Browsing by Author "Dias, MP"

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    An analytical solution to time-dependent fission-product diffusion in an HTGR core
    (Elsevier, 1985) Lee, CE; Head, JG; Dias, MP
    An analytical time-dependent fission-product diffusion model is solved for the fuel-moderator regions of a high temperature gas-cooled reactor (HTGR) during a hypothetical loss of forced circulation (LOFC) accident. A conservative approximate 1-D model is developed for the fuel and moderator regions, represented in cylindrical and slab geometries, from consideration of the hexagonal fuel-element symmetry. Transport is assumed along the shortest diffusion path and the concentration change across the fuel-moderator interface is approximated by a jump condition. The model is solved by construction of the Green's functions for the Laplace-transformed equations and identification of the pole structure. The concentration and current inverse Laplace transforms are obtained by the Cauchy residue theorem in each region for cubic piecewise polynomial initial conditions. A computer program was developed and validated to evaluate the solution, serve as a benchmark for more sophisticated numerical models and to investigate 90Sr diffusion during a hypothetical LOFC.
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    Analytical solutions to the moment transport equations--i : One-group one-region slab and sphere criticality
    (Pergamon Press Ltd, 1984) Lee, CE; Dias, MP
    Analytical PN and AN moment criticality solutions are obtained for uniform infinite slabs and finite spheres using Mark, Marshak and importance-weighted vacuum boundary conditions. Comparison with 'exact' criticality results leads to reevaluation of the literature-reported 'belief' in the relative accuracy comparisons of Mark and Marshak boundary conditions. The ranking for these problems is Mark, Marshak, importance-weighted in order of increasing accuracy.
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    A dc link for the power system simulator
    (Electrical Engineering Society (EESoc) of Department of Electrical Engineering, University of Moratuwa, 2015-12) Abeyrathne, PM; Abeysinghe, AMGT; Karunanayake, IM; Ranasinghe, PMH; Dias, MP; Lucas, JR; Jayasekara, AGBP
    High Voltage Direct Current (HVDC) links are used for bulk power transmission due to its advantages over the alternating current (ac) transmission. A HVDC link between India and Sri Lanka has also being proposed. Hence it is a timely needfor the students in local universitiesto be able to study the behaviour of HVDC transmission. This paper presents the design of a DC link for a locally assembled Power System Simulator as a teaching tool.The objective is to use this design as a learning tool to study the behaviour of HVDC transmission under normal and abnormal operation. It is expected to be used for laboratory experiments related to HVDC transmission and Power Electronics, hence providing the opportunity for visualization of the behaviour of performance parameters at the significant points of the model.