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Phenomenon 9 Liquid Temperature Stratification

Phenomenon 9 Liquid Temperature Stratification. Involved Institutions FZR, ISU, OSU, and UPV presentation by B. Williams, ISU. IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria. 10 – 13 Sept 2007. Presentation Outline. Review of phenomenon definition

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Phenomenon 9 Liquid Temperature Stratification

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  1. Phenomenon 9 Liquid Temperature Stratification Involved Institutions FZR, ISU, OSU, and UPV presentation by B. Williams, ISU IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 10 – 13 Sept 2007

  2. Presentation Outline • Review of phenomenon definition • Results of research into: • Experimental Data & Facilities • Analytical Models • Computational Models • Path forward IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 2 10 – 13 Sept 2007

  3. Definition of Phenomenon 9 • Large temperatures in the working fluid as a result of • Local cooling caused b emergency core coolant (ECC) injection • Local heating caused by steam condensation • Heat exchanger heat transfer • Of interest in natural circulation due to limited amount of fluid mixing • that may occur • This phenomenon is restricted to • Lower plenum of vessel • Downcomer of vessel • Horizontal or vertical piping IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 3 10 – 13 Sept 2007

  4. Experimental Data & Facilities IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 4 10 – 13 Sept 2007

  5. Experimental Data & Facilities • Reyes at Oregon State University (2005) • APEX test facility • For low ECC flow rates, cold injected fluid stratifies in the loops • and form cold plumes in the downcomer • Could lead to Pressurized • Thermal Shock (PTS) in a • pre-existing flaw in the • vessel wall or welds • Provided support for postulated • mechanisms leading to • thermal stratification Reyes, J. N., 2005, “Flow Stagnation and Thermal Stratification in Single and Two-Phase Natural Circulation Loops”, in IAEA Tecdoc 1474: Natural Circulation in Water Cooled Nuclear Power Plants, Annex 15 (433-459) IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 5 10 – 13 Sept 2007

  6. Experimental Data & Facilities (cont) • Imatran Voima Oy (IVO) Transparent Test Facility in Helsinki, Finland (1986) • 2/5 scale multi-loop transparent test facility • Flow visualization examining • downcomer plume behavior • HPI fluid is indicated by • the dye. • Loop flow rate 10 times • greater than that of HPI • fluid Tuomisto, H. and P. Mustonen, 1986, “Thermal Mixing Tests in a Semiannular Downcomer with Interacting Flows from Cold Legs”, U. S. Nuclear Regulatory Commission, NUREG/IA-0004, October IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 6 10 – 13 Sept 2007

  7. Experimental Data & Facilities (cont) • Cheng, et al. at Purdue University (2006) • U.S. NRC supported testing of thermal stratification and pool • mixing inside the suppression pool during reactor blowdown • Condensation of steam with noncondensables inside suppression • pool is important in determining the safe containment pressure • Purdue University Multi-Dimensional Integral Test Assembly • (PUMA) • Test boundary conditions obtained from RELAP5 during a LOCA • Testing ranges • Drywell pressures of 200 kPa, 230 kPa, and 260 kPa • Steam flow rates of 70 g/s and 120 g/s • Suppression pool initial temperatures of 40 °C, 50 °C, and 60 °C • Air mass concentrations of 0, 0.5%, 2.5%, and 5% Cheng, Ling, et al., 2006, “Suppression Pool Mixing and Condensation Tests in PUMA Facility”, in Proceeding of ICONE 14, International Conference on Nuclear Engineering, July 17-20, Miami, FL, USA IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 7 10 – 13 Sept 2007

  8. Experimental Data & Facilities (cont) • Cheng, et al. at Purdue University (2006), cont • Concluded that the degree of thermal stratification in the • suppression pool is • Strongly affected by the noncondensable gas injection flow rate • Affected by the vent opening depth, the pool pressure, and the • steam flow rate • Slightly affected by the pool water initial temperature IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 8 10 – 13 Sept 2007

  9. Experimental Data & Facilities (cont) • Liou at the University of Idaho (2006) • Instrumented air-water-brine flow loop Williams, et al., 2006, Final Report for DOE NEER-Funded Project “Providing the Basis for Innovative Improvements in Advanced LWR Passive Safety System Design: An Educational R&D Project”, Award No DE-FG07-03ID14500, report for the period July 16, 2003 to July 15, 2006 IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 9 10 – 13 Sept 2007

  10. Experimental Data & Facilities (cont) • Liou at the University of Idaho (2006), cont • Observed stationary fresh water (dyed) wedge over clear brine flow • Correlated wedge length to upstream densimetric Froude number IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 10 10 – 13 Sept 2007

  11. Experimental Data & Facilities (cont) • Schultz, Kondo, and Anoda at the JAERI TPTF (2001) • Two-Phase Fluid Test Facility (TPFT) at JAERI’s Tokai Research • Center • Investigation to understand condensation-induced water hammer • (CIWH) data recorded in a series of experiments • 10-m long 0.183-m diameter test section at a pressure of 0.61 MPa with • 137 K of subcooling • For horizontally-stratified flow, CIWH events divided into discrete • stages: • Formation of a wave bridge and slug • Rapid condensation of enclosed steam bubble • Movement of slug into low pressure region • Impact of slug on structures or other bodies • Propagation of resulting pressure pulse throughout the system • Restoration of system to pre-CIWH conditions Schultz, Richard R., Masaya Kondo, and Yoshinari Anoda, 2001, “Baseline Study to Model a Typical Condensation-Induced Water Hammer Event Measured at the Two-Phase Flow Test Facility (TPFT) in Japan”, in Proceedings of the Pressure Vessel & Piping Conference, July 22-26, 2001, Atlanta, GA, USA IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 11 10 – 13 Sept 2007

  12. Experimental Data & Facilities (cont) • TPFL at Idaho State University (2006) • Steam/water loop operating slightly greater than atmospheric, • saturated water temperatures, subcooled water flow rates < 10 gpm • Determine precursor events leading up to the formation of CIWH in • the horizontal leg of ECC system piping • Determine impact of a saturated water layer separating steam from • subcooled liquid (stratified flow) • Use a saturated wedge to mitigate CIWH • In addition to temperature, pressure, and flow measurements, visual • methods used through the inclusion of a transparent (glass) • horizontal test section • Development of the experiment provides the basis for 1 PhD • student’s dissertation • Experiment is currently on-going Williams, et al., 2006, Final Report for DOE NEER-Funded Project “Providing the Basis for Innovative Improvements in Advanced LWR Passive Safety System Design: An Educational R&D Project”, Award No DE-FG07-03ID14500, report for the period July 16, 2003 to July 15, 2006 IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 12 10 – 13 Sept 2007

  13. Experimental Data & Facilities (cont) • TPFL at Idaho State University (2006), cont IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 13 10 – 13 Sept 2007

  14. Analytical Models IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 14 10 – 13 Sept 2007

  15. Analytical Models • Reyes at Oregon State University (2005) • Analytical modeling in support of APEX PTS Testing • Quantified the onset of thermal stratification in horizontal cold leg • as a function of a modified Froude number • From basic principles including applying three key assumptions • from forced plume behavior analysis • Taylor’s entrainment assumption • Mean inflow velocity across the edge of the plume is proportional to the • local mean downward velocity of the plume • Similarity of velocity and buoyancy profiles • Gaussian profile for mean vertical velocity and mean buoyancy Reyes, J. N., 2005, “Flow Stagnation and Thermal Stratification in Single and Two-Phase Natural Circulation Loops”, in IAEA Tecdoc 1474: Natural Circulation in Water Cooled Nuclear Power Plants, Annex 15 (433-459) IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 15 10 – 13 Sept 2007

  16. Analytical Models (cont) • Reyes at Oregon State University (2005), cont • Developed for (1) forced axisymmetric plumes and (2) planer plumes: • Governing differential equations • Initial conditions • Boundary conditions • Dimensionless balance equations • Plume decay correlations (forced axisymmetric plumes) • Plume velocity and heat transfer (planer plumes) IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 16 10 – 13 Sept 2007

  17. Analytical Models (cont) • Zare Shahneh at the Atomic Energy Organization of Iran (2002) • Developed model of mass flow rate through vertical fuel plate • channels • Pool-type Tehran Research Reactor (TRR) • For off-pump conditions in which natural circulation is heat removal • mechanism from fuel plates • Model developed using conservation equations • Results predict a non-linear decrease in mass flow rate due to • thermal stratification Zare Shahneh, Abolghasem, 2002, “Effect of Thermal Stratification of Coolant in a Vertical Heated Channel”, in Proceedings of ICONE 10, International Conference on Nuclear Engineering, April 14-18, Arlington, VA, USA IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 17 10 – 13 Sept 2007

  18. Analytical Models (cont) • Liou at the University of Idaho (2006) • Analytical efforts in support of the instrumented air-water-brine • flow loop experiment described previously • Used basic principles to predict • length of observed stationary • wedge of saturated water • Compared analytic model • results to data Williams, et al., 2006, Final Report for DOE NEER-Funded Project “Providing the Basis for Innovative Improvements in Advanced LWR Passive Safety System Design: An Educational R&D Project”, Award No DE-FG07-03ID14500, report for the period July 16, 2003 to July 15, 2006 IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 18 10 – 13 Sept 2007

  19. Analytical Models (cont) • Schultz at the INL (2006) • Expanded work previously described with Kondo and Anoda • Constructing a mechanistic model that describes • Wave amplitude for subcooled flow • Moving in a horizontal pipe • Covered by a saturated liquid wedge (hence stratified flow) • Steam flowing above the free surface • Model will result in a transition line from Stratified Wavy to • Intermittent for a generalized flow regime map • Used wave analysis techniques from Crowley, Wallis, and Barry • Successfully related to work of Taitel & Dukler • Appears to have greater applicability and more potential than the • approaches base on Kelvin-Helmholtz instability analysis • Comparison of model results to data generated at the ISU TPFL Schultz, Richard R., 2006, “Using Stratified Flow to Mitigate Condensation-Induced Water Hammer”, Ph.D. thesis proposal, Idaho State University, Pocatello, ID, USA IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 19 10 – 13 Sept 2007

  20. Computational Models IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 20 10 – 13 Sept 2007

  21. Computational Models • Wachs at ANLW and Reyes & Davis at OSU (1998) • Computational efforts in support of APEX testing mentioned • previously • Intended to predict the onset and severity of thermal stratification in the • cold legs • CFD code used was CFX 4.1 • Model simulated thermal hydraulic conditions within • Steam generator lower plenum • Cold legs • Downcomer • Model setup to simulate three system conditions • Full natural circulation • Reduced natural circulation • Loop stagnation Wachs, D. M, J. N. Reyes, Jr., and L. R. Davis, 1998, “A Study of Thermal Stratification in the Cold Legs During the Subcooled Blowdown Phase of a Loss of Coolant Accident in the OSU APEX Thermal Hydraulic Testing Facility”, in Proceedings of the American Nuclear Society Winter Meeting, November 15-19, Washington, D.C., USA IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 21 10 – 13 Sept 2007

  22. Computational Models (cont) • Wachs at ANLW and Reyes & Davis at OSU (1998), cont • Model was able to predict thermal stratification • Model also suggested that the cold leg conditions may be non- • symmetric • Criterion for predicting the onset of thermal stratification was • established based on • Cold leg Froude number • Ratio of the natural circulation and the PRHR injection flow IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 22 10 – 13 Sept 2007

  23. Computational Models (cont) • Muñoz-Cobo, Escrivá, and de la Rosa at Universidad Politécnica de • Valencia • Study of liquid temperature stratification in piping • Used both commercially available CFD code CFX 5.4.1 as well as • UPV-developed code TUBE-3D • CFX code results compared with measured data from the hot legs • of Vandellos II • Range of temperatures is very similar • Values differ slightly due to thermocouple technique in which an • average for a radial region was measured • TUBE-3D code • Solved in 3D mass, energy, and momentum equations in conjunction • with the k-ε turbulence model • Showed high accuracy in the simulation of stratification in sections of • straight pipe Muñoz-Cobo, J. L, A. Escrivá, and J. C. de la Rosa, “Liquid Temperature Stratification in Piping of Nuclear Power Plants”, Universidad Politécnica de Valencia, Spain IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 23 10 – 13 Sept 2007

  24. Path Forward IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 24 10 – 13 Sept 2007

  25. Path Forward • Continue with students performing literature search • Complete draft write-up by deadline (Oct ?) • Really, I promise… • Provide to FZD, OSU, and UPV for comments, edits, and additions • Provide to CRP members for review & comments IAEA 4th RCM on Natural Circulation IAEA – HQ, Vienna, Austria 25 10 – 13 Sept 2007

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