Browsing by Author "Jostsons, A"
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- ItemCalibration of a JSEM-200 electron microscope(Australian Atomic Energy Commission, 1975-10) Blake, RG; Jostsons, A; Kelly, PMThe results of a detailed calibration of a JSEM-200 scanning transmission electron microscope are reported. Two types of measurements have been made: (a) calibration of the various parameters associated with scanning transmission (STEM) imaging, and (b) calibration of the usual parameters required for analytical diffraction contrast experiments in the conventional transmission mode (CTEM). The report also contains a detailed discussion of the various STEM imaging modes and the microscope settings necessary to obtain the required image.
- ItemCalibration of a JSEM-200 electron microscope with a magnetic specimen pole-piece(Australian Atomic Energy Commission, 1980-02) Blake, RG; Jostsons, AThis report contains the results of a detailed calibration of the JSEM-200 scanning transmission electron microscope operated with a magnetic specimen pole-piece as supplied by JEOL (Japan Electron Optics Laboratory) Ltd. The microscopy, in this configuration, permits convenient examination of ferromagnetic specimens in the side-entry goniometer specimen stage with a point-to-point resolution better than 2.0 nm.
- ItemCharacterisation of neutron irradiation damage in zirconium alloys - a 'round robin' experiment(Australian Atomic Energy Commission, 1977-01) Blake, RG; Jostsons, AThe nature of the damage structure in the neutron-irradiated zirconium specimens supplied as part of an international 'Round Robin1 experiment has been studied using transmission electron microscopy. The damage structure consists entirely of a/3 <1120> dislocation loops and no evidence has been found for c_ component loops. Both vacancy and interstitial loops were found in specimens where inside/outside contrast analysis was possible. Quantitative measurements of loop size distributions and loop concentrations are reported. All specimens exhibited corduroy contrast to varying degrees.
- ItemCharacterization and leaching behavior of plutonium-bearing Synroc-C(Materials Research Society, 1997-04-22) Smith, KL; Lumpkin, GR; Blackford, MH; Hambley, M; Day, RA; Hart, KP; Jostsons, ASynroc-C containing 10wt% simulated PW-4b-D HLW including 0.62 wt% 239Pu was subjected to MCC-1 type leach tests at 70°C in deionised water, silicate and carbonate leachates for 53 d and deionised water for 2472 d. The normalised total (i.e. unfiltered leachate + vessel wall) Pu leach rates in deionised water, silicate and carbonate leachates for periods up to 53 d were found to be of the order of 10-5, 10-4 and 10-4 g m-2 d-1 respectively. After 2472 d, the differential, normalised, Pu leach rate in deionised water dropped to ∼5 × 10-6 (total) and ∼5 × 10-8 (solution - after filtration through a 1000NMW filter) g m-2 d-1. SEM and AEM were used to characterise our starting material and investigate the secondary phases on the surfaces of leached Synroc-C discs. Calculated and measured normalised Pu leach rates are compared and the partitioning of Pu between zirconolite and perovskite is discussed. © Materials Research Society 1997
- ItemCharacterization and leaching behavior of plutonium-bearing Synroc-C(Cambridge University Press/Springer Nature, 1996-02-05) Smith, KL; Lumpkin, GR; Blackford, MG; Hambley, M; Day, RA; Hart, KP; Jostsons, ASynroc-C containing 10wt% simulated PW-4b-D HLW including 0.62 wt% 239Pu was subjected to MCC-1 type leach tests at 70°C in deionised water, silicate and carbonate leachates for 53 d and deionised water for 2472 d. The normalised total (i.e. unfiltered leachate + vessel wall) Pu leach rates in deionised water, silicate and carbonate leachates for periods up to 53 d were found to be of the order of 10-5, 10-4 and 10-4 g m-2 d-1 respectively. After 2472 d, the differential, normalised, Pu leach rate in deionised water dropped to ∼5 × 10-6 (total) and ∼5 × 10-8 (solution - after filtration through a 1000NMW filter) g m-2 d-1. SEM and AEM were used to characterise our starting material and investigate the secondary phases on the surfaces of leached Synroc-C discs. Calculated and measured normalised Pu leach rates are compared and the partitioning of Pu between zirconolite and perovskite is discussed. © Materials Research Society 1997
- ItemComparative study of Synroc-c ceramics produced by hot-pressing and inductive melting(Materials Research Society, 1997) Sobolev, IA; Stefanovsky, SV; Omelianenko, BI; Ioudintsev, SV; Vance, ER; Jostsons, AThree Synroc-C samples, containing simulated high level waste were studied. One was produced by the conventional hot-pressing method at ANSTO, Australia, and the others were obtained using cold crucible technology at Radon, Russia. One of the melted samples was prepared using the Australian sol-gel precursor and the second one was obtained from an oxide-nitrate mixture. It was established that the specimens have closely similar mineral compositions, with major hollandite, perovskite, zirconolite, and rutile. Small amounts of hibonite were also found. Unlike the hot-pressed Synroc containing metallic alloy particles, melted Synrocs contain molybdates. An investigation of mineral compositions and elemental distribution in the samples was carried out. Features of hot-pressed and melted ceramics were compared. Unit cell parameters of the Synroc phases were determined and preliminary results on durability of the melted Synroc are presented. © Materials Research Society 1997
- ItemCrystallographic techniques and data for transmission electron microscopy of zirconium(Australian Atomic Energy Commission, 1970-02) Jostsons, A; Napier, JGThe crystallography of hexagonal close packed metals is discussed briefly in terms of the four-axis hexagonal reference basis and the Miller-Bravais notation which are used throughout the report. Electron diffraction problems are treated with reference to the four-axis hexagonal reciprocal lattice rather than the more usual three-axis hexagonal system. Using these concepts, analysis of electron diffraction spot and Kikuchi patterns is illustrated and applied to orientation and dislocation Burgers vector determinations. Computed values of interplanar spacings, interplanar angles, angles between directions, and extinction distances for zirconium are listed.
- ItemDissolution of Synroc in deionised water at 150°C(Materials Research Society (MRS)/Cambridge University Press/Springer Nature, 1996-02-15) Smith, KL; Colella, M; Thorogood, GJ; Blackford, MG; Lumpkin, GR; Hart, KP; Prince, KE; Loi, E; Jostsons, ASynroc containing 20 wt% simulated high level waste (HLW) was subjected to two sets of leach tests at 150°C where the leachant was and was not replaced during the test (replacement and non-replacement testing). The leachant was a KH-phthalate buffered solution (pH 4.2). Samples were characterised before and after leach testing using SEM, AEM and SIMS. Elemental concentrations in leachates were measured using ICP-MS. In concert with the findings of i) a dissolution study of perovskite in a flowing leachant and ii) a previous Synroc dissolution study (wherein Synroc containing 10 wt% simulated HLW was subjected to periodic replacement, leach testing in deionised water at 150°C), the results of this study show that when the leachant replacement frequency is varied from 7 d to the duration of the test, there is no effect on leach rate or leaching mechanisms. © Materials Research Society 1997
- ItemLife assessment and extension of HIFAR(The Institution of Engineers Australia, 1994-05-01) Jostsons, A; McDonald, NR; Moss, CJHIFAR has now operated safely for more than 30 years, well beyond the original design expectations, with excellent availability for research and production of radioisotopes. The main reason for the longevity of HIFAR is the degree of conservatism of the design in the 1950's. The key components that affect the estimate of the useful life of HIFAR are presented. They include: the reactor aluminium tank (RAT), the graphite reflector and the reactor steel tank (RST) and shield cooling coils. An assessment of these components indicates that there are no foreseeable technical limitations to the operating life for the continued operation of HIFAR to 2025 at 10MW, in full compliance with safety requirements, provided that attention is paid to operating regimes, regular maintenance and replacement of other components. The costs of refurbishment of HIFAR and its facilities to the year 2025 are considerable. The paper concludes that the main risk from life extension is economic.
- ItemPositron annihilation in neutron irradiated aluminium(International Institute of Welding, 1976-08-23) Pollock, JTA; Jostsons, AThe angular correlation of positron annihilation radiation has been measured from a series of high purity, Polycrystalline, aluminium samples irradiated by neutrons to fluences in the range of 1023-1026 neutron m-2 (E . 0.1 MeV) at 55°. Changes in the annihilation characteristics are attributed primarily to voids formed as a result of irradiation. Data are presented for the sensitivity of angular correlation technique as a measure of the swelling which accompanies irradiation.
- ItemRadiation damage in zirconium(International Institute of Welding, 1976-08-23) Jostsons, A; Blake, RG; Kelly, PMA transmission electron microscopy study if the defect structure in neutron irradiated zirconium has shown the existence of mixed vacancy/interstitial dislocation loop populations with a/3 <1120> Burgers vectors. The absence of c component dislocation loops indicates clearly that the Buckley model for irradiation growth in neutron irradiated zirconium is invalid.
- ItemA report to NERDDP on project no. 1319 entitled : description of synroc durability: kinetics and mechanisms of reaction(Australian Nuclear Science and Technology Organisation, 1990-08) Jostsons, A; Smith, KL; Blackford, MG; Hart, KP; Lumpkin, GR; McGlinn, PJ; Myhra, S; Netting, A; Pham, DK; Smart, RStC; Turner, PSThis is the technical report to NERDDP on Project 1313, "Description of Synroc Durability: Kinetics and Mechanisms of Reaction". Many physical and chemical processes occur, slightly and concurrently, when Synroc is exposed to leachants. A few of these include: * ion-exchange between Synroc and the leachant; * dissolution of some primary phases; * formation of colloids; * precipitation of secondary phases. All of these processes (and others) affect the durability of Synroc. Consequently, it has been necessary to apply an armoury of techniques, to unravel the various processes and their effects. Techniques used include: * solution analysis by inductivity coupled plasma mass spectrometry (ICP/MS) and inductivity coupled plasma optional emission spectroscopy (ICP/OES); * scanning and analytical transmissions electron microscopy (SEM and AEM respectively); * X-ray photoelectron spectroscopy (XPS) and Auger spectroscopy. We have matched or exceeded all the sub-objectives agreed to and funded by NERDDP in 1989/90. Furthermore we have begun to integrate the information generated under the auspices of the grant as well as information subsequently collected, into a comprehensive model. The information contained within the bulk of this report can be broken down into areas which relate to the sub-objectives of the project.
- ItemStatus of SYNROC development(The Institution of Engineers Australia, 1994-05-01) Jostsons, AThe SYNROC strategy for the High Level Waste (HLW) management was proposed in 1978. Since that time extensive evidence for the chemical durability of SYNROC has been obtained from tests with simulated HLW, real radioactive waste and from accelerated alpha-decay damage studies. SYNROC fabrication has also been demonstrated on a commercial (10 kg/hr) scale with non-reactive waste simulants and key process advantages are described. The potential for the utilization of SYNROC together with glass waste forms is discussed briefly in the context of the partitioning of defense wastes and advanced reprocessing strategies for commercial spent fuel management. In particular, strong scientific evidence exists for the serious consideration of SYNROC for the management of excess weapons plutonium if the geological disposed option is pursued in the future.
- ItemTransmission electron microscope procedures for characterising dislocation loops in neutron-irradiated zirconium and its alloys(Australian Atomic Energy Commission, 1976-04) Blake, RG; Jostsons, A; Kelly, PMComplete characterisation of the dislocation loops in irradiated zirconium and its alloys present particular problems; these include unfavourable texture, the presence of thin foil artefacts; the non-edge character of the loops and their elliptical shape. The procedures adopted to deal with these problems are described and a number of precautionary measures are listed. After considering the possible confusion between thin foil artefacts and small defect clusters, the report outlines the characterisation procedure in the order; Burgers vector identification; loop geometry; loop nature; and quantitative measurements. A detailed analysis of the possible errors associated with loop ellipticity is given in Appendix A.