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NKS Programme Area:NKS-R
Research Area:Thermal hydraulics
Report Number:NKS-393
Report Title:Modelling of a Large Water Pool during Operation of Blowdown Pipes, Spargers, and Nozzles
Activity Acronym:COPSAR
Authors:Ignacio Gallego-Marcos, Walter Villanueva, Pavel Kudinov,
Abstract:In a Boiling Water Reactor, steam released from primary coolant system is condensed in the pressure suppression pool. Thermal stratification in the pool affects pressure suppression capacity of the pool. Heat and momentum sources generated by the steam condensation define pool behavior. Direct Contact Condensation (DCC) of steam present a challenge for contemporary modeling tools. In previous work, the Effective Heat Source (EHS) and Effective Momentum Source (EMS) models were proposed to simulate development of thermal stratification or mixing induced by steam injection into a large pool of water. These models are computationally efficient and sufficiently accurate in resolving the effect of DCC phenomena on the large scale pool circulation. EHS/EMS models for blowdown pipes have been extended to predict the transition between condensation regimes, estimate the effective momentum of chugging, allow capturing non-uniform condensation along the pipe, and modelling the drywell and wetwell during prototypic LOCA conditions. Validation against the POOLEX-MIX 04 experiment shows very good agreement with the pool temperature and containment pressure. In the spargers, the experimental data has been analyzed to identify the most important physical phenomena to be considered in the CFD modelling. Based on this analysis, EHS/EMS models for spargers have been developed and implemented in ANSYS Fluent, and validated against the PANDA HP5-1 and 2 experiments. Comparison to pool temperature shows good agreement with the model predictions.
Keywords:Thermal Stratification, Mixing, Pressure Suppression Pool, Spargers, Mixing Nozzles, Containment, Thermal Hydraulic, GOTHIC, BWR
Publication date:21 Aug 2017
ISBN:ISBN 978-87-7893-481-9
Number of downloads:75
Download:pdf NKS-393.pdf

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