Contact

Dr. Eckhard Krepper
Computational Fluid Dynamics
e.krepperAthzdr.de
Phone: +49 351 260 - 2067
Fax: +49 351 260 - 12067

Dr. Alexander Grahn
Reactor Safety
a.grahnAthzdr.de
Phone: +49 351 260 - 2331
Fax: +49 351 260 - 12331

Numerical and experimental investigations for insulation particle transport phenomena in water flow

The investigation of insulation debris generation, transport and sedimentation becomes more important with regard to reactor safety research for PWR and BWR, when considering the long-term behaviour of emergency core coolant systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb/impinge on the emergency core cooling systems.

Open questions of generic interest are the fibre transport in an aqueous flow, the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow and the fibre load on strainers and the corresponding pressure drop.

A joint research project on such questions is being performed in cooperation of the University of Applied Sciences in Zittau/Görlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation and the development of CFD models for the description of particle transport phenomena in coolant flow. While the experiments are performed at the University Zittau/Görlitz, the theoretical work is concentrated at Forschungszentrum Dresden-Rossendorf.

The main topics of the project are

  • Primary particle constitution: Experiments are performed to blast blocks of insulation material by steam under the thermal hydraulic conditions to be expected during a LOCA incident (i.e. at pressures up to 11 MPa). The material obtained by this method is then used as raw material for further experiments.

fus_fig1

Fig. 1: Photography of sinking fibers (left side) and measured distribution of sinking velocities (right)

  • Transport behaviour of fibres in a  water flow: The transport behaviour of the steam-blasted material is investigated in a water column by optical high-speed video techniques. The sinking velocities of the fibres are then used to derive the drag coefficients and other physical properties of the modelled fibre phase, which is necessary for the implementation of an adequate CFD simulation. Further investigations were performed in a narrow channel with a racetrack type configuration with defined boundary conditions. Laser PIV measurements and high-speed video were used for the investigation of the water flow-field and the fibre concentration. Besides the drag acting on the particles, the turbulent dispersion force plays an important role in determining the momentum exchanged between the water and the fibrous phase.
  • Deposition and re-suspension of fibres: The deposition and re-suspension behaviour at low velocities was investigated by the same techniques and the narrow racetrack channel. Except that, in this case obstacles were inserted into the channel to change locally the flow regime. The experiments are designed to work with laser PIV measurement and high-speed video to investigate the fibre agglomeration in the obstacle region. CFD approaches consider the influence of the fibre material on the mixture viscosity and the dispersion coefficient on the transport of the solids.
  • Effect of strainers: A test rig was used to study the influence of the insulation material loading on the pressure difference observed in the region of the strainers. A CFD model was developed that uses the approach of a porous body. The calculated differential pressure considers compactness of the porous fibre layer. Correlations from the filter theory known in chemical engineering are adapted to the certain fibre material properties by experiments. This concept enables the simulation of a partially blocked strainer and its influence on the flow field.
  • Behaviour of a plunging jet in a large pool: By using high-speed video and laser (LDA and PIV) measurements, the progression of the momentum by the jet in the pool is investigated. Of special importance is the role that entrained gaseous bubbles play on disturbing the fluid and potentially influencing the fibre sedimentation and resuspension.
  • Containment sump scale multiphase experiments and modelling

fus_fig4

Fig. 2: Fibres in a tank influenced by a plunging jet. Gas bubbles are presented as streamlines, the location of the fibres is shown by an isosurface of the fibre volume fraction

 

Publications:

  • Krepper, E.; Weiß, F.-P.; Alt, S.; Kratzsch, A.; Renger, S.; Kästner, W. : Influence of air entrainment on the liquid flow field caused by a plunging jet and consequences for fibre deposition. Nuclear Engineering and Design 241(2011), 1047-1054
  • Krepper, E.; Cartland-Glover, G.; Grahn, A.; Weiß, F.-P.; Alt, S.; Kratzsch, A.; Renger, S.; Kästner, W.: CFD analyses of fibre transport and fibre deposition at plunging jet conditions. Kerntechnik 76(2011)1, 30-38
  • Alt, S.; Hampel, R.; Kästner, W.; Kratzsch, A.; Renger, S.; Seeliger, A.; Zacharias, F.; Cartland-Glover, G.; Grahn, A.; Hoffmann, W.; Krepper, E.; Kryk, H. : Generic experiments at the sump model “Zittauer Strömungswanne” (ZSW) for the behaviour of mineral wool in the sump and the reactor core. Kerntechnik 76(2011)1, 20-29
  • Grahn, A.; Krepper, E.; Weiß, F.-P.; Alt, S.; Kästner, W.; Kratzsch, A.; Hampel, R. : Implementation of a pressure drop model for the CFD simulation of clogged containment sump strainers. Journal of Engineering for Gas Turbines and Power - Transactions of the ASME 132(2010)
  • Krepper, E.; Grahn, A.; Cartland-Glover, G.; Weiss, F.-P.; Alt, S.; Kratzsch, A.; Renger, S.; Kästner, W. "CFD-Analyses on the behaviour of mineral wool in the reactor sump", Fachtagung der KTG-Fachgruppen, 07.-08.10.2010, Rossendorf, Deutschland, Aktuelle Themen der Reaktorsicherheitsforschung in Deutschland, 7.-8.10.2010 Rossendorf
  • Kratzsch, A.; Renger, S.; Kaestner, W.; Hampel, R.; Krepper, E. "Influence of an impinging jet on sedimented debris", 18th International Conference on Nuclear Engineering, ICONE18, 17.-21.05.2010, Xi'an, China
  • Krepper, E.; Weiss, F.-P.; Alt, S.; Kratzsch, A.; Renger, S.; Kästner, W. "Some nuclear reactor safety related aspects of plunging jets", 18th International Conference on Nuclear Engineering, ICONE18, 17.-21.05.2010, Xi'an, China
  • Krepper, E.; Cartland-Glover, G., Grahn, A., Weiß, F.-P.; Alt, S.; Hampel, R., Kästner, W., Seeliger, A. "CFD-modeling of insulation debris transport phenomena in water flow", Nuclear Engineering and Design 240 (2010) 2357–2364
  • Krepper, E.; Cartland-Glover, G.; Grahn, A. 2009. "CFD-modelling of insulation debris transport phenomena in water flow", Kerntechnik 74(2009)5-6, 255-264
  • Cartland Glover, G. M.; Grahn, A.; Krepper, E.; Weiss, F.-P.; Alt, S.; Hampel, R.; Kaestner, W.; Kratzsch, A.; Zacharias, F. 2009:"Hydrodynamic modeling of mineral wool fiber suspensions in a two-dimensional flow", The 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13), Kanazawa, Japan, September 27-October 2, 2009
  • Krepper, E.; Alt, S.; Renger, S., 2009: Influence of air entrainment on the liquid flow field caused by a plunging jet, Nuclear Energy for New Europe NENE-2009, 14.-17.09.2009, Bled, Slovenia
  • Krepper, E.; Cartland-Glover, G.; Grahn, A., 2009: "CFD Modellierung einer partikelbelasteten Kühlmittelströmung im Sumpf und in der Kondensationskammer", Wissenschaftlich-Technische Berichte / Forschungszentrum Dresden-Rossendorf; FZD-521, Aug. 2009
  • Cartland Glover, G.; Grahn, A.; Krepper, E.; Weiss, F.-P.; Alt, S.; Hampel, R.; Kaestner, W.; Kratzsch, A.; Zacharias, F. 2009:"Hydrodynamic modeling of mineral wool fiber suspensions in a two-dimensional flow", 17th International Conference on Nuclear Engineering, ICONE-17, 12.-16.07.2009, Brussels, Belgium
  • Grahn, A.; Krepper, E.; Weiß, F.-P.; Alt, S.; Kästner, W.; Kratzsch, A.; Hampel, R., 2009: "Implementation of a pressure drop model for the CFD simulation of clogged containment sump strainers", 17th International Conference on Nuclear Engineering, ICONE-17, 12.-16.07.2009, Brussels, Belgium
  • Krepper, E.; Cartland-Glover, G.; Grahn, A.; Weiss, F.-P.; Alt, S.; Hampel, R.; Kästner, W.; Seeliger, A. ,2009: CFD-modelling and experiments of insulation debris transport phenomena in water flow, Nuclear Technology 167(2009)1, 46-59
  • Krepper, E.; Cartland-Glover, G.; Grahn, A.; Weiss, F.-P.; Alt, S.; Hampel, R.; Kästner, W.; Seeliger, A., 2008, Experiments and CFD-modelling of insulation debris transport phenomena in water flow, Experiments and CFD Codes Application to Nuclear Reactor Safety, (XCFD4RS), 10.-12.09.2008, Grenoble, France
  • Krepper, E., Cartland-Glover, G., Grahn, A, Weiss, F.-P., Alt, S, Hampel, R. Kästner, W., Seeliger, A., 2008, Experimental investigation and CFD simulation of the behaviour of mineral wool in the reactor sump, 16th International Conference on Nuclear Engineering (ICONE16), May 11-15, 2008, Orlando, USA, paper ICONE16-48121
  • Krepper, E.; Cartland-Glover, G.; Grahn, A.; Weiss, F.-P.; Alt, S.; Hampel, R.; Kästner, W.; Seeliger, A., 2008. Numerical and experimental investigations for insulation particle transport phenomena in water flow, Annals of Nuclear Energy 35 (2008), 1564–1579
  • Weiss, F.-P.; Alt, S.; Cartland-Glover, G.; Grahn, A.; Hampel, R.; Kästner, W.; Krepper, E.; Seeliger, A., 2007. Investigation of the behaviour of mineral wool in the reactor sump, invited lecture at the "Quadripartite Meeting on Sump Screen Blockage", 17.-18.10.2007, Erlangen, Germany
  • Krepper, E.; Cartland-Glover, G.; Grahn, A.; Weiss, F.-P.; Alt, S.; Hampel, R.; Kästner, W.; Seeliger, A., 2007. CFD-modelling of insulation debris transport phenomena in water flow, The 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-12), 30.09.-04.10.2007, Pittsburgh, USA
  • Cartland-Glover, G.; Alt, S.; Kästner, W.; Krepper, E., 2007, Application of multiphase flow modeling techniques to the transport of submerged mineral wool fibers; 6th International Conference on Multiphase Flow, ICMF Leipzig Germany 2007
  • Krepper, E.; Cartland-Glover, G.; Grahn, A.; Weiß, F.-P.; Alt, S.; Hampel, R.; Kästner, W.; Seeliger, A., 2007, CFD-modelling of mineral wool in the containment sump; Jahrestagung Kerntechnik, 22.-24.05.2007 Karlsruhe, Germany
  • Cartland-Glover, G.; Alt, S.; Kästner, W.; Krepper, E., 2007, Numerical investigations of the transport of submerged insulation particle; Jahrestagung Kerntechnik, 22.-24.05.2007 Karlsruhe, Germany
  • Alt, S.; Hampel, R.; Kästner, W.; Grahn, A.; Krepper, E., 2006, Experimental investigations for head loss build up at clogged strainers after LOCA; Jahrestagung Kerntechnik, 16.-18.5.2006, Aachen, Germany
  • Grahn, A.; Krepper, E.; Alt, S.; Kästner, W. 2006, 1D-modelling of differential pressure buildup at clogged containment sump strainers after LOCA, Jahrestagung Kerntechnik, 16.-18.5.2006, Aachen, Germany
  • Krepper, E.; Grahn, A., 2006, Untersuchung des Verhaltens von freigesetztem Isolationsmaterial in einer Kühlmittelströmung (Kühlmittelströmung mit Feststoffpartikeln) – Modellentwicklung; Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-458 2006
  • Krepper, E.; Grahn, A.; Kästner, W., 2006, CFD-Simulation von Mineralwollpartikeln in der Sumpfströmung, Aktuelle Themen der Reaktorsicherheitsforschung in Deutschland, KTG-Fachgruppen "Sicherheit kerntechnischer Anlagen" und "Betrieb von kerntechnischen Anlagen", 03.-04.04.2006, Dresden, Germany
  • Grahn, A.; Krepper, E.; Alt, S.; Kästner, W., 2006, Modelling of differential pressure buildup during flow through beds of fibrous materials, Chemical Engineering & Technology 29(2006)8, 997-1000
  • Krepper, E.; Alt, S.; Grahn, A., Seeliger, A., 2005, Experimental and analytical investigations for debris transport phenomena in multidimensional water flow, The 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), 02.-06.10.2005, Avignon, Frankreich
  • Krepper, E.; Grahn, A.; Alt, S.; Kästner, W.; Kratzsch, A.; Seeliger, A., 2005, Numerical investigations for insulation particle transport phenomena in water flow; International Conference "Nuclear Energy for New Europe", 05.-08.09.2005, Bled, Slovenia
  • Alt, S.; Hampel, R.; Kästner, W.; Lischke, W.; Seeliger, A.; Krepper, E.; Grahn, A., 2005, Untersuchungen zum Verhalten von freigesetztem Isolationsmaterial in ruhender und horizontaler Kühlmittelströmung, Jahrestagung Kerntechnik, 10.-12.05.2005, Nürnberg
  • Hampel, R.; Kästner, W.; Alt, S.; Seeliger, A.; Krepper, E.; Grahn, A., 2004, Experimental and Numerical Investigations for Fragmentation and Insulation Particle Transport Phenomena in Water Flow, 5th International Conference on Multiphase Flow, ICMF'04, Yokohama, Japan, May 30–June 4, 2004, Paper No. 555
  • Krepper, E.; Grahn, A., 2004, Numerical investigations of insulation debris transport phenomena in water flow, OECD Workshop on Debris Impact on Emergency Coolant Recirculation, Albuquerque, NM (USA), 25-27 February 2004

Acknowledgements:

The work is carried out as a part of current research projects funded by the German Federal Ministry of Economics and Technology, project numbers 1501270 and 150 1307.

Cooperations:

University of Applied Sciences Zittau/Görlitz

ANSYS/CFX


Contact

Dr. Eckhard Krepper
Computational Fluid Dynamics
e.krepperAthzdr.de
Phone: +49 351 260 - 2067
Fax: +49 351 260 - 12067

Dr. Alexander Grahn
Reactor Safety
a.grahnAthzdr.de
Phone: +49 351 260 - 2331
Fax: +49 351 260 - 12331