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ERMSAR 2012, Cologne March 21 – 23, 2012
Pretest Calculations of QUENCH-DEBRIS-0 Test Using SOCRAT/V3 Code
VASILIEV A.D.
NUCLEAR SAFETY INSTITUTE OF RUSSIAN ACADEMY OF SCIENCES (IBRAE),
B.TULSKAYA 52, 115191 MOSCOW, RUSSIA
ERMSAR 2012, Cologne March 21 – 23, 2012
Content of Presentation
1. Purpose
2. QDEBRIS-0 Experiment Features
3. SOCRAT – Computer Modelling Code
4. SOCRAT Results of Modelling
5. Conclusions
ERMSAR 2012, Cologne March 21 – 23, 2012
Purpose
The QUENCH-DEBRIS-0 test is planned at QUENCH facility, KIT, Karlsruhe, Germany. The objective of this bundle test is the investigation of thermo-hydraulic, thermo-mechanical and physico-chemical phenomena under severe accident conditions with debris and melt pool formation.
The lessons learned from severe nuclear accidents at Three Mile Island, Chernobyl and Fukushima showed the very high importance of accident control measures to prevent the development of design basis accident to beyond design basis accident and to mitigate the consequences of beyond design basis accident.
The deep understanding of hydraulic, mechanical and chemical processes taking place under accident conditions is necessary, in particular, during late phase with debris formation.
ERMSAR 2012, Cologne March 21 – 23, 2012
Hafnia
QUENCH-DEBRIS-0 Features
Hafnium will be used in QDEBRIS tests
ERMSAR 2012, Cologne March 21 – 23, 2012
Hafnium-containing rocket nozzle of the Apollo Lunar Module
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0 Features
Hafnium-containing periphery rods, corner rods and shroud of QUENCH-DEBRIS facility
ERMSAR 2012, Cologne March 21 – 23, 2012
SOCRAT Computer Modelling Code
SOCRAT/V3
SOCRAT/V2
SOCRAT/V1
ERMSAR 2012, Cologne March 21 – 23, 2012
SOCRAT Nodalization Scheme for QUENCH-DEBRIS
ERMSAR 2012, Cologne March 21 – 23, 2012
SOCRAT: Debris Behaviour Module
Thermal Problem of SOCRAT Code
DEBRIS THERMAL HYDRAULIC MODULE
Debris solid and fluid oxidation
Calculation of thermo-physical
properties of debris solid/liquid phases
System solution (,s,,,,p) for new timestep
Calculation of debris materials relocation inside
debris and between debris and non-debris meshes
Geometry (topology) of debris from
formation criteria or input data
Matrix coefficients for conservation
equations
ERMSAR 2012, Cologne March 21 – 23, 2012
SOCRAT: Debris Behaviour Module Equations
1/ 2
ff ff f f f Ef f f f f f f
u u Cu p g u u u u
s t s s s K K
time convection pressure gravity Brinkmann Darcy Forchheimer
d diameter of particles3
22180(1 )
K d
permeability
2 3
2 216 (1 )h
K K fs
dK
k k A
2.5Kk
4
(1 )hfs
dA
hydraulic diameter EC Ergun constant
ERMSAR 2012, Cologne March 21 – 23, 2012
Energy Equations
ff f
f f f f d f f fus
s H pH u T H m s
t t
(1 )fs f f
sf sf s f nuc chh A T T q q fH sH Specific enthalpies
(1 )(1 ) (1 )
fs ss s s ss s s fus sf sf s f nuc ch
H pT H m h A T T q q
t t
fnucqfchq
d
internal heat generation rate due to fission products decay
internal heat generation rate due to chemical reactions
effective thermal conductivity due to hydrodynamic dispersion
ff eff
s f
ss eff
s f
effective solid thermal conductivity taking into account radiative heat transfer
effective solid thermal conductivity taking into account radiative heat transfer
ERMSAR 2012, Cologne March 21 – 23, 2012
Radiative Heat Transfer Modeling,g eff g rad effective conductivity of gas
34rad s BCa d T effective radiative conductivity
sa emissivity
C constant of the order of unity
B Stefan-Bolzman constant
, ,,
1
(1 )eff g eff g eff
g eff
sf
0.044
1.6
,
0.3 sf
g eff
1
g
sf volume-averaging conductivity of solid and liquid
ERMSAR 2012, Cologne March 21 – 23, 2012 Time, s
Temperature, K
1500
500
2500
Preliminary heat-up
Preoxidation
Finalheat-up
Cool-down
fast cool-down, water flood
slow cool-down, no water flood
ERMSAR 2012, Cologne March 21 – 23, 2012
Estimation of Melt Velocity Relocating Downward
ff
f f
K g Kgu
92.75 10K 6 21.0 10 /f m s
22.75 10 /fu m s
1 5 /fu mm s
Kozeny constant
Account of relative permeability
ERMSAR 2012, Cologne March 21 – 23, 2012
Basic Thermo-Physical Corium Parameters
3 35.4 10 0.2 10 (2 1)
5 58.8 10 0.2 10 (2 1)
7.5 5 (2 1)
0.57
2 2
2 2
/
/ /ZrO ZrO
ZrO ZrO Zr Zr
M m
M m M m
Pa·s, dynamic viscosity
K-1, volumetric expansion
W/(mK), thermal conductivity
N/m, surface tension
Zr oxidation extent
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0:Calculated Temperature
Behaviour
Maximum temperature is about 2500K
The first heat-up phase and preoxidation phase are similar to classical QUENCH-06 test!
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0: Proposed Total Electric Power
0 1000 2000 3000 4000 5000T im e, s
0
10000
20000
30000
40000
50000
Pow
er, W
Q U E N C H -0 2
Q U E N C H -03
Q U E N C H -0 9
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0: Chemical Reactions
Zr + 2H2O = ZrO2 + 2H2 + Q1
Zr + O2 = ZrO2 + Q2
yes
no
yesHf + 2H2O = HfO2 + 2H2 + Q3
Q1 =6.45 106 J/kg Zr
Q2 =12.0 106 J/kg Zr
Q3 =2.6 106 J/kg Hf
ERMSAR 2012, Cologne March 21 – 23, 2012
E-110 (Zr1%Nb) Oxidation Rate
KtW 2 weight gain, mg/cm2; K - rate constant, mg2/(cm4s)
RT
QAK exp Q - activation energy, J/mole; R – gas constant, J/(moleK); T – temperature,
K
tRT
QAKtW
2exp2/1
K=
T
23040exp1059.1 6
T
20800exp10825.9 5
T
20820exp10464.8 5
550C<T<1200C
1300C<T<1500C
1500C<T<1600C
Bibilashvili Yu.K., Sokolov N.B., Andreyeva-Andrievskaya L.N., Salatov A.V. High-Temperature Interaction of Fuel Rod Cladding Material (Zr1%Nb Alloy) with Oxygen-Containing Mediums. IAEA-TECDOC-921, Dimitrovgrad, 1995, p.117-128.
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0:Hafnium Oxidation Rate
K = 0.76 kg/(m2s1/2)
Ea = 78423 J/mole
Steinbrueck et. al. High-Temperature oxidation and quench behaviour of Zircaloy-4 and E110 cladding alloys. Progress in Nuclear Energy, 52(2010), pp. 19-36.
Hafnium oxidation rate is several times lower!
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0: Calculated Heat Balances in Core
0 2000 4000 6000 8000 10000Time, s
0
10000
20000
30000
Pow
er, W
Q electric core
Q coolant
Q shroud
Q chemical
1
2
34
1 – total electric power
2 – heat transferred by gas
3 – heat to shroud
4 – chemical power
All rods and shroud made of Zry!
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0: Calculated Electric Current and H2 Rate
Hydrogen generation rate
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0: Calculated Hydrogen Production
0 2000 4000 6000 8000 10000T im e, s
0
0.02
0.04
0.06
0.08
0.1
Hyd
roge
n p
rod
uct
ion
, kg
1
2
1 - total H2 release
2 - H2 release in debris
All rods and shroud made of Zry!
ERMSAR 2012, Cologne March 21 – 23, 2012
QUENCH-DEBRIS-0: Diminishing Steam Mass Flow Rate Leads to More Wide Axial Temperature Profile
Calculated Axial Distribution of Zirconia Layer Thickness
Discover new fundamental nature laws with QUENCH-DEBRIS!
This ambitious program will help in more realistic desription of debris-
related phenomena under NPP accident conditions!
LABORATORY
A fast heat-up rate scenario after pre-oxidation is proposed to get massive high temperature porous debris and pool zone during QDEBRIS-0 test.
Application of Hafnium instead of Zircaloy leads to more manoeuvrable and flexible experiment control.
Conclusions
SOCRAT code was used to estimate basic parameters of the test.
Such important issues as debris oxidation and relocation phenomena, debris hydraulics as well as the coolability of massive debris bed can be investigated.
-5 s-4 s-3 s-2 s-1 s 0 s