| 1. |
- Anghel, Ionut Gheorghe, et al.
(author)
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Experimental Investigation of the Influence of Flow Obstacles on Post-Dryout Heat Transfer in an Annulus
- 2009
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In: ICONE 17. - NEW YORK : AMER SOC MECHANICAL ENGINEERS. - 9780791843536 ; , s. 277-286
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Conference paper (peer-reviewed)abstract
- This paper describes the experimental setup, instrumentation and procedures which have been developed in the thermal-hydraulic laboratory at the Royal Institute of Technology (KTH), Stockholm, Sweden, to perform new post-dryout heat transfer investigations in an annulus with flow obstacles. Previous investigations performed in the same laboratory indicated that flow obstacles had a considerable influence on the post-CHF heat transfer. The measured heat transfer enhancement was significantly under-predicted by existing models. However, the net effect of obstacles could not be deduced from the measurements, since reference - obstacle-free measurements- had not been performed. In addition, the number of thermocouples that could be installed inside the heated rod was limited to 8. These deficiencies have been removed in the current approach. Firstly, the present design of the test section allows for measurements both with and without flow obstacles. In this way the net effect of the obstacles will be captured. Secondly, a newly developed technique allowed the installation of 40 thermocouples inside of the heated rod. An additional 40 thermocouples have been installed on the external wall of the heated tube. Therefore, a significant improvement of the accuracy of measurements can be expected. The present arrangement of instrumentation is suitable to perform measurements of heat transfer under both steady-state and transient conditions.
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| 2. |
- Caraghiaur, Diana, 1978-, et al.
(author)
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Verification of Discontinuous Random Walk Lagrangian Particle Tracking as a Tool to Model Deposition in Annular Flow
- 2009
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In: Proceedings of the 17th International Conference on Nuclear Engineering ICONE17 July 12-16, 2009, Brussels, Belgium ICONE17-75297. - Brussels, Belgium. - 9780791843536 ; , s. 311-319
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Conference paper (peer-reviewed)abstract
- A verification of the applicability of the discontinuous random walk (DWR) Lagrangian Particle Tracking (LPT) model to calculate deposition in annular two-phase flow has been conducted. The comparison of simulation results to experimental data of deposition of mono-sized droplets shows that the model follows the correct trend in inertiamoderated regime, but is un-reliable in diffusion-impaction deposition regime. The comparison to other experimental studies of annular flow of different density ratios between the two phases reveals that the density ratio is incorrectly incorporated into the model, since the experimental trend is reversed. It can be concluded that the applicability of DWR LPT model for deposition calculation in steam-water flow at BWR conditions cannot be validated by solely comparing the simulation results to air-water experimental data.
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| 3. |
- Kudinov, Pavel, et al.
(author)
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Development of ex-vessel debris agglomeration mode map for a LWR severe accident conditions
- 2009
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In: ICONE 17. - NEW YORK : AMER SOC MECHANICAL ENGINEERS. - 9780791843536 ; , s. 37-46
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Conference paper (peer-reviewed)abstract
- Ex-vessel debris bed coolability is cornerstone for severe core melt accident mitigation scheme adopted in Swedish type BWRs. Debris agglomeration can significantly affect coolability of the debris bed. The paper discusses an approach for conservative-mechanistic assessment of the debris agglomeration. In order to tackle with considerable aleatory and epistemic uncertainties which present in accident scenario and in the debris agglomeration phenomena we apply mechanistic simulation tool VAPEX code and conservative assumptions about agglomeration related phenomena and accident scenario. Results of systematic analysis arc presented in a form of agglomeration mode map. The map shows conditions for transition between different modes of debris agglomeration. Assessments of the influence of epistemic uncertainties and of numerical discretization errors on simulation result are provided. Safety implication aspects of the proposed agglomeration mode map are discussed in the present paper.
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