Browsing by Author "Clark, GH"
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- ItemAssessment of the meteorological data and atmospheric dispersion estimates in the Ranger 1 uranium mining environmental impact statement(Australian Atomic Energy Commission, 1977-03) Clark, GHWind records from Jabiru, Northern Territory, Australia have been re-analysed to give atmospheric dispersion estimates of sulphur dioxide and radioactive contaminants associated with a proposed uranium mining and milling operation. Revisions in the plume rise equations have led to lower annual average sulphur dioxide air concentrations than those presented in the Ranger 1 Uranium Mining Environmental Impact Statement (RUMEIS). Likewise, the short term peak air concentrations of sulphur dioxide were all within the United States Environment Protection Agency (USEPA) air quality standards. Even though the radon gas inventory was revised upwards, predicted concentrations were only slightly higher than those in the RUMEIS. An attempt was made at a first estimate of the uranium dust source term caused by wind suspension from stockpiled ore and waste rock. In a preliminary analysis using a 'surface depletion' model, it was estimated that uranium dust air concentrations would be decreased by about an order of magnitude when dry deposition was
- ItemAtmospheric tracer tests and assessment of a potential accident at the National Medical Cyclotron Camperdown, NSW, Australia(Australian Nuclear Science and Technology Organisation, 1994-08) Clark, GH; Bartsch, FJK; Muller, HH; Stone, DJMIn order to assess the impact of a potential atmospheric release of radionuclides from the National Medical Cyclotron facility in Camperdown an atmospheric tracer release sampling and analysis system using SF6 was developed. During eight experiments conducted in a variety of meteorological conditions ten samplers were located in the vicinity of the Cyclotron building and other nearby buildings on the rapid downward movement of the tracer gas plume. The atmospheric dilution factors which lead to the highest observed air concentrations were then applied to the releases of I123and Xe123 from a potential accident scenario in order to assess the impact on nearby receptors. Even given the conservative assumptions about the release of I123 the estimated radiation doses were at least an order of magnitude below the international standards for doses to member of the public.
- ItemData volume of atmospheric tracer studies at Lucas Heights, NSW, Australia -1996 to 1997(Australian Nuclear Science and Technology Organisation, 2000-01) Clark, GH; Stone, DJM; Pascoe, JHA perfluorocarbon atmospheric tracer system has been used to investigate atmospheric dispersion processes in the region surrounding the Lucas Heights Science and Technology Centre. Tracers have been released from two locations: a laboratory vent near the ridge of the Woronora river valley and from the HIFAR research reactor ventilation system. Most studies have been conducted during the early to late morning periods when valley influences might be expected on dispersion of the tracer plume. This report summarises the meteorological and tracer air concentration data and makes comparisons with estimates from a simple gaussian dispersion model. It is intended that the data will also be used for evaluation of more elaborate wind field and atmospheric models.
- ItemDetailed meteorological interpretation of acoustic sounder records.(Australian Atomic Energy Commission, 1981-02) Clark, GH; Bendun, EOKTo quantify further the facsimile records from a monostatic acoustic sounder, a series of balloon and near surface meteorological measurements were made in the lower atmosphere under maritime conditions. Tests were concentrated on echo patterns associated with the developing atmospheric mixing layer and arrival of the sea breeze. Similar comparisons where made with an acoustic sounder operating at an inland location with continental climatic conditions. Extrapolation techniques were used to estimate the mixing layer depth between sunrise and initial emergence of the rising echo on the facsimile record. There was reasonable agreement in absolute height and rate of rise of the layer from comparison of the balloon and acoustic sounder measurements. The simple Carson model [D.J. Carson  Q.J.R. Meterol. Soc., 99:450-467] was also tested to allow extrapolation beyond disappearance of the rising echo. Under sea breeze conditions, the low altitude, elevated echo was associated with a stable temperature profile, a decrease in wind speeds and, frequently, a vertical shear in wind direction to the overlying background flow.
- ItemGeneral aspects of meteorology and wind flow patterns at the National Medical Cyclotron site Camperdown, NSW, Australia.(Australian Nuclear Science and Technology Organisation, 1994-06) Clark, GH; Bartsch, FJKAs part of an assessment into the consequences of a potential accident at the National Medical Cyclotron Camperdown NSW. Australia two meteorological stations were installed to monitor the winds temperatures and atmospheric dispersion conditions. The data will be used to assess environmental impacts of the Cyclotron's operation. In spite of the relatively poor performance of the stations the wind data indicated significant effects of local buildings and the general urban surface roughness features. The prevailing winds during the study were from the north-north-west at night and south-south-west or north-east sea breezes during the day. Atmospheric stability/dispersion categories were typical of an urban heat island location.
- ItemMeteorological and radiation measurements at Nabarlek, Northern Territory, June to July 1979(Australian Atomic Energy Commission, 1981-09) Clark, GH; Davy, DR; Bendun, EOK; O'Brien, BGA meteorological and radiation measurement program was conducted near the then developing uranium mine at Nabarlek in the Northern Territory. The two-filter tube radiation measuring technique was checked and compared with the continuous radon monitor and instant working level meter techniques. In general the Nabarlek meteorology was characterised by weak stable layers and good ventilation conditions with winds rarely less than 1ms -1. A comparison of wind measurements made near the open pit with those taken some 800 m away gave evidence of horizontal changes in the wind field over the site. Strong daytime winds gusting higher than 10 ms -1 caused a visible suspension of dust from the site. Dust deposition samples indicated that thorium-230 in air on site was a factor of twelve below the maximum permissible concentration for employees in Australia but uranium was lower by several orders of magnitude. The concentrations of radioactivity in the aquatic food pathway external radiation levels and radon daughter concentrations from deposited dust were likewise at least two orders of magnitude below the maximum concentrations permissible in Australia.
- ItemMeteorological research studies at Jervis Bay, Australia.(Australian Atomic Energy Commission, 1974-07) Clark, GH; Bendun, EOKA climatological study of the winds and temperatures from the Jervis Bay region which commenced in October 1970 has shown the presence of a coastal sea breeze and secondary bay breeze circulation system. In an attempt to define the influence of the Murray's Beach site on the local atmospheric dispersion, special smoke plume photography studies were conducted in the lower atmosphere. In June 1972 a meteorological acoustic sounding research programme was initiated at the Jervis Bay settlement. The aims of the research are to calibrate the sounder in terms of surface wind, turbulence and temperature measurements pertinent to a description of the lower atmospheric dispersion potential. Preliminary results on six months' data have shown encouraging correlations between the acoustic sounder patterns and particularly the wind direction turbulence traces.
- ItemMethods for conduct of atmospheric tracer studies at ANSTO.(Australian Nuclear Science and Technology Organisation, 2000-01) Clark, GH; Stone, DJM; Pascoe, JHA perfluorocarbon atmospheric tracer system has been developed to investigate atmospheric dispersion processes in the region surrounding the Lucas Heights Science and Technology Centre. This report discusses the tracer release sampling and analysis methods.
- ItemNuclear tools for characterising radiological dispersion in complex terrain: evaluation of regulatory and emergency response models(Inderscience Enterprises Ltd., 2005-07-01) Williams, AG; Clark, GH; Dyer, LL; Barton, RRoutine operations of a nuclear research reactor and its facilities offer opportunities for collection of rare environmental tracer datasets which can be used for atmospheric dispersion model evaluation studies. The HIFAR reactor near Sydney, Australia, routinely emits the radioactive noble gas Ar-41, and other radionuclides such as Xe-133 and Xe-135 are also emitted from nearby radiopharmaceutical production facilities. Despite extremely low emission levels of these gases, they are nevertheless detectable using state-of-the-art technology, and sensitive detectors have been placed at four locations in the surrounding region which features complex terrain. The high research potential of this unique dataset is illustrated in the current study, in which predictions from two atmospheric dispersion models used for emergency response are compared with Ar-41 peak observations from the detector network under a range of stability conditions, and long-term integrated data is also compared with a routine impact assessment model. © 2005, Inderscience Enterprises Ltd.
- ItemRevised radioactive airborne effluent discharge limit for the Lucas Heights Research Laboratories(Australian Nuclear Science and Technology Organisation, 1989-09) Petersen, MCE; Clark, GH; Bailey, GM; May, FGThe Australian Nuclear Science and Technology Organisation, formerly the Australian Atomic Energy Commission, is authorised under the NSW Radioactive Substances Act to release limited quantities of radioactive airborne effluent into the atmosphere from its facilities at the Lucas Heights Research Laboratories (LHRL). This authorisation is about twenty years old. This report proposes a revised site-wide airborne effluent discharge limit for the LHRL. The revised discharge limit is based upon the panoply of current International Commission on Radiological Protection (ICRP) and National Health Medical Research Council (NH & MRC) recommendations. It takes account of the operational changes at the LHRL and developments in radiation dosimetry and meteorology. The development and technical basis of the revised discharge limit, together with its relation to the ICRP recommendations, is briefly given. The formal discharge limit is to be approved by the NSW Radiological Advisory Council. The discharge limit consists of three components. First, a definition of the discharge limit expressed in terms of a fraction of the recommended ICRP dose limits. This limit is supported by, second, a compliance procedure and, third, a reporting procedure. In addition to the revised discharge limit, a number of operational and safety measures have to be further developed under the direction of ANSTO Management. The development of 'reference' levels' recommended by the ICRP is briefly described. In the present context, two reference levels for the quantities of activity released from each source will be established. The levels operate effectively like quality control measures in industry. They require certain operator actions if they are exceeded. The doses to individuals which are estimated for releases at the reference levels of releases of activity are well within the revised dose limits. From an operational point of view, these levels will vary with changing operations.
- ItemSome atmospheric dispersion, wind and temperature statistics from Jervis Bay, Australian Capital Territory, 1972 to 1974(Australian Atomic Energy Commission, 1985-07) Clark, GHA meteorological study of winds temperatures and Pasquill stability categories was conducted in the coastal conditions at Jervis Bay. Three Pasquill stability categorisation schemes were compared. These indicated a predominance of neutral to slightly unstable conditions. During the daytime north bay breezes and north-east sea breezes were most common together with on-shore south-east winds. Off-shore south-west winds prevailed during winter and were observed most frequently at night.
- ItemSome meteorological parameters for atmospheric dispersion modelling at Lucas Heights, NSW, Australia, 1975 to 1983(Australian Atomic Energy Commission, 1985-10) Clark, GHMeteorological data collected in the years 1975 to 1983 at the AAEC's Research Establishment at Lucas Heights New South Wales Australia have been summarised. Wind speed direction and turbulence trace types from 7 and 49 m temperature difference between 9 and 49 m ambient temperature and precipitation rates have been extracted as 30 minute averages. Seasonal wind speed and direction roses are summarised for 7 and 49 m together with wind direction persistence statistics which are relevant to short-term (accident) releases of atmospheric pollutants. A 'split-sigma' approach has been adopted for definition of the atmospheric stability categories: a 'turbulence' method using the wind direction turbulence trace types for the horizontal diffusion category; and the US Nuclear Regulatory Commission temperature gradient criteria are combined with Smith's 1972 scheme for the vertical diffusion estimates. Statistics on 10, 50 and 90 per cent probability and average wind speeds and atmospheric stabilities are also analysed. An extensive data summary is included.
- ItemStack monitoring at ANSTO and comparison with international guidelines(Australian Nuclear Science and Technology Organisation, 2002-09) Mukherjee, B; May, FG; Clark, GHThis report reviews the sampling systems at ANSTO in terms of current international guidelines for the design and operation of stack monitoring at nuclear facilities. A review of the literature and enquiries overseas have revealed the principal international guidelines for stack sampling and on-line monitoring are: 1. Monitoring of Radioactive Releases to Atmospheres from Nuclear Facilities, Technical Guidance Note M11, UK Environmental Agency 1999. This Technical Guidance Note provides guidance on the monitoring of airborne releases from nuclear facilities regulated under the UK Radioactive Substances Act (RSA 1993). For sites in England and Wales, the authorisations are issued by the Environmental Agency and in Scotland by the Scottish Environmental Protection Agency. 2. Sampling and Monitoring Releases of Airborne Radioactive Substances from Stacks and Ducts of Nuclear Facilities. American National Standard ANS/HPSN13.1.1999.
- ItemAn updated analysis of the Lucas Heights climatology - 1975 to 1996(Australian Nuclear Science and Technology Organisation, 1997-06) Clark, GHMeteorological data collected from 1975 to 1996 in the Lucas Heights region have been summarised to provide an update on the climatology. Initially data were recorded in analogue form but since 1991 advanced digital recording systems have allowed more accurate and extensive statistics to be analysed. Since 1993 a network of meteorological stations has been installed through the surrounding area to investigate the influence of complex terrain on wind flow and atmospheric dispersion patterns. A large data volume is presented together with some initial interpretation of these complex terrain influences on the Lucas Heights region climatology.
- ItemUpdated analysis of the Lucas Heights climatology - 1991 to 2003(Australian Nuclear Science and Technology Organisation, 2003-12) Clark, GHMeteorological data collected from 1991 to 2003 in the Lucas Heights region have been summarised to provide an update on the climatology. This report represents analysis of data collected at the Lucas Heights Science and Technology Centre since 1991 when an advanced digital recording system was installed. The small network of meteorological stations installed in the surrounding region since 1993 has allowed an investigation of the influence of complex terrain on wind flow and atmospheric dispersion patterns. For a period between 1999 and 2001 a Bureau of Meteorology disdrometer was installed at Lucas Heights to investigate raindrop size distributions. A large number of statistical summaries for all meteorological data are presented in in two appendices at the end of the report as a resource for reference purposes.