Browsing by Author "Petersen, MCE"

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    An apparatus for measuring the energy and angular distribution of electrons ejected in ion-atom collisions
    (Australian Atomic Energy Commission, 1978-07) Gibson, DK; Petersen, MCE
    There is a need for further data on the energy and angular distribution of electrons ejected from atoms and molecules by ion impact. An apparatus in which simultaneous measurements can be made of the energy and angular distributions of such electrons is described. The advantages of the apparatus are the possibility of fast data collection and the ability to make measurements over the whole range of scattering angle. Preliminary tests and a trial measurement with the apparatus are described.
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    The distribution of adsorbing and non-adsorbing solutes in wide rivers.
    (Australian Atomic Energy Commission, 1977-11) Petersen, MCE
    Solutions are given to the complete two-dimensional transport equations for the distribution of both adsorbing and non-adsorbing solutes released from a continuous point source into a wide river flowing with uniform velocity and with constant anisotropic turbulent diffusion coefficients. These results contain the asymptotic Gaussian expressions often used to describe the far field distributions. The present results allow the near field distributions to be evaluated in situations where complex source distributions occur which do not substantially alter the turbulent diffusion coefficients. Several simple formulae are presented for the non-adsorbing case; these give the length, breadth and area of a plume contour associated with a particular concentration reference level.
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    HIFAR safety analysis: frequency and offsite consequences of fault sequences initiated by within-plant failures
    (Australian Atomic Energy Commission, 1986-05) McCulloch, DB; Corran, ER; Petersen, MCE; Nicholson, FD; Innes, RW
    HIFAR fault sequences, initiated by failures of within-plant equipment and operational procedures, are analysed using probabilistic methods, and their frequencies estimated. Sequence consequences are estimated in terms of potential radiation doses to an individual at 1.6 km radius from the reactor, expressed in terms of emergency reference levels recommended by the National Health and Medical Research Council for consideration of limited evacuation. The results show that the public risk from all such sequences is extremely low.
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    Measurement of the energy and angular distribution of electrons
    (The Australian Insitute of Nuclear Science and Engineering, 1979-02-05) Gibson, DK; Petersen, MCE
    Knowledge of the energy and angular distributions of electrons ejected in collisions between fast particles (10-100 keV), particularly protons, is of great importance in understanding of the damaging effects of neutrons in biological matters. For this reason the AAEC has a program to extend the knowledge of these electron distributions to the atoms and molecules which constitute living cells. Clearly there are a large number of measurements involved in such a project, the ejection, angle, ejection energy, incident ion species and energy and the target atom all being variables. For this reason our aim was to design an apparatus which would permit rapid accumulation of data. Our design is based on the 30° electrostatic analyser, in which the charged particles originating from an object point travel in a filed free region from some distance before entering a plane electrostatic field at 30° to the field boundary. The particles are focused, to second order, along a line situated outside the field region, symmetrically placed with respect to the object point. The principle if the "fountain" spectrometer has been applied to this analyser, resulting in a device which accepts particles from a point source through a small annular gap into an electrostatic field region. In applying this analyser to measurements of ejected electrons, a proton beam is fired through one point of the input annular slit. The protons, with, with energies mostly are least 100 times that of the electrons they produce, are deflected only to a negligible extent and pass out of the analyser through a small hole in the back electrostatic plate. Electrons originating from collisions at the object point enter the analyser at all points around the annual input slit, each point corresponding to a different eject angle, varying between 0 and 120°. Cannelton detectors placed around the output focal circle simultaneously measure electrons at one energy and variety of angles. Varying the electrostatic field permits the energy to be scanned. A number of measurements have been made with this apparatus.
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    Revised 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, FG
    The 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.