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Conference Article: An Evaluation of the Control Rod Modelling Approach used in VSOP by Comparing its Results to the Experiments Performed in the ASTRA Critical Facility

F. Reitsma, D. Naidoo and Z. Karriem, Radiation and Reactor Theory, NECSA, Pretoria, South Africa

Abstract

The modelling of strong absorber regions in diffusion theory is a well-known problem and many methods have been developed to accommodate the transport effects in diffusion theory. In this work the method of equivalent cross sections is evaluated for the ASTRA critical facility at the Russian Research Centre – Kurchatov Institute in Moscow. The measured reactivity worths of the control rods situated in the side reflector, are compared with the calculated values making use of equivalent diffusion parameters in VSOP. Favourable results were obtained for the control rods positioned within the first ring of reflector blocks with larger errors obtained for control rods positioned further from the core. Furthermore, the use of an equivalent boron concentration to represent the absorber regions was also investigated and shown to be useful if applied correctly and with care. However, the practical difficulties and restrictions imposed by the two approaches make the investigation of an alternative method, which should remove these shortcomings, attractive.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Proceedings of the Conference on High Temperature Reactors, Petten, NL, April 22-24, 2002
Organized by HTR-TN in cooperation with the European Nucler Society (ENS) and the IAEA
International Atomic Energy Agency, Vienna (Austria)
HTR-2002, pp:1-7