[en] The Sterile Insect Technique (SIT) aims to suppress or eradicate pest populations by flooding wild populations with sterile males. To control fruit fly million of flies of both sexes are mass reared at the Gosford Post-Harvest laboratory near Sydney, mixed with sawdust and fluorescent dye at the pupal stage and transported to Ansto where they are exposed to low dose of 70-75Gy of gamma radiation from a Cobalt-60 source. Following irradiation the pupae are transported to the release site in plastic sleeves then transferred to large plastic garbage bins for hatching. These bins are held at 30 deg. C. to synchronise hatching and files are released 48-72 hours after hatching begins. In most cases these bins are placed among fruit trees in the form of an 800 metre grid. This maximises survival of the emerging flies which are released on an almost daily basis. Progress of the SIT program is monitored by collecting flies from traps dotted all over the infested site. The ratio of sterile to wild flies can be detected because the sterile files are coated with the fluorescent dust which can be seen under ultra-violet light. If the SIT program is successful entomologists will trap a high proportion of sterile flies to wild flies and this should result in a clear reduction in maggot infestations. Surveillance, quarantine, and trapping activities continue for 8 or 9 months to check for any surviving pockets of infestation. If any are found the SIT program is reactivated. These programs demonstrated that SIT was an efficient and environmental friendly non-chemical control method for eradicating outbreaks or suppressing fruit fly populations in important fruit growing areas. ills

[en] Short communication. ill

[en] Since the introduction of technetium-99m labelled radiopharmaceuticals used as imaging agents in the nuclear medicine departments of Australian hospitals, patients have voiced concern about the effect of having radioactive materials injected into their bodies. The danger of X-ray exposure is widely known and well accepted, as is exposure to ultrasound, computed tomography scans and other imaging techniques. However, radioactivity is an unknown, and fear of the unknown can occasionally lead to patients refusing to undergo a nuclear medicine procedure. The authors emphasised that the radiation dose to a patient from a typical procedure would depend on the patient's medical history and treatment; the average dose being approximately 50 times the exposure received from the natural environmental background radiation. Furthermore, over an extended period the body can repair most minor damage caused by radiation, just as the body can repair the damage caused by sunburn resulting from too much exposure to sunlight. The risk of genetic effects as a result of a medical radiation dose is than very small

[en] Sol-gel processing techniques have been used at Ansto to prepare a wide range of advanced ceramic materials, including Synroc, nanoceramics, electronic ceramics, bioceramics, thin films and membranes and multicomponent powders. The major current project involves the production of uniform, 30 to 50 microns spherical Synroc particles, with a high sorption capacity for nuclear waste. These particles are produced by spray-drying a concentrated titania/zirconia sol manufactured using proprietary techniques developed by the Advanced Materials Program at Ansto. A ceramic membrane filter is also being developed for the industrial processing of hot liquids. The filtration membrane is fabricated using sol-gel methods to produce a ceramic layer about 10 microns thick with closely controlled nano-sized pores. ills

[en] The design philosophy of the Australian Medical Cyclotron safety features is presented. The main features include shielding against prompt neutron and gamma radiation, operational safety and safe handling of radioisotopes and waste. The results of the safety monitoring to date show that the cyclotron operation causes no significant increase of radiation dose level. ills

[en] Ansto's high resolution neutron powder diffractometer was recently relocated after ten years of service as part of an overall expansion of Ansto's neutron scattering facilities. This instrument, the most heavily used neutron scattering instrument, is now being recommissioned. ICI Advanced Ceramics has found neutron diffraction an invaluable technique for determining the phase composition of partially stabilised zirconia. Accurate control of phase composition is critical for achieving the high performance properties of this important engineering ceramic material. Other applications of the neutron scattering briefly presented include the crystallography of caustic soda, the mapping of strain and inferred stresses in objects ranging from special steels plates to turbine blades. A simple but interesting recent application has been the determination of stress in diamond. ills

[en] Ansto's Environmental Chemistry Program was contracted to undertake a study to identify particulate metals in the sea surface micro layer and underlying water column. This project has the specific aims of compiling an inventory of case study concentrations of particulate trace metals occurring in micro layers, slicks and subsurface wasters at the present and future Malabar outfall sites and comparing these with ambient concentrations. The fate of different particulate components and trace elements in the sewage is dependent on particle size, density and continuing transformations associated with the sediments, water column or the sea surface. Phase one of the Malabar outfalls project involved sampling two inshore sites and two offshore sites. Technetium-99m tracer, which has a six hour half-life, pumped into the effluent stream has been used to determine the height of the rise of the plume, the thickness and with of the affected zone and the initial and subsequent dilution and dispersion. At the end of the field trials the data collected was combined to produce a four dimensional picture of the effluent dispersion which was compared to the behaviour predicted by the computer models. The general conclusion to date is that the new deep outfall system achieves much higher dilutions than the old cliff base system and that initial dilutions are higher than the engineering specifications. ills

[en] HIFAR (High Flux Australian Reactor) is a heavy water moderated and cooled, materials testing and research reactor producing a maximum thermal neutron flux of 10¹⁴ neutrons per square centimeter per second at a heat output of 10 megawatts. It is one of six similar research reactors designed in the United Kingdom in the 1950s and known as the DIDO class. HIFAR operates on a 28-day cycle - 24 days working and four days shutdown to carry out routine maintenance, check safety mechanisms and load fresh fuel. Rigorous maintenance, upgrading and refurbishment have been the key to keeping HIFAR in top condition. Another important factor has been the regular and very carefully implemented longer shutdowns for major maintenance and upgrading work. Top priorities for the 1991 extended shutdown summarized in this issue include: upgrading the total heavy water inventory, inspecting and cleaning the reactor main tank, installing three new collimators for neutron beam experiments and improving facilities for transmutation doped silicon production. The program also included improving the reactor's capabilities in neutron beam research and neutron transmutation doped silicon production. Further tasks carried out were cleaning and repair of main heat exchanger mesh screens and cleaning and painting the reactor plant room floor. Inspections performed in the 1991 have provided a much clearer picture of the condition of the reactor which have been under routine operation for 32 years. This work was aided greatly by remote camera surveillance techniques which have been refined and upgraded in the period since the last major shutdown. Live testing of the emergency core cooling system confirmed the efficacy of new developments in the emergency cooling. ills

[en] Different isotopes of various elements occur naturally in the environment and their isotopic composition, or enrichment, can be used in the investigation of environmental factors such as: evaporation and transpiration rates; degree of chemical mixing in groundwaters; age of the groundwater; the geological environments. Examples of environmental isotopes used in Ansto's studies are presented. These include tritium uranium-238, uranium-234, radium-226, radium-228, chlorine-36, oxygen-18 and carbon-13. They are used to provide age information, to identify the signature of a particular water type, and identify the occurrence of mixing two or more water types as well as to provide information about travel times and groundwater velocities. Using a combination of hydrogeochemical and isotope techniques, it was possible to investigate solute concentration and flow processes, which will provide essential information to assist in designing and monitoring effective measures to reduce the salinity problem. ills

[en] The radioisotopes produced by the Australia's National Medical Cyclotron for positron emission tomography (PET) are of the chemical elements which make up almost the total mass of the human body, and therefore can participate in all of the body's biochemical reactions. A brief presentation of the main clinical uses for the cyclotron produced radioisotopes is given and it is estimated that PET has the potential to be clinically useful for cancer patients when seeing to determine a tumor's response to treatment and the efficiency of chemotherapy. ills