Little Forest legacy site - summary of site history until the commencement of waste disposal in 1960

The Australian Atomic Energy Commission (AAEC) disposed of low-level radioactive waste at a site in the Little Forest area on the southern periphery of Sydney between 1960 and 1968. Following common practice of the period, a clay-rich site was selected in the vicinity of the AAEC’s facility at Lucas Heights, and waste was mainly disposed by burial in closely spaced unlined trenches. During the time of operations (and subsequently until 2014), the site was known as the ‘Little Forest Burial Ground’ (LFBG). In recent years, ANSTO has been implementing a detailed scientific study of the status of the disposal site, now referred to as the Little Forest Legacy Site (LFLS). This study includes sampling of vegetation, groundwater and soils. As part of the research, documents related to the disposal operations have been reviewed, as well as information and data from over 40 years of monitoring and studies of the LFLS. During these investigations, it has become clear that although numerous records have been preserved, there are nevertheless some key information gaps. Furthermore, while there is evidence of several previous attempts to summarise the material, none of these has led to a definitive summary of the history of the site and disposal activities. The present report aims to summarise the history of the site until the commencement of disposal operations in 1960. This document contains information on the technical justification and other factors involved in the selection of the site, and some comments on the site selection process are presented in the final section. The main objective of this report is to provide a record of the events during this period, which will assist in understanding the disposal operations at the site and provide a context for interpreting subsequent monitoring data

Background report on the Little Forest Burial Ground legacy waste site

The Australian Atomic Energy Commission (AAEC) buried low-level radioactive waste at the Little Forest Burial Ground (LFBG) near Lucas Heights between 1960 and 1968. The disposal site has since been under a constant care, maintenance and routine monitoring regime by the AAEC and its successor, the Australian Nuclear Science and Technology Organisation (ANSTO). The routine environmental measurements at the site have been reported in ANSTO’s series of monitoring reports. ANSTO has commenced a detailed scientific study of the status of the site, including sampling of vegetation, groundwater and soils. The project has undertaken soil coring, geophysical surveys and installation of groundwater sampling bores. The research applies advanced analytical techniques, such as accelerator mass spectrometry, which have not been employed in the analysis of environmental samples from the LFBG in the past. Project personnel are reviewing documents related to the disposal operations, as well as information and data from over 40 years of monitoring and investigation of the LFBG. In addition to relatively shortlived radionuclides, such as 60Co, 137Cs and 90Sr, the site contains both nonradioactive toxic contaminants (including more than 1000 kg of beryllium) and longlived alpha-emitting radionuclides including plutonium, uranium and thorium. Over the period since operations ceased, a plume of tritium in groundwater has developed and there has been intermittent subsidence of the soil covering the trenches. This subsidence is attributed to voids developing in the buried wastes, due to deterioration of containers and disposed objects. Contamination of the ground surface with radionuclides has been documented in some AAEC reports. The data obtained by the research project at LFBG will enable the assessment of possible management options including continuing the current regime of maintenance and monitoring, in-situ remediation, or exhumation. Unless the site is remediated, it will require some form of institutional control in perpetuity, due to the presence of beryllium and long-lived actinides. The present report provides an overview of the disposal operations at LFBG, briefly reviews previous reports and describes current ANSTO research activities at the site

Adsorption of a jet fuel on a model organic-clay soil: application of small angle neutron scattering.

Small angle neutron scattering (SANS) data are reported from a system that models the contamination of a clay/organic matter soil from a fuel spillage. The soil was represented as an aqueous dispersion of the synthetic clay mineral Laponite coated with lysine, and the contaminant was a representative jet fuel, quadricyclane, mixed with the detergent cetyltrimethylammonium bromide (CTAB). The adsorbed surface coverage on the clay was estimated. It is shown that the presence of adsorbed lysine considerably enhances the subsequent adsorption of both CTAB and quadricyclane. It is demonstrated that the SANS technique can contribute to the general problem of environmental remediation and retention by probing the interactions of pollutants and clay surfaces. © 2008, National Research Council Canad

Kinetics of coupled Fe(II)-catalysed ferrihydrite transformation and U(VI) reduction

Antimony is released into the environment in some natural and man-induced processes. [1]. Yet, its impact on the transformation processes of heavy metal-adsorbing minerals remains poorly understood. In acid-mine drainage systems and shooting ranges, the adsorption of antimony by iron oxides such as ferrihydrite can play a major role. The poorly crystalline 2-line ferrihydrite represents one of the most common Fe oxides in these settings and can transform to goethite (,-FeOOH) or hematite (,-Fe2O3) with time [2]. The rate of transformation depends on the pH, temperature, and on the ions and molecules present during the transformation process [3]. This study focuses on the transformation of synthetic ferrihydrite to crystalline iron oxides in the presence of Sb(V). Transformations were carried out for 1-16 days at 70 ºC and at pH 4, 7 and 12, with different concentrations of Sb(V) (0.00, 0.23, 0.75, 2.25 and 6.00 mM Sb). Samples taken from aqueous suspensions were washed, dried, and characterized by X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS). At pH 12, goethite (Sb concentrations up to 3.7 mg Sb/g) is favored and the transformation is completed after one day. Only a concentration of 6 mM Sb retarded the transformation, where even after 8 days only 50 % of the ferrihydrite was transformed into goethite. Transformations at pH 7 led to a mixture of 75 % hematite and 25 % goethite (4.3 mg Sb/g). However, at concentrations of 6 mM Sb, feroxyhyte (!- FeOOH) (9.1 mg Sb/g) was favored instead. At pH 4, hematite (32.3 mg Sb/g) was favored except for concentrations of 6 mM Sb, were again feroxyhyte (141.1 mg Sb/g) occurred. We assume that increased Sb concentrations favor feroxyhyte and indicate the incorporation of Sb into the structure of feroxyhyte. © The Author

Ferric iron geometry and coordination during hydrolysis and ferrihydrite precipitation

Definitive structural characterisation of ferrihydrite has challenged scientists primarily due to its nanosized particles and inherent long-range structural disorder which challenges analytical methodology (and modelling) typically employed to determine the structure of minerals. Here we report on the application of a synchrotron quick-scanning X-ray absorption spectroscopy (XAS) approach, which allows the collection of Extended X-ray Absorption Fine Structure (EXAFS) spectral data to k = 15 Å-1 in < 1 minute, to obtain unparalleled iron Kedge data on the hydrolysis of FeIII(H2O)6 and ferrihydrite precipitation. Modelling of the pre-edge and EXAFS data: 1) supports theoretical studies which have suggested the existence of a monomeric penta-coordinated FeIII hydrolysis species and; 2) corroborates recently proposed structural models of ferrihydrite that contain tetrahedral FeIII. Modelling results indicate that ferrihydrite consists of 15 to 25 % tetrahedral FeIII and suggest that this geometry must be included in any comprehensive structural model of ferrihydrite and, furthermore, should be considered when evaluating the reactivity, stability and other structure-property relationships of this mineral. © The Authors

Accumulation of plutonium in mammalian wildlife tissues: comparison of recent data with the ICRP distribution models

We examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife to address the paucity of such data under environmental exposure conditions. Pu activity concentrations were measured in Macropus rufus (red kangaroo), Oryctolagus cuniculus (European rabbit), and Pseudomys hermannsburgensis (sandy inland mouse)inhabiting the relatively undisturbed, semi-arid conditions at the former Taranaki weapons test site at Maralinga, Australia. Of the absorbed Pu (distributed via circulatory and lymph systems) accumulation was foremost in bone (83% ±10% SD), followed by muscle (9% ±10%), liver (7% ±7%), kidneys (0.5% ±0.3%), and heart (0.4% ±0.4%). The bone values are higher than those reported in ICRP 19 and 48 (45-50% bone), while the liver values are lower than ICRP values (30-45% liver). The ICRP values were based on data dominated by relatively soluble forms of Pu, including prepared solutions and single-atom ions produced by decay following the volatilisation of uranium during nuclear detonation (fallout Pu, ICRP 1986). In contrast, the Maralinga data relates to low-soluble forms of Pu used in tests designed to simulate accidental release and dispersal. We measured Pu in lung, GI-tract and the skin and fur as distinct from the absorbed Pu in bone, liver, muscle, and kidneys. Compared with the mean absorbed activity concentrations, the results for lung tissues were higher by up to one order of magnitude, and those in the GI tract contents and the washed skin/fur were higher by more than two orders of magnitude. These elevated levels are consistent with the presence of low-soluble Pu, including particulate forms, which pass through, or adhere upon, certain organs, but are not readily absorbed into the bloodstream. This more transitory Pu can provide dose to the lung and GI tract organs, as well as provide potential transfer of contamination when consumed in predator-prey food chains, or during human foodstuff consumption. For example, activity concentrations in O. cuniculus edible samples prepared according to traditional aboriginal methods were more than two orders of magnitude higher than in muscle alone. The increase was due to inclusion of GI tract components and contents in the traditional method. Our results provide new insights into the sequestration of Pu in mammalian tissues under environmental exposure conditions. These results contrast with those related to the specific forms of Pu and exposure conditions upon which the ICRP models were based. However, they provide data relevant to the assessment of key environmental legacy waste sites, and of potential release scenarios for the low-soluble oxide forms in the growing worldwide inventory of Pu associated with power production

Polarimetric observations of OH masers in proto-planetary nebulae

The 1612 and 1667 MHz OH maser lines have been measured in all four Stokes parameters in 47 proto-planetary nebula (PPN) candidates. Out of 42 objects detected, 40 and 34 are 1612 and 1667 MHz emitters, respectively. The spectral extent of the 1667 MHz line overshoots that of the 1612 MHz line in about 80% of the targets. 52% and 26% of the 1612 and 1667 MHz sources, respectively, show linear polarization in at least some features. Circular polarization is more frequent, occurring in 78% and 32% of sources of the respective OH lines. The percentage polarization is usually small (<15%) reaching up to 50-80% in a few sources. Features of linearly polarized emission are usually weak (0.5-4Jy) and narrow (0.3-0.5kms^{-1}). The strength of magnetic field inferred from likely Zeeman pairs in two sources of a few mG is consistent with values reported elsewhere for those classes of objects. An upper limit of the electron density in the envelope of OH17.7-2.0 derived from the difference in the position angle of polarization vectors for the two OH lines is about 1cm^{-3}. Distinct profiles of polarization position angle at 1612 and 1667 MHz are seen in about one third of the sources and strongly suggest that the envelopes are permeated with structured magnetic fields. The geometry of the magnetic field is implicated as an important cause of the depolarization found in some PPN candidates. For the subset of targets which show axisymmetric shells in the optical or radio images we found a dominance of magnetic field components which are orthogonal to the long axis of the nebulae. This finding supports the hypothesis that such bipolar lobes are shaped by the magnetic field.Comment: Accepted for publication in A&A; 11 pages, 7 figure

Plutonium transfer to wildlife at legacy sites

When internalized within an organism’s body, plutonium (Pu) can be important in dose calculation due to its relatively high-energy alpha emissions (~5-6 MeV). In this paper we quantify transfer of Pu to a range of wildlife types at legacy nuclear weapons sites and evaluate the importance of body tissue Pu distribution in the transfer of Pu through the food chain. The paper presents new data from Maralinga, Australia, as well as past data from terrestrial and marine settings of the US nuclear research program

'Food hates' over the life course : an analysis of food narratives from the UK Mass Observation Archive

This article presents data from the UK Mass Observation Archive drawn from the 1982 Winter Food Directive, which focuses on memories of childhood food ‘hates’. Through our analysis of these data, we identify three main findings: (a) there is a discrepancy between individual-level and collective aggregate level food hates, which problematises the notion of commensality; (b) a small but powerful ‘outlier’ group of respondents, which we refer to as ‘visceral repulsors’, show relatively extreme reactions to certain foods throughout their lives; and (c) the duration and temporalities of food hates can be used to sketch a rough model of change and continuity of food hates over the life course. Finally, the discussion focuses on the food hate trajectories through the life course, situated in a social context, to explore the implications the findings may have for food and health policy more generally