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Hydrodynamic phenomena in the downcomer during flow rate transients in the primary circuit of a PWR
Ist Teil von
Nuclear engineering and design, 2007-04, Vol.237 (7), p.732-748
Ort / Verlag
Amsterdam: Elsevier B.V
Erscheinungsjahr
2007
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Mixing phenomena observed when the flow rate in a single loop of the primary circuit is changed can influence the operation of pressurized water reactor (PWR) by inducing local gradients of boron concentration or coolant temperature. Analysis of one-dimensional Laser Doppler Anemometry (LDA) measurements during the start-up and shutdown of pump on a single loop of the ROCOM test facility has been performed. The effect of a step change and a ramped change in the flow rate on the axial and azimuthal velocities was examined. Numerical simulations were also performed for the step change in the flow rate that gave quantitative agreement with the axial velocities. Phenomenological agreement was made on the turbulent kinetic energy; however, observed values were a factor of 2.5 less than the turbulent kinetic energy derived from the measurements.