3d diffusion calculations of HIFAR including the coarse control arms and their burnup
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Date
1991-09
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Publisher
Australian Nuclear Science and Technology Organisation
Abstract
A 3D model of HIFAR which includes the coarse control arms (CCA) has been developed which is based on a 2-group relatively coarse mesh diffusion calculation. Appropriate absorption cross sections to represent the signal arm control blades were obtained by comparison with multigroup discrete ordinates cell calculations. An integral test of the CCA worth using the model showed excellent agreement with a geometrically detailed Monte Carlo calculation. Comparison with the most recent measurement of the CCA reactivity calibration showed good agreement and in particular a constant difference of about 6 per cent between calculation and measurement in change of reactivity with arm movement over the normal operating range. Extension of the model to include the burn-up of the CCA control material has provided the first calculation-based estimates of the loss of CCA effectiveness with time. Similar estimates of the worth of europium tipped control blades and their lifetime have been made. This confirmed that blades of this type have almost identical initial reactivity worth to all-cadmium blades and that their lifetime is very much longer.
Description
Keywords
Diffusion, HIFAR Reactor, Neutron flux, Mathematical models
Citation
Australian Nuclear Science and Technology Organisation. (1991). 3d diffusion calculations of HIFAR including the coarse control arms and their burnup (ANSTO/E303). Lucas Heights, NSW: Australian Nuclear Science and Technolgy Organisation.