Modeling burnup-induced fuel rod deformations and their effect on transient behavior of a VVER-440 reactor core

Syrjälahti, Elina; Ikonen, Timo; Tulkki, Ville

doi:10.1016/j.anucene.2018.10.039

Cited by 5 publications

(1 citation statement)

References 7 publications

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“…Neutronic modeling of bowing has then received much attention, because of several significant consequences. Those include fuel cycle management (Li, 2017a,b), excore instrumentation (Konheiser, 2016), safety regarding departure from nucleate boiling (Mukin, 2017;Mukin, 2018), rod design evolution (Fetterman, 2008) (since neutronic effect also has in return an actual impact on mechanics, see for instance (Karlsson, 1999;Syrjälahti, 2019)), and more generally core management policies (Kerkar and Paulin, 2008). The range of deformation can lead to 20 mm water gaps within the core (Shishkov, 2015;IAEA, 2008;Fetterman, 2008), representing a reference value used further to validate the proposed models.…”

Section: Introduction Context and Problematicsmentioning

confidence: 99%

Modeling the consequences of fuel assembly bowing on PWR core neutronics using a Monte-Carlo code

Lambert

Campioni

Faucher

et al. 2019

Annals of Nuclear Energy

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The effect of assemblies bowing in PWR nuclear reactors onto core neutronics is an observed phenomenon still poorly understood which can lead to Power Ratio Tilt. Studies of the consequences of rod/assembly bowing involve many different fields addressed by nuclear power plant, such as neutronics, thermohydraulics, mechanics.. . in a complex combination of multi-physical interactions. For the neutronic part, the modeling of bowed assemblies in Monte Carlo codes must allow to correctly describe the shape of fuel rods. In this article, two discrete ways to model bowed geometries are tested: the first one consists in a stacking of vertical small cylinders following the shape of the fuel rod by small shifts between neighboring cylinders; the second one, newly introduced in the present research, consists in a sequence of rotated cylindrical segments arranged to as to follow the shape of the fuel rod more closely. Both models are used to reproduce two specific bowing patterns, namely C-shape and S-shape, for which a reference modeling involving an analytical toroidal volume cut by planes is available for use with CEA's Monte Carlo code Tripoli-4 Ò. Results of comparisons between both models and analytical reference show that, even if the segment modeling requires a specific effort to handle implementation constraints, it appears preferable compared to stacking modeling. It provides accuracy with fewer discrete entities and is therefore computationally affordable and it is far more robust when increasing bowing deflection. This approach is thus only considered ready for its application to any kind of bowing patterns.

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