Browsing by Author "Thorogood, KJ"
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- ItemAgeing management program of Kartini reactor for safe operation(International Atomic Energy Agency, 2007-11-05) Nitiswati, S; Syarip, S; Tjiptono, TW; Stathers, PA; Thorogood, KJ; Belvins, RJThis paper discusses the regular inspections of the Kartini reactor tank liner as part of the ageing management program. Kartini reactor is located in Yogyakarta, in Indonesia. The aim of the regular inspections is to assess the reactor tank condition as part of the ageing monitoring program to ensure safe operation of the reactor. The reactor was inspected utilizing a series of non-destructive inspection methods between 2001 and 2006. One of the inspection results was the detection of two swelling features seen on the bottom of the reactor tank. Kartini reactor has been in operation for 28 years and the observed swelling has been monitored over the past 5 years. The regular measurements and observations show that the swelling has stopped increasing in size and has now reached a stable size. After assessment and analysis of the cause of the swelling the reactor is considered to be in good condition and safe for future operation. © The Authors
- ItemThe effect of laser cladding deposition rate on residual stress formation in Ti-6Al-4V clad layers(Trans Tech Publications, 2012-08) Cottam, R; Thorogood, KJ; Lui, Q; Wong, YC; Brandt, MThe effect of deposition rate on the residual stresses formed during the laser cladding of Ti-6Al-4V powder onto a Ti-6Al-4V substrate was investigated. To isolate the deposition rate from the heat input an analytical laser cladding model was employed to control the melt pool depth to 0.1mm. The clad height was also held constant by the model at 1mm. The laser traversing speed was varied between 300 and 1500 mm/min. The residual stresses were measured using the contour method and it was found that the distribution of residual stress was similar for the different deposition rates and that there was a small variation in the tensile stress level reached in the clad and heat affected zone (HAZ) layer. The microstructures for all three clad layers were a’ martensite and the size of the HAZ was consistent from sample to sample. It was concluded that residual stress development is independent of deposition speed for the laser cladding of Ti-6Al-4V. © 2025 Trans Tech Publications Ltd.
- ItemEffect of welding thermal cycle on the microstructure of Zircaloy-4(International Institute of Welding, 2009-07-16) Thorogood, KJ; Li, HJ; Carr, DG; Harrison, RP; Nolan, DZirconium and its alloys are important materials commonly utilised in the nuclear industry, primarily due to their low neutron absorption cross-section and excellent corrosion resistant properties. Zircaloy-4 is one of the most widely used nuclear grade zirconium alloys and contains primary alloying elements of tin, iron, chromium and oxygen. Typical applications include structural core components and fuel cladding. Fully welded structures such as heavy water reflector vessels have been fabricated from Zircaloy-4. Although the structure-property relationships of Zircaloy-4 parent metal and weld metal is well understood, there is limited understanding of the same relationship for the narrow weld heat-affected zone. The work reported in this paper is an investigation of the influence of the weld thermal cycles on the microstructure and texture of Zircaloy-4 heat-affected zone material. Discrete regions within the heat-affected zone were simulated using a thermo-mechanical simulator (Gleeble 3500). Peak temperatures of the thermal cycles studied were 1000,1200, 1400 and 1600°C. Weld simulation has been shown to produce a volume of material sufficient for analysis and which represents the individual sub-zones. © 2010, International Institute of Welding
- ItemInvestigation of residual stresses in titanium aerospace components formed via additive manufacturing(Engineers Australia, 2014-01-01) Hoye, N; Li, HJ; Cuiuri, D; Paradowska, AM; Thorogood, KJIn the present study gas tungsten arc welding (GTAW) with automated wire addition was used to additively manufacture (AM) a representative thin-walled aerospace component from Ti-6Al-4V in a layer-wise manner. Residual strains, and hence stresses, were analysed quantitatively using neutron diffraction techniques on the KOWARI strain scanner at the OPAL research facility operated by the Australian Nuclear Science and Technology Organisation (ANSTO). Results showed that residual strains within such an AM sample could be measured with relative ease using the neutron diffraction method. Residual stress levels were found to be greatest in the longitudinal direction and concentrated at the interface between the base plate and deposited wall. Difficulties in measurement of lattice strains in some discrete locations within the deposited material were ascribed to the formation of localised grain orientation where α-Ti laths form in aligned colonies within prior β-Ti grain boundaries upon cooling. Neutron diffraction measurements of residual stress were cross-correlated using the contour method with results found to be in close agreement. Observations of microstructure reveal 'basket-weave' morphology typical of fusion welds in Ti-6Al-4V. Microhardness measurements show lower hardness in the deposited material compared to the base plate and a further small decrease in hardness in the top region of the deposit, indicating a dependence on thermal cycling from sequential weld deposition. © 2021 Informit
- ItemOxygen deficient lead-technetium pyrochlore, the first example of a stable valence V technetium oxide?(European Association of Geochemistry and the Geochemical Society (Goldschmidt), 2021-07-05) Thorogood, GJ; Avdeev, M; Carter, ML; Losurdo, L; Saura-Múzquiz, M; Thorogood, KJ; Ting, J; Wallwork, KS; Zhang, Z; Kennedy, BJDespite the fact that Technetium V oxides are possible there are very few reports of their existence. Most recently Lawler et.al. [1] have reported the structure of Tc2O5 “tech red” and have noted that it is indeed volatile. It is apparent from this study that there is no stable form and they draw parallels with a well-studied analogue of Tc2O5, Re2O5 that disprortioniates into Re(4+) and Re(7+) species. Given these parallels we investigated PbTcO3 as reported by Muller et.al [2] to be a pyrochlore in an attempt to determine if there were parallels with Pb2Re2O7-d. The structure of lead-technetium pyrochlore has been refined in space group with a = 10.36584(2) Å using a combination of synchrotron X-ray and neutron powder diffraction data and confirmed via Electron Diffraction. The oxide is found to be oxygen deficient with a stoichiometry of Pb2Tc2O6.86. The displacive disorder of the Pb cations is evident from the refinements as has been observed Bi2Tc2O7-d. X-ray absorption measurements at the Tc K-edge demonstrate the valence of the Tc is greater than 4.0 as anticipated from the refined oxygen stoichiometry. Raman spectroscopy confirms the local coordination of the Technetium leading us to conclude that this pyrochlore is the first example of a stable valence V Technetium oxide. [1] Lawler, K. V. et al. Unraveling the mystery of ‘tech red’-a volatile technetium oxide. Chem. Commun. 54, 1261–1264 (2018). [2] Muller, O., White, W. B. & Roy, R. Crystal chemistry of some technetium-containing oxides. J. Inorg. Nucl. Chem. 26, 2075–2086 (1964).
- ItemResidual stress in metal-matrix composite cylinder measured by neutron diffraction and contour method(Materials Research Forum LLC, 2016-07-03) Luzin, V; Thorogood, KJ; Griffiths, JR; Davidson, CJ; Finlayson, TRA cylindrical sample, 14.8 mm in diameter, was machined from an Al-Mg-Si casting and then heat-treated. For the purposes of this research, the casting can be regarded as a two-phase composite of aluminium and 6 vol.% of near-spherical Si particles ~3 μm in diameter. Residual stresses in the cylinder are (i) long-range macrostresses resulting from the transient temperature gradients formed during heat-treatment, and (ii) short-range microstresses resulting from differences in the coefficients of thermal expansion between Al and Si. Neutron diffraction has been used to measure the stress tensors in each phase of the composite as a function of radial position with 2 mm spatial resolution and the microstress and macrostress components have been successfully separated. The contour method was applied to measure the axial component of the macrostress and the results are in good agreement with the neutron diffraction data. © The Authors
- ItemThe role of metallurgical solid state phase transformations on the formation of residual stress in laser cladding and heating(Trans Tech Publications, 2014-02) Cottam, R; Luzin, V; Thorogood, KJ; Wong, YC; Brandt, MThere are two major types of solid state phase transformations in metallic materials; the formation of second phase particles during heat treatments, and the transformation of the matrix from one crystalline packing arrangement to another during either heating or cooling. These transformations change the spacing between adjacent atoms and can thus influence the residual stress levels formed. The heating and cooling cycles of materials processing operations using lasers such as cladding and melting/heating, can induce phase transformations depending on the character of the material being processed. This paper compares the effects of the different phase transformations and also the influence of the type of laser processing on the final residual stress formed. The comparisons are made between laser clad AA7075, laser clad Ti-6Al-4V and laser melted nickel-aluminium bronze using neutron diffraction and the contour method of measuring residual stress. © 2014 Trans Tech Publications.
- ItemRoot cause analysis of swelling problem in Kartini Reactor(International Atomic Energy Agency, 2007-11-05) Syarip, S; Nitiswatia, S; Sardjono, Y; Sutondo, T; Tjiptono, TW; Stathers, PA; Belvins, R; Thorogood, KJRoot cause analysis (RCA) is applied for the swelling problem in the Kartini reactor. The RCA result shows that probable root cause of swelling are as follows: It is probable that the seal on the cover plate in the service pool has deteriorated and allowed water to enter both the thermal column and the space between the aluminium reactor pool liner and the concrete. The water will also saturate the concrete and has the potential to corrode the steel reinforcement close to the surface of the concrete. It is believed that water leakage from the service pool has entered the area behind the aluminium pool liner and has saturated the concrete. It is believed that carbon steel reinforcement close to the inner surface of the reactor block has corroded. The expanding corrosion product (rust) has the forced layer of concrete covering the steel reinforcement and subsequently pushing the aluminium pool liner inwards, causing the swelling. There are two issues: the mechanism for the creation of the swellings or bulges dominated by Iron corrosion, and the potential for corrosion of aluminium dominated by the pH of water in contact with the aluminium. As the evidence for this condition were: the apparent corrosion of steel reinforcement behind aluminium liner and formation of Ca(CO3) on outside of concrete reactor block indicating water saturation of the concrete block. The condition is advancing and will most probably result in a loss of pool liner integrity, this may or may not result in a loss of pool water due to the concrete backing behind the pool liner. Based on the above analysis, the remedial actions that can be considered are as follows: The pool liner would be patched with a welded panel that would allow the features we have observed to keep growing in a harmless way. It is expected that they will reach a finite size as the iron is consumed by corrosion. The area behind the pool liner would be dried out, this should limit further growth of the bulges by improving the corrosion conditions behind the pool liner. The bulk storage facility would be lined with stainless steel (the potential to use the thermal column could be preserved for future use). This would remove what is thought to be the root cause of the bulges and keep the reactor block dry. © The Authors
- ItemSynthesis and structure of oxygen deficient lead-technetium pyrochlore, the first example of a valence V technetium oxide(Frontiers Media, 2021-07-01) Kennedy, BJ; Ablott, TA; Avdeev, M; Carter, ML; Losurdo, L; Saura-Múzquiz, M; Thorogood, KJ; Ting, J; Wallwork, KS; Zhang, ZM; Zhu, HL; Thorogood, GJThe structure of lead-technetium pyrochlore has been refined in space group F d 3 ¯ m with a = 10.36584(2) Å using a combination of synchrotron X-ray and neutron powder diffraction data and confirmed via Electron Diffraction. The oxide is found to be oxygen deficient with a stoichiometry of Pb2Tc2O7-d. Displacive disorder of the Pb cations is evident from the refinements, as has been observed in Bi2Tc2O7-d. X-ray absorption spectroscopic measurements at the Tc K-edge demonstrate the valence of the Tc is greater than 4.0 as anticipated from the refined oxygen stoichiometry. Raman spectroscopy confirms the presence of disorder leading us to conclude that this pyrochlore is the first example of a valence V technetium oxide. © 2021 Kennedy, Ablott, Avdeev, Carter, Losurdo, Saura-Muzquiz, Thorogood, Ting, Wallwork, Zhang, Zhu and Thorogood. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).