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25-27/10/2005, 1
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe
Calculational Support for the QUENCH-10 and QUENCH-11 Experiments
J Birchley, T Haste, B Jaeckel
Calculational Support for QUENCH-10 and -11 Experiments, 2
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Introduction
• Calculational support has continued at PSI for the QUENCH test series– post-test calculations for QUENCH-10– pre-test calculations for QUENCH-11
• This support has been provided using the two main calculational routes used at PSI for core degradation analysis– MELCOR1.8.5, integrated engineering-level approach, used extensively for
plant studies– SCDAP-based codes (SCDAP/RELAP5/MOD3.2, SCDAPSIM/MOD3.4), for
more detailed analysis of specific points
• General aims are to help with test definition, and to improve understanding of the results
Calculational Support for QUENCH-10 and -11 Experiments, 3
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Post-test calculations for QUENCH-10
• Pre-test and post-test calculations were reported at the 10th QUENCH Workshop– MELCOR1.8.5 RD– SCDAP/RELAP5/MOD3.2(hx) with improvements by FZK/IRS including
modifications to the heater rod model
• SCDAPSIM/MOD3.4 is being increasingly used at PSI for supporting plant sequence calculations– Faster and more stable performance in many circumstances
• Post-test calculations have been repeated with SCDAPSIM to compare its performance with that of SCDAP/RELAP5– Preparatory step to developing an air ingress model
• A pre-requisite to calculating the air-oxidation is to replicate the initial thermal and oxidised state of the bundle; the current work benchmarks the models against the pre-oxidation phase
Calculational Support for QUENCH-10 and -11 Experiments, 4
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
QW-10 results with SCDAP/RELAP5/MOD3.2 PSI version – centre rod
• Temporary modifications were made to S/R5 to model the air oxidation
Calculational Support for QUENCH-10 and -11 Experiments, 5
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
QW-10 results with SCDAP/RELAP5/MOD3.2 PSI version – shroud
• Air oxidation modelling to be added later to SCDAPSIM
Calculational Support for QUENCH-10 and -11 Experiments, 6
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
QUENCH-10 input model using SCDAPSIM
• Same basic model as used for SCDAP/RELAP5– Derived from one supplied by FZK
• Noding and components– Central unheated rod, inner heated rods, outer heated rods, corner rods,
shroud, Ar and water cooling systems– 16 axial nodes to represent the test section– 10 x 0.1 m nodes for the tungsten heated section
• Comparative calculations performed amongst SCDAPSIM, S/R5 PSI version and S/R5 IRS versions with the same input as far as possible– Some changes needed to take into account the different models and options
available– External resistance of the heater rods used as a tuning parameter, aiming to
match the total H2 production of 47.3g in the steam pre-oxidation period
Calculational Support for QUENCH-10 and -11 Experiments, 7
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Differences between SCDAPSIM and S/R5/3.2hx (irs/psi) models
SCDAP/RELAP5/MOD3.2hx(irs/psi) SCDAPSIM/MOD3.4(bi5)
Composition of shroud constant axially Composition of shroud may be axially dependent
Boundary condition temperatures of end heater rod nodes set for the ends of the nodes
Boundary condition temperatures of end heater rod nodes set for the node midpoints
Physical properties of user-specified materials (used for shroud): specific heat, density, thermal conductivity, emissivity, thermal expansion
Physical properties of user-specified materials: specific heat, density, thermal conductivity only
FZK/IRS changes to RELAP5 models ISS changes to thermal hydraulic models, includes smoothing between flow regimes to improve stability and speed
Standard timestep control options (semi- and nearly-implicit)
Additional options that can give faster running (need to be used with care, watch mass error!)
Calculational Support for QUENCH-10 and -11 Experiments, 8
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Differences between SCDAPSIM and S/R5/3.2hx (irs/psi) input data
• Shroud model– Constant composition with S/R5, but can treat different cooling jackets– Varying composition with SSim to treat absence of insulator above W heated section
• Heater rod boundary condition– S/R5, constant temperature at each end, 300K– SSim, constant temperature of 400K at bottom (300K leads to condensation), tied to
top RELAP volume gas temperature at the top via a control function
• Shroud physical properties– Emissivity and thermal expansion of shroud materials not input for SSim, tried some
mild tuning of the conductivity but this is not sufficient to improve the results
• New option ’39’ for taking bigger timesteps in SSim tried, but no advantage in this case (but there is in some plant transients)
• Cu tried for end nodes in SSim rather than Mo, more realistic but after retuning the external resistance there is no strong difference in the results
Calculational Support for QUENCH-10 and -11 Experiments, 9
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Centre rod temperature histories for SCDAPSIM
Calculational Support for QUENCH-10 and -11 Experiments, 10
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Comparison of hydrogen production in the pre-oxidation phase
Calculational Support for QUENCH-10 and -11 Experiments, 11
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Axial temperature profile in bundle at end of high temperature oxidation phase
0
500
1000
1500
2000
-500 -300 -100 100 300 500 700 900 1100 1300 1500
Axial position, mm
Tem
per
atu
re,
K
QUENCH-10 Rod data, 9319s
comp2 - ssim ss5ptr Cu 4.0mohm
comp2 - ssim ss5qtr Mo 3.4mohm
comp2 - sr5irs ss4tr Mo 5.0mohm
comp2 - sr5psi ss5tr Mo 3.6mohm
Calculational Support for QUENCH-10 and -11 Experiments, 12
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Axial temperature profile in shroud at end of high temperature oxidation phase
0
500
1000
1500
2000
-500 -300 -100 100 300 500 700 900 1100 1300 1500
Axial position, mm
Tem
per
atu
re, K
QUENCH-10 Shroud liner data, 9319s
comp5 - ssim ss5ptr Cu 4.0mohm
comp5 - ssim ss5qtr Mo 3.2mohm
comp5 - sr5irs ss4tr Mo 5.0mohm
comp5 - sr5psi ss5tr Mo 3.6mohm
Calculational Support for QUENCH-10 and -11 Experiments, 13
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Conclusions from QUENCH-10 calculations
• SCDAP/RELAP5/MOD3.2hx (irs/psi) gives temperature histories peaking at the same axial location as observed– Adequate for starting air phase calculation– However poorer agreement in the shroud above the heated section
• SCDAPSIM gives peak one node (10cm) too low, with temperatures up to 200K too high in the mid region– Not adequate to start an air phase calculation, possibility of excursion starting in the wrong place– However improved agreement in the shroud region above the heated section, better shroud model
• Need to modify SCDAPSIM with features of SCDAP/RELAP5/MOD3.2hx (irs/psi) to improve calculation of QUENCH facility– Heater rod model including boundary conditions, additional user-defined material properties, there may be
others to be considered– Axially-dependent shroud properties and improved numerical performance are advantages for
SCDAPSIM– GUI interface for SCDAPSIM improves the usability (control of run, inspection of results on-line)
• Investigation into improving SCDAPSIM in this way in progress– No direct improvement for plant studies, but will aid assessment against QUENCH data, and is needed for
validation of a prospective air ingress model against QUENCH-10
Calculational Support for QUENCH-10 and -11 Experiments, 14
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Preliminary calculations for QUENCH-11
• SCDAPSIM/MOD3.4/bi5– input based on deck used by ISS for ISP-45 submission– modifications for initial filling, additional heating and water supply– bundle and additional power history, injection rates as used in FZK planning
calculations
• MELCOR 1.8.5 RD– input based on deck used by PSI for analysis of QUENCH-10– modifications analogous to SCDAPSIM
• Final definition of QUENCH-11 protocol is pending outcome of vorversuch
• Models set up to accommodate follow-on QUENCH-11– demonstrated in conceptual calculations (not presented at QWS 11)
Calculational Support for QUENCH-10 and -11 Experiments, 15
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction SCDAPSIM: Heat balance
Calculational Support for QUENCH-10 and -11 Experiments, 16
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction MELCOR: Heat balance
Calculational Support for QUENCH-10 and -11 Experiments, 17
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction SCDAPSIM and MELCOR: Liquid level
Calculational Support for QUENCH-10 and -11 Experiments, 18
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction MELCOR: Maximum cladding temperature
Calculational Support for QUENCH-10 and -11 Experiments, 19
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction SCDAPSIM: Cladding temperatures
Calculational Support for QUENCH-10 and -11 Experiments, 20
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction MELCOR: Cladding temperatures
Calculational Support for QUENCH-10 and -11 Experiments, 21
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction SCDAPSIM and MELCOR: Hydrogen mass
Calculational Support for QUENCH-10 and -11 Experiments, 22
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Vorversuch prediction MELCOR: Oxide thickness
Calculational Support for QUENCH-10 and -11 Experiments, 23
Laboratory for Thermal HydraulicsNuclear Energy and Safety
11th QUENCH Workshop, FZ Karlsruhe ,October 2005
Summary of QUENCH-11 support: Status and plans
• Prediction of vorversuch demonstrated with SCDAPSIM and MELCOR
• Definitive calculation of vorversuch to be performed as precursor to QUENCH-11– adjustment of input to reproduce observed transient
• Plan to perform pre-test (?) and post-test calculation of QUENCH-11
• SCDAPSIM appears better suited than MELCOR to boildown simulation
• Non-negligible cladding oxidation during vorversuch