Browsing by Author "Harries, JR"

Now showing 1 - 13 of 13
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    Acid drainage from waste rock dumps and mine sites (Australian and Scandinavia)
    (Australian Nuclear Science and Technology Organisation, 1990-05) Harries, JR
    This report reviews the literature from Australia and Scandinavia on acid drainage from pyritic waste rock dumps with an emphasis on measurements and theory of processes that control the rage of oxidation and the release of pollutants. Conditions within waste rock dumps have been measured at several mine sites and a range of rehabilitation treatments have been tried to reduce the release of pollutants. A number of models have been proposed to calculate air flow water transport and geochemistry. The data and experience at the mine sites are compared with predictions of the models.
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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 circulation of deep water in the Tasman and Coral Seas
    (Australian Atomic Energy Commission, 1976-07) Harries, JR
    The physical oceanography of the Tasman and Coral Seas is reviewed with an emphasis on the deep currents. There are many uncertainties in the deep circulation pattern. The available data are used to develop an idealised circulation to estimate the likely path taken by water flowing from a depth of 5000 m in the Tasman Sea. The model suggests that the water would finally reach the surface layers south of the Antarctic Convergence with a median delay of 600 years.
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    Correlation and flux tilt measurements of coupled-core reactor assemblies
    (Australian Atomic Energy Commission, 1976-01) Harries, JR
    The systematics of coupling reactivity and time delay between cores have been investigated with a series of coupled-core assemblies on the AAEC Split-table Critical Facility. The assemblies were similar to the Universities' Training Reactor (UTR), but had graphite coupling region thickness of 450 mm, 600 mm and 800 mm. The coupling reactivity measured by both the cross-correlation of reactor noise and the flux tilt methods was stronger than for the UTRs, but showed a similar trend with core spacing. The cross-correlograms were analysed using the two-node model to derive the time delays between the cores. The time delays were compared with thermal neutron wave propagation, and found to be consistent when the time delays were added to the individual node response-function delays.
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    Deep circulation in the Indian and Pacific Oceans and its implication for the dumping of low-level radioactive waste
    (Australian Atomic Energy Commission, 1980-06) Harries, JR
    The complexity of ocean transport processes has meant that the limits for the dumping of low-activity radioactive wastes have had to be based on very simplified models of the oceans. This report discusses the models used to determine dumping limits and contrasts them with the known ocean circulation patterns. The deep circulations of the Indian and Pacific Oceans are reviewed to provide a basis for estimating the possible destinations and likely transit times for dissolved material released at the ocean floor.
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    Heat source probe for measuring thermal conductivity in waste rock dumps.
    (Australian Atomic Energy Commission, 1985-10) Blackford, MG; Harries, JR
    The development and use of a heat source probe to measure the thermal conductivity of the material in a waste rock dump is described. The probe releases heat at a constant rate into the surrounding material and the resulting temperature rise is inversely related to the thermal conductivity. The probe was designed for use in holes in the dump which are lined with 50 mm i.d. polyethylene liners. The poor thermal contact between the probe and the liner and the unknown conductivity of the backfill material around the liner necessitated long heating and cooling times (>10 hours) to ensure that the thermal conductivity of the dump material was being measured. Temperature data acquired in the field were analysed by comparing them with temperatures calculated using a two-dimensional cylindrical model of the probe and surrounding material and the heat transfer code HEATRAN.
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    Inverse kinetics reactivity measurements on the materials testing reactor HIFAR.
    (Australian Atomic Energy Commission, 1978-12) Harries, JR
    Inverse kinetics method of reactivity determination is compared with the asymptotic doubling time method and found to give more accurate results for the materials testing reactor HIFAR. The differential reactivity worth profile of the HIFAR coarse control arms is measured using the inverse kinetics method and the reactivity worth is found to be proportional to M-º.75±0.10, where M is the mass of fissile material in the reactor. The fuel mass dependence is shown by perturbation theory to be a function of the relative flux depression at the fuel. The temperature coefficient of reactivity is found to be proportional to M-1.01±0.16.
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    Measurement of the dynamic response of the materials testing reactor HIFAR
    (Australian Atomic Energy Commission, 1978-01) Harries, JR; Wilson, DJ
    Power transients were initiated in the HIFAR Materials Testing Reactor by altering both the temperature of the primary coolant circuit and the flow rate of the primary coolant. Analysis of the time variation of the reactor power and the D2O temperature provided information about the flow of D2O in the reactor aluminium tank and the time response of the negative power coefficient. The experimental power transients were compared with calculations carried out with the HIDYN code, which combines the neutron kinetics with the primary coolant characteristics.
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    Migration of Cs-137 and Co-60 in the Australian arid zone
    (Cambridge University Press/Springer Nature, 2000) Payne, TE; Harries, JR; Itakura, T
    Batch adsorption experiments with Cs-137 and Co-60 were undertaken using representative samples of geologic materials from the arid region that has been selected for an Australian low-level waste repository. The results indicate that the pH is the main factor affecting the adsorption of Co-60 but has little influence on the sorption of Cs-137. The ionic strength affects Cs sorption, with a decrease in Kd associated with higher ionic strength. Selective sorption sites on mica and illite control uptake of trace Cs, whereas the high total site availability of smectite is significant when the total Cs is higher (1 mmol/L). The effects of mineralogy on Cs sorption which were observed for these complex materials confirmed previous results reported for pure minerals. © 2000 Materials Research Society
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    The possible transmutation of radioactive waste from nuclear reactors
    (Australian Institute of Physics, 1974-05-21) Harries, JR
    A nuclear reactor power program produces high level long lived radio-active wastes. The high level activity is associated with fusion products, but beyond 400 years the principal waste hazard is from transuranic elements produced in the reactor. Several schemes have been proposed for the transmutation of the problem isotopes into more easily handled isotopes. The neutron flux in a thermal reactor is not high enough to significantly reduce the longer lived fission product isotopes 90Sr and 132Gs, but the transuranic elements can be reduced by recycling through power reactors. The limitation on recycling of the transuranic elements is the separation process to remove trace quantities from the wast stream. In fact reactors the transuranic elements are the principal fuel and fast reactor waste contains only half as much 90Sr as thermal reactors. However, the overall waste hazard is similar to thermal reactors. A sufficiently intense neutron flux for fission product transmutation could perhaps be produced by a spallation reactor driven by a proton linear accelerator or a controlled thermonuclear reactor. However, both concepts are still some years in the future. Transmutation by accelerator sources of protons, electron or gammas tend to require more energy than neutron transmutation.
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    The prompt neutron decay constant of the MOATA reactor and related coupled-core assemblies
    (Australian Atomic Energy Commission, 1976-03) Knott, RB; Harries, JR
    The correlation functions of the neutron noise have been used to determine the prompt neutron decay constant, α, for the AAEC reactor Moata - a Universities1 Training Reactor (UTR). The basic characteristics of the UTR system are two coupled 235u fuel cores, hydrogen moderated and graphite reflected. To investigate this type of reactor in greater detail, a series of 'mockup' assemblies was constructed on the AAEC Split-table Zero-power Critical Facility. A value of α was experimentally determined for each assembly, and the effects on α of core separation, fuel arrangements, perturbations to the coupling region, and detector positions were investigated. A comparison with previous results for the Moata reactor and with results for similar UTR systems was carried out. Using a two-dimensional neutron diffusion and kinetics computer code, the prompt neutron generation time, Λ, and the effective delayed neutron fraction, β, were calculated for each assembly. The results from the two-dimensional calculations were consistent with experiment, but the difficulty of modelling the neutron leakage limited the accuracy of the calculated α. Improved agreement with experiment was obtained using a three-dimensional diffusion calculation.
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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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    The transmutation of radioactive reactor waste
    (Australian Atomic Energy Commission, 1974-09) Harries, JR
    The feasibility of transmuting the hazardous long-lived radioactive isotopes present in reactor waste to stable or short-lived isotopes is examined. Even to transmute only the most hazardous fission product isotopes, caesium-137 and strontium-90, by protons, electrons or gamma rays requires more electrical energy than the reactor can produce. Neutron transmutation of these fission products would require high neutron fluxes such as might be obtainable from a controlled thermonuclear reactor or a spallation target. The development of both systems is many years in the future, and the spallation system would use almost all of the reactor power output. The neutron transmutation of the transuranic component of the waste is feasible by recycling in nuclear reactors. The transmutation occurs by neutron absorption and fission, so that the waste is converted to a smaller quantity of less hazardous fission product and the fission energy is utilised.