The RAPTA-5.2: Code for Modeling of VVER Type Fuel Rod - IAEA

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
The RAPTA-5.2:
Code for Modeling of VVER Type Fuel Rod Behavior
under Design Basis Accidents Conditions
JSC “VNIINM”
JSC “TVEL”
Fedotov P.V., Goncharov A.A., Kumachev A.V., Nechaeva O.A., Novikov V.V.,
Salatov A.V., Pimenov Yu.V., Dolgov Yu.N.

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
RAPTA-5.2 simulates the following processes:
• Heat distribution from sources in the fuel to the
clad outer surface;
• Thermoelastic deformation of fuel, additional
swelling and gas release depending on
temperature rise;
• Thermoelastic-plastic deformation of the cladding
under external coolant pressure, inner gas
pressure and mechanical interaction with fuel
pellet (PCMI);
• Cladding oxidation taking heat release into
account;
• Inner gas pressure;
• Cladding failure during ballooning.

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
High temperature oxidation
E110 sponge based alloy irradiated at MIR reactor up to burnup 38 MWt*d/kgU
After irradiation After oxidation at 1100 °C during 2100 s
E110 alloy irradiated at Balakovo NPP up to burnup 65 MWt*d/kgU
After irradiation After oxidation at 1100 °C during 3600 s

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
Temperature, C
1200
1000
800
600
400
200
0 400 800 1200
Time, s
Typical experiment scenario
High temperature oxidation
RAPTA-5.2
30
20
10
0
calculation = experiment
0 10 20 30
Experiment
Specific weight gain

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
Burst tests
E110 alloy irradiated at Novovoronezh NPP up to burnup 48 MWd/kgU
Test procedure:
• sample heat up to the test temperature from 800 to 1200 °С,
• isothermal exposure,
• loading by inner pressure at rate 0.01MPa/s and registration of the pressure at burst
RAPTA-5.2
6
5
4
3
2
1
0
эксперимент=расчет
0 2 4 6
Experiment
Pressure at burst

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
Temperature, C
Temperature, C
1200
1000
800
600
400
200
1200
1000
0
4500 4600 4700 4800 4900 5000
Time, s
Temperature of cladding external surface
800
600
400
200
0
5400 5500 5600 5700 5800 5900
Time,s
Temperature of cladding external surface
Integral LOCA tests
PARAMETR – FRA №1 (VVER type)
Pressure, MPa
PARAMETR – FRA №2 (VVER type)
Pressure, MPa
4
3
2
1
0
4500 4600 4700 4800 4900 5000
Time, s
4
3
2
1
Internal pressure
0
5400 5500 5600 5700 5800 5900
Time, s
Internal pressure

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
Temperature, C
1200
1000
800
600
400
200
Temperature, C
0
3350 3450 3550 3650 3750
Time, s
3850 3950 4050
Integral LOCA tests
PARAMETR – FRA №3 (PWR type)
Temperature of cladding external surface
PARAMETR – FRA №4 (PWR type)
1400
1200
1000
800
600
400
200
0
3500 3600 3700 3800 3900 4000
Time, s
Temperature of cladding external surface
Pressure, MPa
Pressure, MPa
4
3,5
3
2,5
2
1,5
1
0,5
0
3350 3450 3550 3650 3750
Time, s
3850 3950 4050
4
3,5
3
2,5
2
1,5
1
0,5
Internal pressure
0
3500 3600 3700 3800 3900 4000
Time, s
Internal pressure

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
Temperature, °С
1000
900
800
700
600
500
400
300
200
100
0
2000 2200 2400 2600
Time, s
2800 3000 3200
Integral LOCA tests
BT-2
0
2000 2200 2400 2600
Time, s
2800 3000 3200
Temperature of cladding external surface Internal pressure
Pressure, MPa
8
7
6
5
4
3
2
1

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
Temperature of cladding external surface
Temperature, o C
1000
900
800
700
600
500
400
300
100 mm
400 mm
480 mm
000 mm
200
0 200 400 600
Time, s
800 1000 1200
Temperature of cladding external surface
Integral LOCA tests
IFA-650.6
IFA-650.11
Pressure, MPa
6
4
2
Rig
Fuel rod
Internal pressure
0
0 200 400 600
Time, s
800 1000 1200
Internal pressure

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
RAPTA-5.2
RAPTA-5.2
600
500
400
300
200
100
8
7
6
5
4
3
0
0 100 200 300
Experiment
400 500 600
Time to rupture
Pressure at burst
experiment = calculation
experiment = calculation
2
2 3 4 5
Experiment
6 7 8
Integral LOCA tests
RAPTA-5.2
1050
1000
950
900
850
800
750
experiment = calculation
700
700 750 800 850 900 950 1000 1050
Experiment
RAPTA-5.2
60
50
40
30
20
10
Temperature at burst
experiment = calculation
0
0 10 20 30
Experiment
40 50 60
Deformation in ruptured section

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
RIA experiments
E110 alloy irradiated at Novovoronezh and
Kola NPPs up to burnup 50 and 60 MWd/kgU
RAPTA-5.2
10
9
8
7
6
5
4
3
2
1
0
experiment = calculation
0 2 4 6 8 10
Experiment
Height average deformation
LHGR, W/cm
RAPTA-5.2
600000
400000
200000
80
70
60
50
40
30
20
#RT 6
0
0.00 0.05 0.10
Time, s
0.15 0.20
Linear heat generation rate
10
0
experiment = calculation
0 20 40
Experiment
60 80
Xenon and Krypton volume fraction

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
RIA experiments
The RAPTA-5.2 estimations of maximal fuel and
cladding temperatures and fuel peak enthalpy are in
good agreement with the same obtained by FRAP-
T6/VVER calculations.
RAPTA-5.2
1100
1050
1000
950
900
850
experiment = calculation
800
800 850 900 950 1000 1050 1100
FRAP-T6/VVER
Cladding peak temperature
RAPTA-5.2
RAPTA-5.2
2700
2500
2300
2100
1900
1700
experiment = calculation
1500
1500 1700 1900 2100 2300 2500 2700
FRAP-T6/VVER
200
190
180
170
160
150
140
130
120
Fuel peak temperature
110
100
experiment = calculation
100 120 140 160 180 200
FRAP-T6/VVER
Fuel peak enthalpy

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
SUMMARY
The verification results show that the code RAPTA-5.2 is a best estimate code.
The main directions of further development are:
1. The transition from deterministic calculations to probabilistic analysis.
2. Evolution of RAPTA-5.2 code for calculation of thermo-mechanical and corrosion
behavior of PWR fuel.
3. Development of new and perfection of existent models of the processes occurring in
the fuel rods.

Technical meeting on fuel behaviour and modelling under severe transient and LOCA conditions
October 18 – 21, 2011, Mito-city Ibaraki-ken, Japan
THANK YOU FOR YOUR ATTENTION