Browsing by Author "McGlinn, PJ"
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- ItemApplication of FEPs analysis to identify research priorities relevant to the safety case for an Australian radioactive waste facility(The American Society of Mechanical Engineers, 2007-09-02) Payne, TE; McGlinn, PJThe Australian Nuclear Science and Technology Organisation (ANSTO) has established a project to undertake research relevant to the safety case for the proposed Australian radioactive waste facility. This facility will comprise a store for intermediate level radioactive waste, and either a store or a near-surface repository for low-level waste. In order to identify the research priorities for this project, a structured analysis of the features, events and processes (FEPs) relevant to the performance of the facility was undertaken. This analysis was based on the list of 137 FEPs developed by the IAEA project on ‘Safety Assessment Methodologies for Near Surface Disposal Facilities’ (ISAM). A number of key research issues were identified, and some factors which differ in significance for the store, compared to the repository concept, were highlighted. For example, FEPs related to long-term ground-water transport of radionuclides are considered to be of less significance for a store than a repository. On the other hand, structural damage from severe weather, accident or human interference is more likely for a store. The FEPs analysis has enabled the scientific research skills required for the interdisciplinary project team to be specified. The outcomes of the research will eventually be utilised in developing the design, and assessing the performance, of the future facility. It is anticipated that a more detailed application of the FEPs methodology will be undertaken to develop the safety case for the proposed radioactive waste management facility. © 2007 The American Society of Mechanical Engineers
- ItemAppraisal of a cementitious material for waste disposal: neutron imaging studies of pore structure and sorptivity(Elsevier, 2010-08) McGlinn, PJ; de Beer, FC; Aldridge, LP; Radebe, MJ; Nshimirimana, R; Brew, DRM; Payne, TE; Olufson, KPCementitious materials are conventionally used in conditioning intermediate and low level radioactive waste. In this study a candidate cement-based wasteform has been investigated using neutron imaging to characterise the wasteform for disposal in a repository for radioactive materials. Imaging showed both the pore size distribution and the extent of the cracking that had occurred in the samples. The rate of the water penetration measured both by conventional sorptivity measurements and neutron imaging was greater than in pastes made from Ordinary Portland Cement. The ability of the cracks to distribute the water through the sample in a very short time was also evident. The study highlights the significant potential of neutron imaging in the investigation of cementitious materials. The technique has the advantage of visualising and measuring, non-destructively, material distribution within macroscopic samples and is particularly useful in defining movement of water through the cementitious materials. © 2010 Crown Copyright published by Elsevier Ltd.
- ItemAppraisal of a cementitious material for waste disposal: neutron imaging studies of pore structure and sorptivity(Laboratoire SUBATECH, 2008-10-14) McGlinn, PJ; de Beer, FC; Aldridge, LP; Radebe, MJ; Nshimirimana, R; Brew, DRM; Payne, TE; Olufson, KPTo characterise and to evaluate the durability, structural properties and sorptivity of a candidate wasteform for ILW and gain an understanding of the factors that control water movement through the matrix and the matrix and the resultant degradation process.
- ItemInterface phenomena in synroc, a titanate-based nuclear waste ceramic(Elsevier, 1995) Vance, ER; Ball, CJ; Blackford, MG; Day, RA; Lumpkin, GR; Smith, KL; Hart, KP; McGlinn, PJ; Thorogood, GJSeveral aspects of Synroc which fall into the broad class of interface phenomena are discussed. These are radiation damage processes which give rise to interfaces between damage tracks and neighbouring unirradiated material, intergranular films which have deleterious effects on chemical durability, and aqueous leaching of Synroc which takes place primarily at the interface between the solid and groundwater. © 1995 Elsevier B.V.
- ItemPartitioning and leaching behavior of actinides and rare earth elements in a zirconolite-bearing hydrothermal vein system(Cambridge University Press/Springer Nature, 2007) Payne, TE; Gieré, R; Hart, KP; Lumpkin, GR; McGlinn, PJChemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare earth elements (REE) in hydrothermal veins at Adamello, (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major elements (determined by extraction with 9M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases. Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconolite. The results show that REE and actinides present in chemically resistant minerals can be retained under aggressive leaching conditions. © 2007 Materials Research Society
- ItemPetrography and chemistry of tungsten-rich oxycalciobetafite in hydrothermal veins of the Adamello contact aureole, northern Italy(Springer Nature, 2017-09) Lumpkin, GR; Gieré, R; Williams, CT; McGlinn, PJ; Payne, TETungsten-rich oxycalciobetafite occurs in complex Ti-rich hydrothermal veins emplaced within dolomite marble in the contact aureole of the Adamello batholith, northern Italy, where it occurs as overgrowths on zirconolite. The betafite is weakly zoned and contains 29–34 wt% UO2. In terms of end-members, the betafite contains approximately 50 mol% CaUTi2O7 and is one of the closest known natural compositions to the pyrochlore phase proposed for use in titanate nuclear waste forms. Amorphization and volume expansion of the betafite caused cracks to form in the enclosing silicate mineral grains. Backscattered electron images reveal that betafite was subsequently altered along crystal rims, particularly near the cracks. Electron probe microanalyses reveal little difference in composition between altered and unaltered areas, except for lower totals, suggesting that alteration is primarily due to hydration. Zirconolite contains up to 18 wt% ThO2 and 24 wt% UO2, and exhibits strong compositional zoning, but no internal cracking due to differential (and anisotropic) volume expansion and no visible alteration. The available evidence demonstrates that both oxycalciobetafite and zirconolite retained actinides for approximately 40 million years after the final stage of vein formation. During this time, oxycalciobetafite and zirconolite accumulated a total alpha-decay dose of 3.0–3.6 × 1016 and 0.2–2.0 × 1016 α/mg, respectively. © 2024 Springer Nature
- ItemPhysical stability and durability of heavy-ion irradiated crystalline zirconolite CaZrTh2O7 ceramic designed for minor actinide disposition(Commissariat à l'énergie atomique (CEA), 2004-07-01) Advocat, T; McGlinn, PJ; Smith, KL; Gosset, D; Rabiller, H; Zhang, ZM; Lumpkin, GR; Chaumont, JExternal irradiation studies with heavy ions Pb3+ accelerated at 510 keV were conducted on non radioactive zirconolite ceramic pellets, containing actinide surrogates such as Rare Earth Elements (REE). Ion irradiation of ceramic pellet surfaces has transformed the outermost several tenths of nanometers of the surface into a metamict state. The chemical durability in water of the irradiated zirconolite ceramics was measured at 100 deg C. The dissolution behavior is similar to that for the fully crystalline materials, and natural zirconolite minerals as well, which are at least several hundred million years old and self-irradiated up to 10 20}alpha decay/g due to the presence of appreciable quantities of Th and U. The amorphization process of the crystalline structure by the alpha decay does not modify the high chemical durability of zirconolite.
- ItemPrediction of the long-term performance of crystalline nuclear waste form phases from studies of mineral analogues(Institution of Engineers, Australia, 1994-05-01) Lumpkin, GR; Smith, KL; Blackford, MG; McGlinn, PJ; Gieré, R; Williams, CTThis investigation outlines the use of natural analogues as a means of assessing the long-term performance of actinide host phases in crystalline nuclear waste forms. We employed several analytical techniques to study the mineral zirconolite, an important actinide host phase in Synroc and tailored ceramics. The following conclusions were reached: 1) Natural zirconolite experiences a crystalline to aperiodic transformation at doses of approximately 10 to 10 alpha/mg (0.08-1.0 dpa), consistent with the results of accelerated damage testing on synthetic zirconolite. 2) Damage microstructures are consistent with the accumulation and overlap of alpha-recoil collision cascades, resulting in aperiodic domains which increase in volume as a function of dose. 3) There is evidence for long-term annealing of alpha-recoil damage in zirconolite at a rate 2-5 times slower than in the structurally related mineral pyrochlore. 4) Analysis of data from the only documented natural zirconolites to show hydrothermal alteration [resulting from F- and P-rich aqueous fluids at T = 500-600 degrees C and P = 2 kb, Giere and Williams (14)], suggests that Th and U were released to the fluid phase. 5) The effects of low temperature alteration of radiation damaged zirconolite by a Si-rich ground water or fluid phase were identified in the oldest (2.5 x 10 yr) sample in our research collection. Alteration involved incorporation of Si along microfractures at the expense of Ca, Ti, and Fe, but Th and U remained immobile. In this same sample, there is evidence for migration of at least 50% of the radiogenic Pb from both unaltered and altered areas of zirconolite. Most of the Pb may have been retained within the sample as fine precipitates of galena (PbS).
- ItemA report to NERDDP on project no. 1319 entitled : description of synroc durability: kinetics and mechanisms of reaction(Australian Nuclear Science and Technology Organisation, 1990-08) Jostsons, A; Smith, KL; Blackford, MG; Hart, KP; Lumpkin, GR; McGlinn, PJ; Myhra, S; Netting, A; Pham, DK; Smart, RStC; Turner, PSThis is the technical report to NERDDP on Project 1313, "Description of Synroc Durability: Kinetics and Mechanisms of Reaction". Many physical and chemical processes occur, slightly and concurrently, when Synroc is exposed to leachants. A few of these include: * ion-exchange between Synroc and the leachant; * dissolution of some primary phases; * formation of colloids; * precipitation of secondary phases. All of these processes (and others) affect the durability of Synroc. Consequently, it has been necessary to apply an armoury of techniques, to unravel the various processes and their effects. Techniques used include: * solution analysis by inductivity coupled plasma mass spectrometry (ICP/MS) and inductivity coupled plasma optional emission spectroscopy (ICP/OES); * scanning and analytical transmissions electron microscopy (SEM and AEM respectively); * X-ray photoelectron spectroscopy (XPS) and Auger spectroscopy. We have matched or exceeded all the sub-objectives agreed to and funded by NERDDP in 1989/90. Furthermore we have begun to integrate the information generated under the auspices of the grant as well as information subsequently collected, into a comprehensive model. The information contained within the bulk of this report can be broken down into areas which relate to the sub-objectives of the project.
- ItemRetention of actinides in natural pyrochlores and zirconolites(De Gruyter, 1994-12-01) Lumpkin, GR; Hart, KP; McGlinn, PJ; Payne, TENatural pyrochlore and zirconolite undergo a crystalline-aperiodic transformation caused by alpha-decay of 232Th and 238U at dose levels between 2X1014 and 3X1017 α/mg. The principal effects of the transformation are volume expansion and micro-fracturing, providing potential pathways for fluids. Geochemical alteration of the minerals may occur under hydrothermal conditions or in low temperature, near surface environments, but Th and U usually remain immobile and can be retained for time scales up to 10 9 years. However, the Th-U isotope systematics of a zirconolite-bearing vein and dolomite host rock may provide evidence for disequilibrium between 230Th, 234U and 238U. © 1994 R. Oldenbourg Verlag, München
- ItemWater transport through cement-based barriers - a preliminary study using neutron radiography and tomography(Elsevier, 2009-06-21) Brew, DRM; de Beer, FC; Radebe, MJ; Nshimirimana, R; McGlinn, PJ; Aldridge, LP; Payne, TEIn this preliminary study we use neutron radiography and tomography to examine differences in water transport through cement pastes and mortars. Bulk residual water contents and sorptivity curves determined using neutron radiography are compared with data obtained gravimetrically. In addition, macro-pore volume distributions of each sample were measured. Furthermore, it was possible to use neutron radiography to monitor the change in the mass of water when samples were dried or when water moved into the samples. The trends and absolute values of weight loss and gain obtained using both approaches are very consistent for mortars, especially when a neutron-scattering correction is applied. © 2009, Elsevier Ltd.