Browsing by Author "Vine, M"

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    Analytical method development for tritium in tree transpirate from the Little Forest Burial Ground
    (Australian Nuclear Science and Technology Organisation, 2009-08) Twining, JR; Harrison, JJ; Vine, M; Creighton, NM; Neklapilova, B; Hoffmann, EL
    The Little Forest Burial Ground (LFBG) is a near-surface low-level nuclear waste repository located within the buffer zone surrounding the Lucas Heights Research Laboratories of ANSTO (Figure 1). Tritium (3H, ‘T’), as tritiated water (HTO), was one of the radioactive substances placed into the trenches located within the LFBG (Isaacs and Mears, 1977). This material will behave conservatively in regard to any seepage from the site of deposition. As such, it should be a good indicator of groundwater movement at the site. Water is a vital requirement of plants. Hence, it was proposed that samples from herbs and trees may be useful to assess the biologically available HTO and also provide an indication of a potential exposure for environmental dose assessment, not only for 3H but also for the other radionuclides potentially migrating with the water from the trenches. As part of the initial draft plan for a vegetation survey in the LFBG (Twining and Creighton, 2007) the following two null hypotheses were established: H0a that there is no significantly higher concentration of specific contaminants in foliage of trees growing over, or adjacent to, the pits than there is in the foliage of the same species growing away from the pits; H0b that there is no correlation between contaminant levels in the seepage plume and surface vegetation. These hypotheses are to be tested using the acquired data. However, as part of the process of applying HTO in transpirate as a monitoring tool, some method development has been required. This report covers all aspects of that development and provides a recommended approach to acquiring such data and recording the information.
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    Identification of sources and processes in a low-level radioactive waste site adjacent to landfills: groundwater hydrogeochemistry and isotopes
    (Taylor & Francis Group, 2014-11-25) Cendón, DI; Hughes, CE; Harrison, JJ; Hankin, SI; Johansen, MP; Payne, TE; Wong, HKY; Rowling, B; Vine, M; Wilsher, KL; Guinea, A; Thiruvoth, S
    Multiple tracer-element and isotope approaches were applied at a 1960s-era low-level radioactive waste burial site located in the Lucas Heights area on the southwest urban fringe of Sydney, Australia. The site is situated among other municipal and industrial (solid and liquid) waste disposal sites causing potential mixing of leachates. Local rainfall contains marine-derived major ion ratios that are modified during infiltration depending on waste interactions. The local geology favours the retention of contaminants by ion-exchange processes within the clay-rich soils and the shale layer underlying the burial site. Local soils experience periodic infiltration and wetting fronts that can fully saturate the waste trenches (bathtub effect) while surrounding soils are mostly unsaturated with discontinuous perched lenses. Within the trenches, the degradation of organic matter results in localised methanogenesis, as suggested by enriched δ2H and δ13CDIC values in adjacent subsurface water. Movement of contaminants from the trenches is indicated by Na+, Br? and I? concentrations, variations in 87Sr/86Sr, enriched δ13CDIC values and evolution of δ34S of dissolved sulfate in perched water bodies above the shale. Although transport is limited by the low transmissivity of the clay-rich soils, migration and mixing processes are indicated by the variation of concentrations with distance from the trenches, disappearance of δ2H enrichments, mixing with other sources of Sr and sulfate isotope fractionations. The depth distribution of waste-derived contaminants (specifically 3H and Be) between the perched water surrounding the trenches, and the underlying shale and sandstone layers, indicates limited downward transport of contaminants. Past removal of the shale layer in an adjacent site, Harrington's Quarry, has facilitated the mixing of some municipal waste leachates (characterised by circum-neutral pH, high alkalinity, low sulfate, high 3H, high Be, enriched δ2H and δ13CDIC) into the underlying groundwater system as suggested by high TDS, Cl?/Br? ratios, Be and 3H found in deeper wells. This study demonstrates the applicability of using trace elements, stable- and radio-isotopes to document the existing geochemistry and the contaminant transport from the waste trenches. The multiple tracer approach addresses the complexities of transport at the site and differentiates various municipal, industrial and radioactive waste sources. © 2014 Informa UK Limited
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    Method development for tritium measurements and initial evaluation of tritium data for tree transpirate from a legacy waste site in eastern Australia
    (South Pacific Radioactivity Association, 2008-11-25) Twining, JR; Creighton, NM; Harrison, JJ; Hoffmann, EL; Neklapilova, B; Vine, M
    Tritium (3H), as tritiated water, was one of the radioactive substances placed into the trenches located within the former waste disposal site known as the Little Forest Burial Ground (LFBG). This site is located in the 1.6 km exclusion zone surrounding ANSTO the previous research reactor, HIFAR, south of Sydney. Tritium will behave conservatively in regard to any seepage from the site of deposition, and therefore should be a good indicator of groundwater movement at the site. Water is also a vital requirement of plants on the site. Hence, it was proposed that analysis of the tritium content of shrubs and trees may be a useful means to assess and access the biologically available 3H. In addition, it should provide an indication of potential exposure for environmental dose assessment, not only for 3H but also for the other radionuclides potentially migrating with the water from the trenches. To test these ideas, sampling of tree transpirate at LFBG has been initiated. In order to utilise measurements of 3H in transpirate as a monitoring tool, some method development has been required. Relatively small sample volumes have required atypical preparation methods and sample quenching has been an issue. There is also a need to consider background concentrations, given that the HIFAR reactor at the Lucas Heights Research Reactor has emitted 3H to the local environment for several decades. Results of sampling and analysis since July 2007 Will be presented and each of these issues will discussed in this initial report.
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    Movement of a tritium plume in shallow groundwater at a legacy low level radioactive waste disposal site in eastern Australia
    (Elsevier, 2011-10-01) Hughes, CE; Cendón, DI; Harrison, JJ; Hankin, SI; Johansen, MP; Payne, TE; Vine, M; Collins, RN; Hoffmann, EL; Loosz, T
    Between 1960 and 1968 low-level radioactive waste was buried in a series of shallow trenches near theLucas Heights facility, south of Sydney, Australia. Groundwater monitoring carried out since the mid1970s indicates that with the exception of tritium, no radioactivity above typical background levels hasbeen detected outside the immediate vicinity of the trenches. The maximum tritium level detected ingroundwater was 390 kBq/L and the median value was 5400 Bq/L, decay corrected to the time ofdisposal. Since 1968, a plume of tritiated water has migrated from the disposal trenches and extends atleast 100 m from the source area. Tritium in rainfall is negligible, however leachate from an adjacentlandfill represents a significant additional tritium source. Study data indicate variation in concentrationlevels and plume distribution in response to wet and dry climatic periods and have been used todetermine pathways for tritium migration through the subsurface.Crown Copyright © 2010 Published by Elsevier Ltd
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    Movement of a tritium plume in shallow groundwater at a legacy low-level radioactive waste disposal site in eastern Australia over four decades
    (South Pacific Radioactivity Association, 2008-11-23) Hughes, CE; Cendón, DI; Collins, RN; Hankin, SI; Harrison, JJ; Hoffmann, EL; Loosz, T; Payne, TE; Pham, AN; Twining, JR; Vine, M; Waite, TD
    Between 1960 and 1968 radioactive Wastes with low levels of activity were buried by the Australian Atomic Energy Commission in a series of shallow trenches in bushland near the Lucas Heights facility, on the outskirts of Sydney. Groundwater monitoring carried out since the mid 1970’s has found that no radioactivity, with the exception of tritium, has been detected outside the immediate vicinity of the trenches. However, over this period of more than 40 years, a plume of tritiated water has migrated om the trenched area and extends at least 100 m from the source. The peak tritium activity detected in the mid l970’s was 390 kBq/L directly adjacent to the trenches. Modem tritium activity in the groundwater is less than the drinking water standard of 7.6 kBq/L and poses no radiological risk to the community or local environment. The tritium dataset will be presented and analysed to determine the effects of rainfall and drought periods on tritium levels and plume transport.
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    Using hydro-geochemistry and isotopes to trace groundwater flow from Little Forest Burial Ground and surrounding landfills
    (Australian Nuclear Science and Technology Organisation, 2012-10-16) Cendón, DI; Hughes, CE; Harrison, JJ; Hanklin, SI; Johansen, MP; Payne, TE; Wong, HKY; Rowling, B; Vine, M; Wilsher, KL; Guinea, A; Thiruvoth, S
    Multiple tracer-element and isotope approaches were used to study groundwater near a legacy low-level radioactive waste burial site surrounded by municipal and industrial waste sites. The interaction of rainfall, with its marine-derived major ion ratios, and waste from the sites is apparent, however, clay-rich soils and shale at the site tend to retain many contaminants via ion exchange and other processes. High permeability of the disposal trenches provides a pathway for groundwater recharge, with discontinuous perched groundwater lenses found in their vicinity. Within the trenches, the degradation of organic matter results in localised methanogenesis, as suggested by enriched δ2H and δ13CDIC in adjacent subsurface water. Movement of contaminants from the waste sites is indicated by Na+, Brˉ and Iˉ concentrations, variations in 87Sr/86Sr, enriched δ13CDIC and evolution of δ34S of dissolved sulfate in perched water bodies above the shale. There is clear evidence of a tritium plume from the LFBG trenches, although the adjacent landfills provide an additional tritium source. Waste burial records show that over 1000 kg of Be (mostly BeO) were disposed in the LFBG trenches. However, beryllium concentrations in groundwaters near the trenches are quite low, and appear more likely to be controlled by the host lithologies and the other sources of contamination in the vicinity, rather than by leaching of Be from the LFBG waste. Past removal of the shale layer in an adjacent site, Harrington’s Quarry, has led to the mixing of municipal waste leachates into the underlying groundwater system as suggested by high TDS, Cl−/Br− ratios, Be, and 3H found in deeper wells. The multiple tracer approach addresses the complexities of transport at the site and differentiates various municipal, industrial, and radioactive waste sources