Conference Publications

Browse

Now showing 1 - 5 of 2564

Efficiency enhancements to Monte Carlo simulation of heavy ion elastic recoil detection analysis spectra
(Elsevier, 2002-05) Franich, RD; Johnston, PN; Bubb, IF; Dytlewski, N; Cohen, DD
Monte Carlo (MC) simulation can be used to simulate heavy ion elastic recoil detection analysis spectra, including the broadening and tailing effects of multiple and plural scattering, although it is very costly in terms of computer time. In this work, kinematic relationships and experimental parameters are exploited to implement efficiency improvements in the MC modeling process. For thin films, incident ions that pass through the sample without undergoing a significant scattering event need not be tracked. Ions that might generate a detectable scattered or recoiled ion are predicted by generating, in advance, the impact parameters which will define its path. Light recoiled target atoms may be dealt with in the same way. For heavy atoms, however, the probability of large angle scattering events is so high that the paths of most recoil atoms are dominated by several scattering events with large angular deflections. © 2002 Published by Elsevier Science B.V.
To leave or not to leave: a tiered assessment of the impacts of scale residue from decommissioned offshore oil and gas infrastructure in Australia
(ICRP, 2025-11-06) MacIntosh, A; Cresswell, T; Koppel, DJ; Hirth, GA; Tinker, R; Dafforn, KA; Chariton, AA; Penrose, B; Langendam, AD
There are a range of potential options for the decommissioning of offshore petroleum infrastructure, including: complete removal; removal of topside infrastructure with subsea infrastructure left in situ; or partial removal or modification of infrastructure. The current decommissioning liability in Australia is estimated to exceed US$40 billion over the next 50 years. This is founded on the base-case regulatory position of complete removal of all infrastructure, with over half the liability occurring in the next 10 years. In Australia, a recently updated decommissioning framework requires that the planning for decommissioning begins from the outset of the project, and plans are matured throughout the life of operations. Successful decommissioning of subsea oil and gas infrastructure requires an effective and safe approach for assessing and managing chemical and radiological residues. Naturally occurring radioactive materials (NORM) are ubiquitous in oil and gas reservoirs around the world and may form contamination products including scales and sludges in topside and subsea infrastructure. In situ decommissioning of infrastructure left in the marine environment has many ecological benefits including establishment of artificial reefs, economic benefits from associated fisheries, reduced costs and improved human safety outcomes. However, there may be ecological risks associated with leaving infrastructures in the marine environment that are not well understood. Following a scenario of in situ decommissioning of subsea petroleum infrastructure, marine organisms occupying the exteriors or interiors of production pipelines may have close contact with the scale (metal and radionuclide contaminants). Consequently, radio- and chemo-toxicological effects from the scale could occur respectively. This paper considers the current assessment process for NORM-contamination products in oil and gas systems, recent and emerging Australian research in marine radioecology. Here we demonstrate a tiered approach to assess the ecological impacts of pipeline scale related to decommissioning practices, and identifies key research priorities. This can further aid our understanding of the fate of NORM contaminates in subsea oil and gas systems and guide Australia-specific (expand to other petroleum operating countries) risk assessments for infrastructure decommissioning options. The creation of a tiered assessment will enable industry to optimise decommissioning solutions and allow regulators to set clearer expectations on the requirements for environmental protection.
Radionuclide uptake mechanisms by native flora in the vicinity of uranium mines in arid South Australia
(ICRP, 2019-11-17) Pandelus, SB; Pring, A; Johansen, MP; Payne, TE; Stopic, A; Spooner, NA; Kalnins, GAG; Popelka-Filcoff, RS
Environmental risk assessments for radiological impacts follow internationally accepted methods including use of the Environmental Risk from Ionising Contaminants: Assessment and Management (ERICA) tool. Concentration ratios (ratio of radionuclides in an organism to that of its host soil/water- CR) are an essential input for these models. However, the available international input data are primarily from temperate Europe and North America, and may not apply in arid conditions. Previous studies have shown that Australian native species accumulate radionuclides from their environment differently when compared to similar species from other climates. This research aims to develop a concentration ratio dataset relevant for U and Th series radionuclides in arid and semi-arid conditions. Olympic Dam, operated by BHP, is a large copper, uranium, gold and silver producer in South Australia, and utilises underground mining, with the ore being processed on site. To examine radionuclide uptake mechanisms by native flora, samples of flora and adjacent soil have been collected at Olympic Dam. Analyses of flora and soil samples included gamma-ray spectroscopy, neutron activation analysis, alpha-particle spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS). Alternative analytical methods have been incorporated including alpha track analysis for flora samples. Alpha track analysis uses a nuclear emulsion gel layer applied to the individual leaf sample. Analysis of the gel is used to identify radionuclide accumulation and spatially-resolve its location within structures of the leaves. Soil from the surface to 10 cm below the surface was analysed by ICP-MS. Results show a gradient of uranium concentration from 4 ppm at the surface to 0.5 ppm at a depth of 10 cm. The soil depth profile data show that the most probable mechanism of radionuclide transport is airborne and therefore any potential uptake into flora is influenced by the depositional effects on the soil surface. Overall this research provides a better understanding of the behaviour of radionuclides in an arid environment and provides data on the mechanisms of radionuclide uptake in flora. It augments existing international data for use in models in Australia and other localities with similar arid environments.
The interpretation of archaeological dates from an AMS perspective
(University of Auckland, 2001-02-05) Zoppi, U; Sagona, A; Siegele, R; Hua, Q; Jacobsen, GE; Lawson, EM
The XVII century saw the establishment of the scientific method and scholars such as Galileo were giving excellent contributions to a variety of fields ranging from the natural sciences to the humanities. At the dawn of the new millenium, after a period of excessive specialization, the scientific climate is once again encouraging broad collaborations across different disciplines. For projects involving AMS measurements in general and radiocarbon dating in particular, the benefits of this new trend are numerous. For example, the full potential of the radiocarbon dating method can be exploited only through the mutual understanding of the problems related to sample selection, chemical preparation, AMS measurement, data analysis and interpretation. This paper is intended to enhance the exchange of information by reporting to our current and potential collaborators about the latest technical developments undertaken at the ANTARES AMS facility at ANSTO. Furthermore, we will present two splendid examples of collaborative research: the radiocarbon dating of a replica of a famous chesspiece and the archaeological investigations at the ancient settlement of Sos Hoyuk (north-eastern Anatolia, Turkey) where the multidisciplinary approach was the key to a better understanding of the social structure, settlement patterns, land use and cultural contact, especially with the lands of Trans-Caucasus. © The Authors
Radiolytic stability of metal (IV) phosphonate sorbents designed for minor actinide-lanthanide separations
(CEA, 2024-09-01) Cataldo, T; Veliscek-Carolan, J; Bedford, NM; Le Caër, S
Nuclear power is an intrinsically clean source of energy. However, improvements in nuclear waste treatment are required. The minor actinide (MA) elements in nuclear waste are problematic due to their radiotoxicity and long half-lives. In principle, minor actinides (MAs) in nuclear waste could be recycled. However, the chemical similarity of MAs and the lanthanide fission products also found in nuclear waste means that separating and recycling MAs is extremely challenging. Hence, there is a need for materials that can selectively separate MAs from lanthanides in nuclear waste, whilst also possessing the necessary acid and radiation resistance required to function in nuclear waste conditions. Metal (IV) phosphonates, such as titanium or zirconium phosphonates, are a type of material with promising potential for MA-lanthanide separation applications. Metal phosphonates are a coordination polymer: a material in which inorganic metal cations are structurally joined together by organic ligands via coordinate bonds. The hybrid inorganic-organic nature of metal phosphonates allows for a variety of chemical and physical properties. In the context of MA-lanthanide separations, the phosphonate component allows for the intramolecular incorporation of organic ligands that provide selectivity and efficiency for MA sorption. Furthermore, the strong M(IV)–O–P bonding of the inorganic component provides stability and resistance to acid and radiation damage. Post-synthesis, metal phosphonates are collected as a porous, solid powder; hence, they can be employed as a solid-phase phase sorbent in MA-lanthanide separations. Previous studies on zirconium (IV) phosphonate materials have demonstrated promising sorption capacity, selectivity for MA over lanthanides, and excellent stability1,2,3. Therefore, further study and optimization of these materials presents a potential pathway for solving the challenges of MA separation and recycling. In this study, a zirconium phosphonate sorbent that intramolecularly incorporates the MA-selective 2,6-bis(1,2,3-triazol-4-yl)pyridine (PTP) ligand was synthesised. The sorbent (ZrPTP) was irradiated with high energy electron radiation to doses of 2 MGy to study its radiation stability. Since ZrPs are highly amorphous, synchrotron light sources were employed to accurately assess the average local structure before and after irradiation using x-ray absorption spectroscopy (XAS) and atomic pair distribution function (PDF). Gas chromatography, solid-state NMR and infrared spectroscopy were also used to support the characterisation. Lastly, the MA-selectivity of ZrPTP before and after irradiation was compared using americium and europium. It was found that ZrPTP possessed excellent radiation stability for doses up to 2 MGy. Characterisation of ZrPTP exhibited only small amounts of radiation damage to its Zr-O bonds, aliphatic C-H bonds, and its N bonds in the triazole groups. Furthermore, ZrPTP demonstrated maintained selectivity for americium over europium even after a 2 MGy dose. Overall, the results extensively demonstrate the viability of metal phosphonate sorbents for nuclear waste treatment applications in terms of their radiation stability. © The Authors

Browse

Recent Submissions