Hydrodynamics and mixing of a coolant in the core of the VVER with fuel assemblies of different designs

The study presents the experimental results for inter-assembly interaction of coolant flows in the core of the VVER consisting of fuel assemblies TVSA-T and TVSA-T.mod.2. The coolant flowing in fuel assemblies (FA) was modeled on an aerodynamic stand. The studies were carried out on the model of the VVER core fragment and consisted in measuring the velocity vector modulus in the characteristic zones of both the TVSA and the inter-assembly space of the VVER core. Measurements were carried out by a five-channel pneumometric probe. The analysis of the spatial distribution of the projections of the absolute flow velocity allowed detailing the pattern of streamlining of the spacer, mixing and combined spacer grids of the TVSA by the coolant flow. Results of investigation of inter-assembly interaction of the coolant between adjacent fuel assemblies TVSA-T and TVSA-T.mod.2 were adopted for practical use in JSC “OKBM Afrikantov” to assess the thermal reliability of VVER cores and included in the database to verify the programs of computational fluid dynamics (CFD-codes) and to provide a detailed cell calculation of the VVER core.