Browsing by Author "Levins, DM"

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    AMS measurement of 129I, 36C1 and 14C in underground waters from Mururoa and Fangataufa atolls
    (Elsevier, 2000-10) Jacobsen, GE; Hotchkis, MAC; Fink, D; Child, DP; Tuniz, C; Sacchi, E; Levins, DM; Povinec, PP; Mulsow, S
    AMS analyses of 36Cl, 129I and 14C in underground water have been performed as part of IAEA’s assessment of the radiological situation at Mururoa and Fangataufa atolls. The samples consisted of waters from monitoring wells, and from two cavity-chimneys created by underground nuclear tests. The water samples from the monitoring wells contained varying concentrations of radionuclides, with the highest concentrations of radionuclides found in the two test cavity-chimneys. A comparison of the concentrations of radionuclides determined by AMS, 36Cl and 129I, and with radionuclides determined using conventional methods, 3H, 90Sr and 137Cs, shows a reasonable correlation. However, some differences in behaviour, mainly attributed to differences in the sorption characteristics of the elements, are discernible. The concentrations of radionuclides in the underground environment were used to validate geosphere transport models. © 2000 Elsevier Science B.V.
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    ANSTO's radioactive waste management policy: preliminary environmental review
    (Australian Nuclear Science and Technology Organisation, 1996-05) Levins, DM; Airey, PL; Breadner, B; Bull, PS; Camilleri, A; Dimitrovski, L; Gorman, T; Harries, JR; Innes, RW; Jarquin, E; Jay, G; Ridal, A; Smith, AM
    For over forty years radioactive wastes have been generated by ANSTO (and its predecessor the AAEC) from the operation of nuclear facilities the production of radioisotopes for medical and industrial use and from various research activities. The quantities and activities of radioactive waste currently at Lucas Heights are very small compared to many other nuclear facilities overseas especially those in countries with nuclear power program. Nevertheless in the absence of a repository for nuclear wastes in Australia and guidelines for waste conditioning the waste inventory has been growing steadily. This report reviews the status of radioactive waste management at ANSTO including spent fuel management treatment of effluents and environmental monitoring. It gives details of: relevant legislative regulatory and related requirements; sources and types of radioactive waste generated at ANSTO; waste quantities and activities (both cumulative and annual arisings); existing practices and procedures for waste management and environmental monitoring; recommended broad strategies for dealing with radioactive waste management issues. Detailed proposals on how the recommendations should be implemented is the subject of a companion internal document the Radioactive Waste Management Action Plan 1996-2000 which provides details of the tasks to be undertaken milestones and resource requirements.
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    The development and testing of Synroc C as a high level nuclear waste form
    (Cambridge University Press, 2011-02-15) Reeve, KD; Levins, DM; Ramm, EJ; Woolfrey, JL; Buykx, WJ
    The current status of SYNROC C research and development by the Australian Atomic Energy Commission is reviewed. A non-radioactive fabrication demonstration line designed to produce 10 cm o.d., 90 cm long, cylinders of SYNROC canned in stainless steel by the method of in-can hot pressing is being commissioned. Leach tests are proving the excellent leach resistance of SYNROC. Accelerated radiation damage testing using fast neutrons has simulated storage times of up to 6.7×105 years. Thermophysical properties of SYNROC have been measured over the temperature range 20–650°C. © Materials Research Society 1982
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    The development and testing of SYNROC for high level radioactive waste fixation
    (Australian Atomic Energy Commission, 1981-02-23) Reeve, KD; Levins, DM; Ramm, RJ; Woolfrey, JL; Buykx, WJ; Ryan, RK; Champan, JF
    Research and development on the SYNROC concept for high level radioactive waste fixation commenced at the Australian Atomic Energy Commission Research Establishment, Lucas Heights, in March 1979, in collaboration with a complementary program at The Australian National University (ANU). The present paper reports progress in the project's second year and reviews its current status. An inactive 30 kg-scale SYNROC fabrication line incorporating in-can hot pressing as the fabrication step has been built for operation in mid-1981. Atmospheric pressure and hydrothermal leach tests are demonstrating the excellent leach resistance of SYNROC. Accelerated radiation damage tests using fast neutrons are simulating damage in SYNROC for periods of close to 10/sup 6/ years. In supporting research, mineral phase development, impact friability and thermophysical properties of SYNROC are being studied.
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    From Rum Jungle to Wismut - Reducing the environmental impact of uranium mining and milling
    (The Institution of Engineers Australia, 1994-05-01) Zuk, WM; Jeffree, RA; Levins, DM; Lowson, RT; Ritchie, AIM
    Australia has a long history of uranium mining. In the early days, little attention was given to environmental matters and considerable pollution occurred. ANSTO has been involved in rehabilitation of a number of the early uranium mining sites, from Rum Jungle in Australia's Northern Territory to Wismut in Germany, and is working with current producers to minimise the environmental impact of their operations. ANSTO's expertise in amelioration of acid mine drainage, radon measurements and control, treatment of mill wastes, management of tailings, monitoring of seepage plumes, mathematical modelling of pollutant transport and biological impacts in a tropical environment are summarized.
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    Heavy water production - a review of processes
    (Australian Atomic Energy Commission, 1970-09) Levins, DM
    Methods of heavy water production are examined in detail. Processes based on chemical exchange have the greatest potential for further development but distillation, electrolytic and chromatographic methods are also discussed. In the immediate future most of the world output of heavy water will be produced by hydrogen sulphide/water exchange (the GS process) but there is limited scope for further reduction in GS production costs. Recent advances in process development make the ammonia/hydrogen route an attractive alternative since the enrichment obtainable in each stage is greater while the energy consumption is less. A variation of the ammonia/hydrogen scheme involving the use of amines as additives to, or substitutes for ammonia also appears promising. The greatest obstacle to the development of either the ammonia/hydrogen or amine/hydrogen schemes on a large scale is the limitation on the supply of hydrogen. Ammonia synthesis gas is currently the most plentiful supply available but 1500 tonnes/day of ammonia capacity is needed for each 100 tonnes of heavy water produced annually. Unlimited production could be achieved using an equilibration stage in which hydrogen depleted in deuterium is exchanged with water at high temperature. The economics of this scheme depend on the development of a satisfactory catalyst for water/hydrogen equilibration. Distillation of water, methane and hydrogen have been proposed as economic routes to heavy water production but design studies and experimental data would need to be clarified if optimistic forecasts are to be substantiated. Processes based on chromatography or selective adsorption have received scant attention in the past. Many problems would need to be overcome before such processes could be adapted to large scale production of heavy water, but in view of recent advances in plant scale chromatography, they should be re-examined.
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    Leaching of heavy metals and radionuclides from uranium tailings
    (Institution of Chemical Engineers : Institution of Engineers, Australia : Royal Australian Chemical Institute, 1985-08-25) Ring, RJ; Levins, DM; Cooper, MB
    This paper presents results of accelerated column leaching tests carried out to estimate the long-term release rate of heavy metals and radionuclides from Australian uranium tailings. The effect of limestone and lime treatment before impoundment is examined. A simple model is proposed which can be used, in association with seepage data, to estimate the total quantities of contaminants released over many centuries.
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    Management of wastes from the processing of rare earth minerals
    (Institution of Engineers Australia, 1988-08-28) Hart, KP; Levins, DM
    Australia is the leading producer and exporter of the rare earth mineral, monazite, but currently does not process it beyond the physical beneficiation stage. Recent discoveries of new uses for rare earth has renewed interest in monazite processing in Australia. Two proposals of rare earth processing plants have been announced and a number of other companies are engaged in feasibility studies. Chemical processing of monazite involves digestion in caustic soda to 'crack' the phosphate matrix, dissolution of the rare earths in acid and their separation by multi-stage solvent extraction usually in mixer-settlers. The processing is complicated by the presence of 4-8 wt% thorium and 0.1-0.3 wt% uranium in the monazite. Experiments have shown that lead-210 and uranium are partially solubilized in the caustic digestion stage and radium is dissolved along with the rare earths. Over 99.5% of the radium can be precipitated as barium/radium sulphate by the addition of barium chloride and soluble sulphate. This radium-bearing solid waste can be combined with the uranium/thorium residue so that essentially all the radionuclides are contained in the one waste stream. The volume of this waste stream is not large and it is feasible to store it on-site in an engineered facility. The safe disposal of this waste would be facilitated by the establishment of a national facility for radioactive and other toxic wastes.
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    Performance of a thermosiphon evaporator for concentration of uranyl nitrate solutions
    (Australian Atomic Energy Commission, 1973-05) Levins, DM; Alfredson, PG
    The performance of a thermosiphon evaporator, with a heat transfer area of 0.74 m2, for the concentration of uranyl nitrate solutions up to 1000 gU ℓ-1 is evaluated. The effects of steam pressure, uranium concentration and liquid submergence on the overall heat transfer coefficient are reported and a method of designing thermosiphon evaporators handling concentrated uranyl nitrate solutions is proposed. Pressure drop characteristics of two packings used in the steam stripping and de-entrainment sections of the evaporator are also given. Overall heat transfer coefficients in the range 1.4 - 2.5 kW m-1 K-1 were obtained at uranyl nitrate concentrations up to 1000 gU ℓ-l. Heat transfer to uranyl nitrate solutions below a concentration of 100 gU ℓ-1 was satisfactorily predicted by employing conventional heat transfer correlations using physical property data for water. Results for more concentrated solutions were successfully correlated using an empirical correction factor which accounts for the change in physical properties of the boiling solution with concentration.
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    Radioactive waste management
    (Australian Atomic Energy Commission, 1975-08) Alfredson, PG; Levins, DM
    Present and future methods of managing radioactive wastes in the nuclear industry are reviewed. In the stages from uranium mining to fuel fabrication, the main purpose of waste management is to limit and control dispersal into the environment of uranium and its decay products, particularly radium and radon. Nuclear reactors produce large amounts of radioactivity but release rates from commercial power reactors have been low and well within legal limits. The principal waste from reprocessing is a high activity liquid containing essentially all the fission products along with the transuranium elements. Most high activity wastes are currently stored as liquids in tanks but there is agreement that future wastes must be converted into solids. Processes to solidify wastes have been demonstrated in pilot plant facilities in the United States and Europe. After solidification, wastes may be stored for some time in man-made structures at or near the Earth's surface. The best method for ultimate disposal appears to be placing solid wastes in a suitable geological formation on land.
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    Radioactive waste management at ANSTO - managing current and historic wastes
    (International Atomic Energy Agency (IAEA), 2001-11-05) Harries, JR; Dimitrovski, L; Hart, KP; Levins, DM
    The Australian Nuclear Science and Technology Organisation (ANSTO) site at Lucas Heights has operated as a nuclear site for over 40 years and most of the waste generated is still stored at the site. The 10 MW heavy water research reactor (HIFAR) has operated at Lucas Heights for over 40 years with associated radioisotope and radiopharmaceutical production facilities. HIFAR is scheduled to shut down in 2005 and a contract has been signed for a multipurpose 20 MW research reactor which, amongst other uses, will provide continued radiopharmaceutical production and neutron beam research. In addition to these activities, a wide range of nuclear science and technology R and D is carried out at the site. In 1995, ANSTO issued its radioactive waste management policy which made a commitment to: (a) complying with all regulatory requirements; (b) ensuring that radiation dose rates were kept as low as reasonably achievable (the ALARA principle); (c) disposing of waste when appropriate disposal routes are available; and (d) being in accord with international best practice. An extensive audit was earned out of ANSTO's waste management facilities and practices. The recommendations arising from this audit became the basis for an integrated five year Waste Management Action Plan, which began in 1996. The Plan dealt with legacy issues that had arisen from the accumulation of the radioactive waste at Lucas Heights. It involved construction and operation of improved storage facilities for low- level radioactive waste, better monitoring of existing storage facilities for spent research reactor fuel and intermediate level liquid wastes, and conversion of liquid and solid wastes into more stable forms suitable for prolonged storage. Solidification of the intermediate level liquid waste has been a major priority of the Waste Management Action Plan. This acidic waste is generated during the production of molybdenum-99 for radiopharmaceutical use. A hot cell process was developed involving concentration of the waste by evaporation, destruction of the ammonium ion by a novel process and solidification of the waste as a uranium-rich salt. Routine processing of the liquid waste commenced in 1999 and to date over 2 m3 of liquid waste has been converted to a solid. The solidified waste is stored in high- integrity stainless steel vessels with a design life of at least 50 years. Another project under way will convert this solid waste into a more durable waste form suitable for long term storage or disposal. Two waste forms were initially considered; a titanate-based variant of synroc and cement. Laboratory scale testing established the feasibility of producing the titanate based ceramic with a high waste loading (∼44 wt % U) and the superior performance of this matrix over cement. Engineering scale development of a hot cell process for production of the ceramic waste form is under way. Much of the historic waste was characterised when it was generated by external dose with little information recorded about the radionuclide content. In 1996, a radioactive waste scanning system was installed to determine the radionuclide content of drums of historic waste. A data base system is being developed to integrate the characterisation, treatment and location information on the radioactive waste at ANSTO including the results from the drum scanning measurements. An important objective of ANSTO's waste management policy is minimization of radioactive waste generated and stored. This is being achieved by a number of strategies: for example, in one radioisotope production area a threefold reduction in waste volume has been achieved by separating non-radioactive waste from radioactive waste at the source. A substantial reduction in radioactive gas emissions during the production of molybdenum-99 has also been achieved by changes in waste processing operations and procedures. As well as focussing on historical waste issues a number of initiatives within ANSTO aimed at improving current processes and waste systems are being carried out. Currently, waste water from active drains at ANSTO is treated by a flocculation/centrifugation process and discharged to the sewer. Over the next few years, ANSTO plans to upgrade its effluent treatment facilities using state-of-the-art technology. Pilot plant demonstration of a membrane-based process is in progress after which a specification will be prepared for a full scale plant. Planning is also under way for a new facility to treat and package ANSTO's radioactive waste in readiness for disposal in the national repository for low level and short lived intermediate level waste. © Author(s) 2001
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    Reduction of capital costs in reprocessing power reactor fuels: a design study
    (Australian Atomic Energy Commission, 1973-09) Costello, JM; Levins, DM
    The design and cost structures of conventional types of commercial reprocessing plant have been reviewed. Process functions offering the greater potential saving in capital cost have been identified. Unorthodox approaches to philosophies of plant layout, maintenance procedures, and radiation shielding have been formulated with the primary aim of reducing capital cost. Four conceptual designs have been made of a large scale reprocessing plant based on existing shear leach-solvent extraction technology, incorporating novel equipment types and unorthodox design philosophy. Preliminary capital cost estimates for the designs are in the range $37-41 x 10 6, indicating a 30-37% reduction in comparison with a conventional plant of identical capacity and scope. Additional costs exceeding $30 x 10 6 could be incurred for refinement to effluent treatment and storage systems envisaged for environmental protection for any type of reprocessing plant.
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    Regeneration of caustic potash solution used for the disposal of gaseous fluorides
    (Institution of Chemical Engineers, 1975-08-23) Royston, D; Burwell, A; Janov, J; Le Page, AH; Levins, DM; Ring, RJ; Vilkaitis, VK
    A system for the disposal of fluorine and gaseous hydrogen fluoride was developed as part of an experimental 1500 A fluorine cell facility used to investigate the production of fluorine. The design, operation and performance of the plant have been described in detail by Royston et al.1,2. The cell produced fluorine and hydrogen at 0.24 & s-1 with both gases containing approximately l0 vol.% hydrogen fluoride. These off—gases were disposed of continuously by scrubbing with 5-8.5 wt.% caustic potash solution which was regenerated by reaction with lime on a batch basis. This paper outlines the selection of the system and describes its operation and performance.
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    Spray drying of ammonium diuranate slurries
    (Australian Atomic Energy Commission, 1972-10) Levins, DM; Alfredson, PG; Hirst, RC; MacBride, PR
    Slow and fast settling ammonium diuranate (ADU) slurries were dried in a one metre diameter laboratory spray drier using either pneumatic or centrifugal atomisation. Uniform, fine, dry powders were obtained with both atomisation techniques but pneumatic atomisation was preferred. Spray drying did not adversely affect the properties of the subsequent UO2 powder and pellets. It was not necessary to treat the ADU feed slurry to remove ammonium nitrate in solution. A theoretical model of droplet evaporation during spray drying is developed, taking into account droplet size distribution, gas-spray hydrodynamics and heat transfer rates. This model satisfactorily accounts for the observed operational characteristics of the drier.