophane that presented the highest value for the Gibbs ene rgy of formation (-1896 ± 2 kJ.mol-1).\nFrom the solubility data obtained at various temperatures\, the values of enthalpy of formation of the rhab dophanes were found between -2151 ± 13 and -2130 ± 12 kJ. mol-1 excepted for Eu for which it reached -2057 ± 9 kJ.mol-1. It is worth noting that the data reported by Ushakov et al. [6] for monazites LnPO4 (Ln = La to Gd ) determined by oxide melt calorimetry and recalculated by taking into acc ount the contribution of the water molecules are in very good agreement wi th the data obtained for rhabdophane in this work. This result indicates t hat the enthalpy of formation of the rhabdophane can be simply deduced fro m the enthalpy of formation of the monazite by adding the contribution of 0.667 molecule of structural water.\n\nThese results could be used to esti mate the thermodynamic properties of AnIIIPO4 .0.667 H2O (with AnIII =Am\, Pu or Cm) by analogy with the lanthanides of close ionic radii. The rhabd ophane structure can also incorporate AnIV by coupled substitution of LnII I by MII and AnIV. In this field\, Nd0.8Ca0.1Th0.1PO4 .n H2O were prepare d by wet chemistry route and preliminary solubility data were determined\, which showed that this phase is metastable in solution at 298 K\, Th and Nd being released leading to the formation of Th2(PO4)2(HPO4). H2O (TPHPH) [7] and NdPO4.0.667 H2O\, respectively.\n\nReferences:\n[1] N. Clavier\, R. Podor\, N. Dacheux\, (2011). Journal of the European Ceramic Society 31 : 941-976.\n[2] F. Poitrasson\, E. Oelkers\, J. Schott\, J.-M. Montel\, (2 004).Geochimica et Cosmochimica Acta 68: 2207-2221.\n[3] E. Du Fou de Kerd aniel\, N. Clavier\, N. Dacheux\, O. Terra\, R. Podor\, (2007). Journal of Nuclear Materials 362: 451-458.\n[4] N. Dacheux\, N. Clavier\, R. Podor\, (2013). American Mineralogist 98: 833-847.\n[5] C. Gausse\, S. Szenknect\ , D.W. Qin\, A. Mesbah\, N. Clavier\, S. Neumeier\, D. Bosbach\, N. Dacheu x\, (2016). European Journal of Inorganic Chemistry 2016: 4615-4630.\n[6] S.V. Ushakov\, K.B. Helean\, A. Navrotsky\, L.A. Boatner\, (2001). Journal of Materials Research 16: 2623-2633.\n[7] D. Qin\, C. Gausse\, S. Szenkne ct\, A. Mesbah\, N. Clavier\, N. Dacheux\, (2017). The Journal of Chemical Thermodynamics\, dx.doi.org/10.1016/j.jct.2017.01.003\n\nhttps://events01 .synchrotron.org.au/event/51/contributions/1130/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1130/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and characterisation of rare Ce3NbO7 compounds for use a s nuclear space batteries by neutron powder diffraction and X-ray absorpti on spectroscopy DTSTART;VALUE=DATE-TIME:20171031T223000Z DTEND;VALUE=DATE-TIME:20171031T224500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1125@events01.synchrotron.org.au DESCRIPTION:Speakers: Sean Barlow (University of Sheffield)\nCe3NbO7 weber ite-type materials\, an inactive analogue for Am3NbO7\, have potential use in americium radioisotope thermoelectric generators to be developed by th e European Space Agency for scientific missions beyond the orbit of Jupite r. Ceramics with greater than 97% purity were synthesised by thermal solid -state reaction and analytically characterised by X-ray diffraction\, neut ron diffraction\, helium pycnometry\, Raman spectroscopy and X-ray absorpt ion spectroscopy. The Magnetochemistry of the system was calculated with t he Weiss temperature and magnetic moment per unit volume derived\, in good agreement against the theoretical values. Reitveld refinement of neutron data was employed to identify the crystal structure of the novel cerium ni obate and determine the correct orthorhombic space grouping from either Cm cm (No.63) or Pnma (No.62) space groups. Ce3NbO7 refined well under both s ystems indicating possible pseudosymmetry. Cerium in the +III oxidation st ate was observed by X-ray absorption spectroscopy confirming the chemical speciation within the structure.\n\nhttps://events01.synchrotron.org.au/ev ent/51/contributions/1125/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1125/ END:VEVENT BEGIN:VEVENT SUMMARY:Efficient remediation of radiodine with silver-functionalized sili ca aerogel DTSTART;VALUE=DATE-TIME:20171101T041500Z DTEND;VALUE=DATE-TIME:20171101T044500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1122@events01.synchrotron.org.au DESCRIPTION:Speakers: Josef Matyas (Pacific Northwest National Laboratory) \nVarious volatile radionuclides are being released into gas streams and a queous solutions during reprocessing of used nuclear fuel and vitrificatio n of radioactive waste. Radioactive iodine-129 is of a particular concern because of its long half-life of 15.7 million years and the potential for biological processes to concentrate iodine. A number of materials are be ing developed worldwide to capture and immobilize iodine in a waste form o f a high chemical durability\; however\, none of them can be used as both a sorbent and a viable waste form. They can either encapsulate iodine-loa ded sorbent or sequester iodine that was removed from it. In the U.S.\, t he current benchmark for radioiodine capture is reduced silver mordenite ( AgZ) and that for the waste form is AgZ immobilized in a low-temperature g lass composite material. However\, the primary alternative option is a si lver-functionalized silica aerogel (Ag-aerogel). Ag-aerogel exhibits high capture efficiency (~ 500 mg/g) and selectivity for iodine (DF> 10000)\, and good resistance against aging in nuclear fuel reprocessing off-gas str eams. Its sorption performance is retained in deionized water and in a di lute salt solution with neutral pH containing iodide or iodate. A key adv antage of an Ag-aerogel is that\, after loading with iodine\, it can be co nsolidated into a dense and high-iodine-loaded silica-based waste form by simultaneous application of the heat and pressure. Presentation will disc uss the sorption performance of Ag-aerogel in different environments and p rovide an overview on the development of waste form.\n\nhttps://events01.s ynchrotron.org.au/event/51/contributions/1122/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1122/ END:VEVENT BEGIN:VEVENT SUMMARY:The development of zirconolite glass-ceramics for the immobilisati on of Pu-residues in the UK. DTSTART;VALUE=DATE-TIME:20171101T030000Z DTEND;VALUE=DATE-TIME:20171101T031500Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1120@events01.synchrotron.org.au DESCRIPTION:Speakers: Stephanie Thornber (University of Sheffield)\nThe UK has over 100 tonnes of separated PuO2 stored at the Sellafield site. The UK policy for managing this plutonium stockpile is to reuse this material as MOx fuel. However\, not all of the material is suitable for reuse and a proportion has been classified as higher activity waste. These plutonium wastes\, and any material which is not ultimately reused\, will require i mmobilization\, in a passively safe wasteform\, for long-term storage and eventual geological disposal. One proposed treatment plan is hot isostatic pressing of the plutonium waste / stockpile material\, with suitable prec ursors\, to form a glass-ceramic or full ceramic wasteform\, inside stainl ess steel canisters. Glass-ceramic materials are proposed for the low puri ty and highly variable wastes\, in which the glass phase provides wastefor m flexibility to accommodate impurities and variations in the waste feed c omposition. The plutonium partitions into the more durable ceramic phase\, zirconolite (CaZrTi2O7). Zirconolite has excellent wasteform properties i ncluding durability and radiation tolerance\, and readily accepts actinide s and rare earths into its crystal structure.\n\nIn this work\, the format ion of zirconolite is shown to depend sensitively on glass fraction and co mposition\, such that an Al rich glass promotes a higher yield of zirconol ite. The thermodynamic activity of Si in the system drives the crystalline phase assemblage\, by determining whether it is consumed in the amorphous glass phase or undesired accessory crystalline phases\, such as sphene (C aTiSiO5) and zircon (ZrSiO4). The design of an optimized glass-ceramic fo rmulation is demonstrated\, to maximize the yield of zirconolite and minim ise the yield of accessory phases. The partitioning of CeO2\, within the glass-ceramic wasteform\, as a PuO2 surrogate\, was studied using various charge compensation mechanisms\, under an imposed Fe/FeO and Ni/NiO buffer . Analysis by SEM/EDX\, XRD\, and Ce L3 edge XANES\, demonstrated reducti on of Ce(IV) to Ce(III) to favour incorporation of Ce within a perovskite accessory phase and the glass matrix. Ce partitioning in the zirconolite phase was maximized when retained as Ce(IV). These results demonstrate a feasible wasteform formulation for disposition of UK plutonium wastes and stockpile material.\n\nhttps://events01.synchrotron.org.au/event/51/contri butions/1120/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1120/ END:VEVENT BEGIN:VEVENT SUMMARY:Hot isostatic pressing of ion exchange materials\, from the Fukush ima and Sellafield sites\, to produce ceramic wasteforms. DTSTART;VALUE=DATE-TIME:20171031T213000Z DTEND;VALUE=DATE-TIME:20171031T220000Z DTSTAMP;VALUE=DATE-TIME:20260712T182538Z UID:indico-contribution-353-1111@events01.synchrotron.org.au DESCRIPTION:Speakers: Neil Hyatt (University of Sheffield)\nDecommissionin g and clean up of nuclear facilities requires the development of new techn ologies to condition radioactive wastes\, producing passively safe waste p ackages of minimal volume\, to reduce storage and disposal costs. We have applied hot isostatic pressing to demonstrate conceptual wasteforms for i on exchange materials and sludges present on the Sellafield site\, UK\, an d Fukushima site\, Japan. These radioactive wastes pose several challenge s which demand early conditioning to produce a passively safe wasteform\, including: i) the materials are of a wet and granular nature\, and hence d ispersible as a result of loss of containment\; ii) the materials are char acterised by very high dose rates as a result of their selectivity for sho rt lived radionuclides (e.g. Sr-90\, Cs-137\, Co-60)\; iii) the materials exhibit radiogenic self heating\, as a result of the concentration of such lived radio nuclides\; iv) the materials exhibit hydrogen production as a result of radiolysis of entrained water.\nIn this presentation we demonst rate the conversion of several commercial and natural inorganic ion exchan ge materials into multiphase ceramic wasteforms\, achieving a waste loadin g of 100 wt% and density in excess of 97% theoretical. High resolution th ermogravimetric analysis coupled with mass spectroscopy was utilised to ch aracterise the evolution of water and volatiles during the in-can bake out step\, prior to the HIP cycle. This allowed optimisation of the bake out parameters (temperature\, time and vacuum) to enable complete removal of water and volatiles\, affording ceramic bodies with minimal residual poros ity by hot isostatic pressing at 1250oC for 4h in stainless steel cans. Ch aracterisation of the ceramic wasteforms by SEM /EDX and X-ray diffraction revealed the nuclides of concern to be incorporated within well known nat ural mineral and synthetic phases\, with Sr partitioning into the SrTiO3 p ervoskite phase and Co\, Fe\, Mn and Cr partitioning into a spinel phase. Dynamic alteration experiments revealed matrix dissolution rates of less than 10-4 g m-2 d-1 under forward rate conditions at 90 oC.\nOverall\, hot isostatic pressing of inorganic ion exchange materials yields durable gla ss\, glass-ceramic\, and ceramic wasteforms\, with minimal voidage and por osity\, in which the radionuclide partitioning between glass and ceramic p hases can be controlled by wasteform composition and processing parameters . The resulting ceramic wasteforms are considered to meet the disposabili ty requirements of a UK Geological Disposal Facility for radioactive waste s.\n\nhttps://events01.synchrotron.org.au/event/51/contributions/1111/ LOCATION: URL:https://events01.synchrotron.org.au/event/51/contributions/1111/ END:VEVENT END:VCALENDAR