CALCULATION OF THE CHANGE IN POWER DISTRIBUTION AROUND THE JOINING STRUCTURE OF THE ABSORBER AND FUEL PART OF THE WWER-440 CONTROL ASSEMBLY USING MCNP5 CODE

Gabriel Farkas, Vladimír Slugeň, Tomáš Melo, Slovakia, Slovak University of Technology

18th Symposium of AER on VVER Reactor Physics and Reactor Safety (2008, Eger, Hungary)
Core operation, Experiments and Code Validation

Abstract

The WWER-440 control assemblies have significant influence on space power distribution (fission rate) and can cause power peaks in adjacent fuel assemblies. This is a consequence of a deficiency in design of joining structure of the absorber adapter to the fuel part of the control assembly, due to presence of water cavity in this space. Presence of the given cavity results in flash-up of thermal neutrons flux density in periphery fuel pins of the adjacent operating fuel assemblies, that is, power gradients can occur inside the mentioned fuel pins that could result in static and cyclic loads with some consequences, e.g. fuel pin bowing.

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