Conference Proceedings Paper
A MATLAB Computational Tool for Modelling Mo-99-Producing CANDU Bundles
37th Annual CNS-CNA Student Conference - 2013 June 11
Nicholas Chornoboy (UOIT)
Kyle Croucher (UOIT)
Alexander Edwards (UOIT)
Mark Lam (UOIT)
Adam Waters (UOIT)
Eleodor Nichita (UOIT)
Mo-99 is an important radionuclide for clinical diagnostic applications, as it is used to produce Tc-99m. Mo-99 is produced primarily in research reactors as a fission product of U-235. The NRU reactor in Chalk River produces approximately half of the worldÕs supply of Mo-99, but it is scheduled to cease production in 2016. One possible production alternative is to use specially-designed Mo-99-producing bundles in CANDU reactors. The design of such bundles involves altering some of the parameters of the regular CANDU bundle (e.g. enrichment, fuel-pin diameter, etc.), with implications on the power distribution between different fuel rings, fuel temperature and Mo-99 production in each fuel ring. In the initial design phase, it is customary to investigate a relatively large number of bundle configurations and the implications of different design options. For such preliminary design activities, as well as for teaching purposes, it is useful to have a tool able to predict the quantities of interest with minimal computational effort, even at moderate accuracy. This work presents the development of a customized computational tool which can calculate the infinite multiplication factor, pin power distribution, fuel centerline temperature and Mo-99 yield for a CANDU-type bundle for different fuel pin radii, pitch circle radii and fuel enrichment. The tool is developed in MATLAB. It uses a Wigner-Seitz equivalence between a square lattice cell and a circular one, which is subsequently analyzed using one-dimensional diffusion in cylindrical geometry. The diffusion equation is discretized using finite differences. Inverse power iteration is used to calculate the multiplication constant and flux in each fuel ring. The flux, in turn, is used to calculate the power, fuel temperature and Mo-99 production in each fuel ring.
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