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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

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


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

Experimental Data & Facilities

IAEA 4th RCM on Natural Circulation

IAEA – HQ, Vienna, Austria

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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


Phenomenon 9 liquid temperature stratification

Experimental Data & Facilities (cont)

  • TPFL at Idaho State University (2006), cont

IAEA 4th RCM on Natural Circulation

IAEA – HQ, Vienna, Austria

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

Analytical Models

IAEA 4th RCM on Natural Circulation

IAEA – HQ, Vienna, Austria

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

Computational Models

IAEA 4th RCM on Natural Circulation

IAEA – HQ, Vienna, Austria

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

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

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10 – 13 Sept 2007


Phenomenon 9 liquid temperature stratification

Path Forward

IAEA 4th RCM on Natural Circulation

IAEA – HQ, Vienna, Austria

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Phenomenon 9 liquid temperature stratification

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

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IAEA – HQ, Vienna, Austria

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