05 Nuclear fuels (scientific, technical)
incorporates a digital signal processor and a system-on-chip device which performs the data transfer, the device control/monitoring and may perform statistical, data reduction or control algorithms in real- time.
04•02759 An analysis of convective dispersion and reaction in the fixed-bed reactor Gunn, D. J. International Journal o f Heat and Mass TransJer, 2004, 47, (12-13), 2861 2875. The physics of dispersion in fixed beds of randomly-placed particles are considered against the background of experimental and theoretical work published during the past several years. The general equations for the reactor are shown as developments of the Central Limit Theorem, that may be presented as a second order equation defined by two-point boundary conditions. When dispersion is convective it is shown that the boundary conditions may be transformed into initial conditions and a numerical solution, if required, may be obtained without iteration. Illustrations of the method are given for non-linear processes including single and non-isothermal reactions. The application of the method to multiple reactions is described.
04/02760 An injector device for producing clean-surface liquid metal samples of Li, Ga and Sn-Li in vacuum Baldwin, M. J. et al. Fusion Engineering and Design, 2004, 70, (2), 107 II3. A vacuum-compatible-injector device, that allows the extrusion of clean-surface samples of low-melting-point liquid metal into a holder kept in vacuum, is reported. Clean-surface samples of liquid lithium, gallium and 80 at.% tin-20 at.% lithium alloy have been demonstrated for the purpose of their use in plasma/liquid metal interaction experiments. As a result of the use of the injector, subsequent experiments are free of the influences of surface-oxide material. The elimination of surface oxide facilitates wetting and spreading of clean- liquid lithium on a stainless steel substrate holder (AISI 304). Further, the spreading of the liquid is more rapid with increasing holder temperature. At temperatures above 500°C, evaporative loss of the lithium is substantial under vacuum conditions. However, pressurizing the vacuum system with argon gas to approximately 1 atm significantly suppresses evaporation while maintaining chemically-inert conditions that keep the lithium clean, and facilitate a reasonable wetting rate.
04•02761 Bulk and Young's modulus of doped UO2 by synchrotron diffraction under high pressure and Knoop indentation Pujol, M. C. et al. Journal of Nuclear Materials, 2004, 324, (2-3), 189 197. The elastic constants of doped UO2 simulating a burn-up in the reactor of up to 200 GWd/t M (N20% U-atoms replaced by fission products) were measured by synchrotron diffraction under high pressure and by Knoop indentation. As a complement, also the corresponding thermal expansion was determined by X-ray diffraction at high temperature. It is shown that the elastic constants of the simulated fuels are increased with burn-up, while the thermal expansion is decreased, satisfying the Gr(ineisen equation. An increasing Grfineisen constant ~ with burn-up is also suggested. The results are, however, in contradiction with empirical bulk modulus estimates and previous data from ultrasonic measurements indicating either slightly decreasing or unchanged to strongly decreasing stiffness with burn-up. The need to perform detailed cohesive energy calculations of the doped fuel (ab initio or empirical potential methods), as well as to review the role of microstructure heterogeneities in the ultrasonic E-modulus determi- nations are therefore suggested.
04/02762 Cathodoluminescence imaging of oxidised zirconium alloys Yueh, H. K. and Cox, B. Journal of Nuclear Materials, 2004, 324, (2 3), 203-214. Cathodoluminescence (CL) imaging techniques have been applied to the characterization of the zirconium oxide films formed from binary Zr alloy matrices using a homemade CL imaging system attached to an Hitachi S-570 scanning electron microscope (SEM). Evidence from the CL images shows the involvement of the individual Zircaloy alloying elements in the luminescence process. /3-annealed and slow-cooled samples which have strongly segregated alloying elements at their grain boundaries showed strong CL signals from these areas. Use of this heat treatment was necessary to compensate for the low resolution of the equipment. Strong CL signals were observed also from cracks in the oxides on some alloys and are believed to be caused by the redistribution of iron to the region adjacent to the crack, but below the original surface. Increasing redistribution of Fe with increasing oxidation temperature is seen in the CL images. The cyclic behaviour observed in the weight gain measurements is also observed in the CL intensity measurements. Experimental data from this investigation
392 Fuel and Energy Abstracts November 2004
support the theory that this phenomenon is caused by the successive formation of cracks parallel and normal to the plane of the metal matrix.
04•02763 Chemical form of tritium released from solid breeder materials Nishikawa, M. et al. Journal o f Nuclear Materials, 2004, 325, (2 3), 87- 93. The fraction of HTO in total tritium was measured at release of the bred tritium to the purge gas with hydrogen using the thermal release after irradiation method, where neutron irradiation was performed at the Japan Research Reactor-3 (JRR-3) in Japan Atomic Energy Research Institute (JAERI) or the Kyoto University Research Reactor (KUR reactor) in Kyoto University. It is experimentally confirmed in this study that not a small portion of bred tritium is released to the blanket purge gas in the form of HTO from ceramic breeder materials even when hydrogen is added to the purge gas. Observation in this study implies that it is necessary to have a bred tritium recovery system useful for both HT and HTO form tritium. The water formation properties from Li2TiO3 bed placed in the hydrogen atmosphere were also discussed in this study.
04•02764 CompactPCI/Linux platform for medium level control system on FTU Wang, L. et al. Fusion Engineering and Design, 2004, 71, (1-4), 23-28. In large fusion experiments, such as tokamak devices, there are common trends for slow control systems. Because of complexity of the plants, several tokamaks adopt the so-called 'standard model' (SM) based on a three-level hierarchical control: (i) high level control (HLC) - the supervisor; (ii) medium level control (MLC)-I/O field equip- ments interface and concentration units and (iii) low level control (LLC) - the programmable logic controllers (PLC). FTU control system was designed with SM concepts and, in its 15 years life cycle, it underwent several developments. The latest evolution was mandatory, due to the obsolescence of the MLC CPUs, based on VME/Motorola 68030 with OS9 operating system. Therefore, cost-effective solutions were needed and a CompaetPCI-Intel x86 platform with Linux operating system chosed. A software porting has been done taking into account the differences between OS9 and Linux operating system in terms of inter/network processes communications and I/O multi- ports serial driver. This paper describes the hardware/software architecture of the new MLC system emphasizing the reliability and the low costs of the open source solutions. Moreover, the huge amount of software packages available in open source environment will assure a less painful maintenance, and will open the way to further improve- ments of the system itself.
04•02765 Comparison between HELIOS critical-depletion calculations and a PWR thorium cell burnup benchmark Ntifiez-Carrera, A. et al. Annals of Nuclear Energy, 2004, 31, (7), 713- 722. A comparison between the HELIOS computer code and a pin cell burnup benchmark is presented in this paper. The benchmark is based on a thorium fuel pin cell moderated with light water. The burn-up dependent eigenvalue and isotopes concentrations obtained with HELLOS were compared with those obtained with state-of-the-art transport codes (MOCUP, INEEL-MOCUP and CASMO4). The pin cell model considers eight azimuthal regions in the moderator zone and two radial regions in the fuel. The analysis with HELLOS was carried out with cross-section libraries of 35 and 190 energy groups. The HELLOS results showed that the average absolute difference as a function of burnup were less than 1% 6k/k in the eigenvalue and an average absolute difference of around 5% in the isotopes concen- tration, with respect to CASMO4 code.
04•02766 Creep surge effect under cyclic irradiation of structural materials for fusion reactors Tsepelev, A. B. Fusion Engineering and Design, 2004, 70, (2), 79-85. Experimental investigations were performed on the radiation-creep behavior of austenitic stainless steels, c~-Fe and Fe-Cr alloys. The effect of an abrupt increase of creep rate early after either switching on and switching off irradiation (radiation-induced creep surge) was revealed. The effect of electron irradiation on the thermal-activation parameters of creep was examined. The radiation creep surge effect is discussed in terms of a dynamic preference of dislocations under nonstationary conditions typical of the formation of new radiation- equilibrium flows of radiation induced point defects.
04/02767 Development of core fuel management code system for CANDU reactor based on coupled neutronics and thermal-hydraulic advanced nodal method Huo, X. et al. Annals of Nuclear Energy, 2004, 31, (10), 1083-1100. In this paper, a fuel management programme for pressurized heavy water reactor (FMPHWR) based on advanced three-dimensional nodal method has been developed, which was integrated with thermal
