difis 2.0 – 3d finite element neutron kinetic code
DESCRIPTION
17 th AER Symposium on VVER Reactor Physics and Reactor Safety. DiFis 2.0 – 3D Finite Element Neutron Kinetic Code. A.I. Zhukov and A.M. Abdullayev NSC Kharkov Institute of Physics and Technology September 24 - 28, 2007 Yalta, Ukraine. Objective. - PowerPoint PPT PresentationTRANSCRIPT
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DiFis 2.0 – 3D Finite Element Neutron Kinetic Code
A.I. Zhukov and A.M. Abdullayev
NSC Kharkov Institute of Physics and Technology
September 24 - 28, 2007 Yalta, Ukraine
17th AER Symposium on VVER Reactor Physics and Reactor Safety
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Objective
Existing 1D kinetic codes too conservative
SNRCU intend to require 3D analysis for accidents with reactivity insertion (Control Rod Eject Accident and others)
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Background
Westinghouse PHOENIX-H code (XS)
Westinghouse Advanced Nodal Code (ANC-H)
Westinghouse 1D-3D neutron kinetic code TWINKLE (for PWR square FA lattice)
DiFis 1.0 – 3D FE steady-state code
FE methodology
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Nuclear Model
2 group approximation
111111
1 QDtv ra
6
12221111 1
iiiff CIQ
iiffii C
dt
dC 222111
222222
2 QDtv a
12 rQ
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Thermal Hydraulic Model
for fuel, gap, cladding
for coolant
Average Fuel Rod (one per assembly)
qdivt
h
j
jdivqt
p
z
hG
t
h
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Feedback Models
•PHOENIX-H provides all XS with feedback
•Moderator density correction includes:
a.Diffusion coefficient correction
b.Moderator absorption correction
c.Boron concentration correction
d.Spectrum correction
•Fuel temperature correction
•Xe, Sm, Pm correction
•Control Rod correction
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Finite Element Technique - 1
Set of simplex-functions
Set of linear functions
Expansion of fluxes into series over linear functions
yxj ,
zj
j
jj zyxFtzyx ,,,,
zyxzyxF jjj ,,,
1
5
6
4
2
3
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Finite Element Technique - 2
or
Weighted Residual Equations
dVFQ
dVFDtv
j
jra
1
11111
1
kjkkjkkjk QSLT 111ˆˆˆ
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Finite Element Technique - 3
1
6
2
3
4 5
1
6
2
3
4 5
7
8
910
1112
1314
15
16
17
18 19
20 21
22 23
24
1
6
43
2
3
4 5
7
8
910
1112
1314
15
16
17
18 19
20 21
22 23
24
26
27
28
25
2930
3132
3334
3536
3738
39
40
42
41
44 45 52 53
54
46 47
48 49
50 51
1
5
6
4
2
3
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Finite Element Technique - 4
Fuel Rod
NormallyFuel – 7 zonesGap – 2 zonesClad – 5 zonesAxial – 24 zones
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Code capabilities
•Core Power vs. time
•Spatial and time power distribution
•Spatial and time temperature distribution in
fuel, cladding and coolant
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Example of Steady-State Calculations
EOCRelative FA PowerANCDiFis-ANC
Max Err = 4.0%Rms Err = 1.6%
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Example of Transient Calculations - 1
Control Rod Eject Accident
Timeline
0 s 0.1 s 0.4 s 3.0 s
start finish all banks start to drop finish
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Example of Transient Calculations - 2Rod Cluster Worth 0.18%
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 0.5 1 1.5 2 2.5 3 3.5
time, s
Cor
e P
ower
Doppler onlyAll Banks drop
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Example of Transient Calculations - 3
Doppler only
FA under ejected RCCA
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Example of Transient Calculations - 4
All Banks drop
FA under ejected RCCA
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Example of Transient Calculations - 5
Doppler only
FA under ejected RCCA
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Example of Transient Calculations - 6
All Banks drop
FA under ejected RCCA
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Summary
1. DiFis 2.0 compatible with well-known codes such as PHOENIX-H and ANC-H
2. DiFis 2.0 provides accuracy ~4% (in compare with ANC) for steady-state calculations
3. DiFis 2.0 justification and benchmarking to be continued