Dear Serpent users
I'm new to Serpent and I'm attempting to do a 2D hexagonal lattice calculation. It represents a fuel assembly of 7 hexagonal rods to make a bigger fuel assembly in hexagonal geometry. There are lots of lattice example calculations, however these only seem to be pin cell calculations whereas I'm using hexagons, each of which have their own concentric circles to represent the fuel/moderator regions etc. Based on the .png file created, I seem to be able to get the single central hexagon looking as it should but there seems to be a problem with the lattice calculation. I've attached a picture of the geometry I am trying to create, and the .png file of what is created when I run serpent. The only difference is that the picture shows coolant channels around each hexagonal fuel rod, but I have approximated this to an additional hexagonal surface around each fuel rod which contains coolant. The areas are the same. Here is my input file:
%  DRAGON fuel Assembly 
set title "dragon"
% 
% Geometry
% 
%  Coated particle:
particle 1
fuel 0.0336
PyC 0.0436
matrix
%  Spherical lattice cell containing particles in a graphite matrix, using implicit model, matrix material is universe number 0, particle is universe number 1, the particle matrix region is universe 2, and the entire fuel rod is universe 3
surf 10 inf
cell 0 10 matrix 10
disp 2 10 0.26 0.0436 1
%  Hexagonal fuel rod, containing annuli of moderator, fuel, coolant, note that there are air gaps between the fuel and moderator
surf 1 cyl 0.0 0.0 0.3965 %  Circular surface containing central purge channel
surf 2 cyl 0.0 0.0 1.1235 %  Circular surface containing graphite spine
surf 3 cyl 0.0 0.0 1.149 %  Circular surface containing air gap between spine and fuel
surf 4 cyl 0.0 0.0 2.207 %  Circular surface containing fuel
surf 5 cyl 0.0 0.0 2.2245 %  Circular surface containing air gap between fuel and sleeve
surf 6 hexxc 0.0 0.0 2.75 %  Hexagonal surface containing graphite sleeve
surf 7 hexxc 0.0 0.0 2.82 %  Hexagonal surface containing coolant flow, where 6 coolant channels surrounding the hexagonal rod have been approximated to a single hexagonal annulus
cell 1 3 purgeflow 1
cell 2 3 spine 1 2
cell 3 3 agap1 2 3
cell 4 3 fill 10 3 4
cell 5 3 agap2 4 5
cell 6 3 sleeve 5 6
cell 7 3 coolant 6 7
cell 8 3 outside
%  Empty lattice position
%surf 8 hexxc 8.46 4.88 2.82 %  Hexagonal surface containing coolant flow, where 6 coolant
%cell 8 4 outside 8
%surf 9 hexxc 8.46 4.88 2.82 %  Hexagonal surface containing coolant flow, where 6 coolant
%cell 9 4 outside 8
%  Hexagonal lattice, of 7 hexagonal fuel rods, universe 4, pitch is 18.33cm, flattoflat is 15.87cm
lat 5 3 0.0 0.0 3 3 18.75 %16.94
4 3 3
3 3 3
3 3 4
surf 11 hexyc 0.0 0.0 8.12 %7.935
cell 10 0 fill 5 9
cell 11 0 outside 9
% 
% Material data:
% 
%  Fuel: (UC2, ThC2) kernel
mat fuel 8.25
92234.09c 4.59996E04
92235.09c 3.56497E02
92236.09c 9.58324E05
92238.09c 2.12748E03
90232.09c 5.27906E01
6012.09c 4.33761E01
%  Pyrolytic carbon layer: surrounding fuel
mat PyC 1.85 moder grph 6000
6000.09c 9.27565E02
%  Graphite matrix: containing fuel particles
mat matrix 1.7 moder grph 6000
6000.09c 8.52357E02
%  Graphite spine: contained within fuel cartridge
mat spine 1.75 moder grph 6000
6000.09c 8.77426E02
%  Hexagonal graphite sleeve: surroudning
mat sleeve 1.775 moder grph 6000
6000.09c 8.89961E02
%  Thermal scattering data: required for moderators
therm grph gre7.00t
%  Air gap between spine and fuel: Assumed to be 100% nitrogen
mat agap1 1.7627E05
7014.09c 1.7627E05
%  Air gap between fuel and sleeve: Assumed to be 100% nitrogen
mat agap2 1.7627E05
7014.09c 1.7627E05
%  Fission product purge flow: Assumed to be 100% nitrogen
mat purgeflow 1.7627E05
7014.09c 1.7627E05
%  Coolant channel: He4
mat coolant 1.63E04
2004.09c 1.63E04
% 
% Calculation parameters
% 
%  Cross section library file path:
set acelib "/home/es2517/Documents/serpent/xsdata/jeff31/sss_jeff31u.xsdata"
%  Periodic boundary condition:
set bc 2
%  Group constant generation:
% universe = 0 (homogenization over all space)
% symmetry = 12
% 2group structure (group boundary at 0.625 eV)
set gcu 0
set sym 0
set nfg 2 0.625E6
%  Neutron population and criticality cycles:
set pop 2000 500 20
%  Geometry and mesh plots:
plot 3 500 500
mesh 3 500 500
%  Detector energy grid (uniform lethargy):
ene 1 3 1000 1E9 12.0
%  Flux per lethargy:
%det 1 de 1 dt 3
%  Differential capture, fission and production spectra:
%det 2 de 1 dt 2 dr 2 void
%det 3 de 1 dt 2 dr 6 void
%det 4 de 1 dt 2 dr 7 void
%  Integral capture, fission and production spectra:
%det 5 de 1 dt 1 dr 2 void
%det 6 de 1 dt 1 dr 6 void
%det 7 de 1 dt 1 dr 7 void
% 
I've defined the fuel rods as universe 3, universe 4 is to account for the two empty cells in the lattice. Universe 5 is the lattice and universe 0 describes the surface and cell containing the lattice. When I run I get this error:
Input error:
Only centred hexagonal repeated boundaries allowed
Any input would be much appreciated. As I said, I'm new to serpent.
Thank you
Emma
Hexagonal lattice calculation
Hexagonal lattice calculation
 Attachments

 dragon_fuel_element.png (34.57 KiB) Viewed 1282 times

 2d_dragon_fuel_assembly_v1_geom1.png (3.09 KiB) Viewed 1282 times
 Jaakko Leppänen
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 Posts: 2442
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 Location: Espoo, Finland
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Re: Hexagonal lattice calculation
I'm getting some different errors (universe 4 has no cells) trying to run the input. Are you sure you posted the right input?
 Jaakko

 Posts: 34
 Joined: Tue Jul 19, 2016 3:15 pm
 Security question 1: No
 Security question 2: 40
Re: Hexagonal lattice calculation
Hi Emma,
I think the attached is something a bit more like what you're looking for. I removed the implicit particle treatment though as it isn't supported in the latest version.
Cheers,
Paul
I think the attached is something a bit more like what you're looking for. I removed the implicit particle treatment though as it isn't supported in the latest version.
Code: Select all
%  DRAGON fuel Assembly 
set title "dragon"
% 
% Geometry
% 
%  Spherical lattice cell containing particles in a graphite matrix, using implicit model, matrix material is universe number 0, particle is universe number 1, the particle matrix region is universe 2, and the entire fuel rod is universe 3
%  Hexagonal fuel rod, containing annuli of moderator, fuel, coolant, note that there are air gaps between the fuel and moderator
surf 1 cyl 0.0 0.0 0.3965 %  Circular surface containing central purge channel
surf 2 cyl 0.0 0.0 1.1235 %  Circular surface containing graphite spine
surf 3 cyl 0.0 0.0 1.149 %  Circular surface containing air gap between spine and fuel
surf 4 cyl 0.0 0.0 2.207 %  Circular surface containing fuel
surf 5 cyl 0.0 0.0 2.2245 %  Circular surface containing air gap between fuel and sleeve
surf 6 hexxc 0.0 0.0 2.75 %  Hexagonal surface containing graphite sleeve
surf 7 hexxc 0.0 0.0 2.82 %  Hexagonal surface containing coolant flow, where 6 coolant channels surrounding the hexagonal rod have been approximated to a single hexagonal annulus
surf 8 hexxc 0.0 0.0 10% bounding assembly surface
% Define the assembly
cell 1 1 purgeflow 1
cell 2 1 spine 1 2
cell 3 1 agap 2 3
cell 4 1 fuel 3 4
cell 5 1 agap 4 5
cell 6 1 sleeve 5 6
cell 7 1 coolant 6 7
% Define the void assembly
cell 8 4 void 7
cell 10 0 fill 5 8
cell 11 0 outside 8
%  Hexagonal lattice, of 7 hexagonal fuel rods plus void surroundings
lat 5 2 0.0 0.0 5 5 5.64%16.94
4 4 4 4 4
4 4 1 1 4
4 1 1 1 4
4 1 1 4 4
4 4 4 4 4
% 
% Material data:
% 
%  Fuel: (UC2, ThC2) kernel
mat fuel 8.25
92234.09c 4.59996E04
92235.09c 3.56497E02
92236.09c 9.58324E05
92238.09c 2.12748E03
90232.09c 5.27906E01
6012.09c 4.33761E01
%  Pyrolytic carbon layer: surrounding fuel
%mat PyC 1.85 moder grph 6000
% 6000.09c 9.27565E02
%  Graphite matrix: containing fuel particles
%mat matrix 1.7 moder grph 6000
% 6000.09c 8.52357E02
%  Graphite spine: contained within fuel cartridge
mat spine 1.75 moder grph 6000
6000.09c 8.77426E02
%  Hexagonal graphite sleeve: surroudning
mat sleeve 1.775 moder grph 6000
6000.09c 8.89961E02
%  Thermal scattering data: required for moderators
therm grph gre7.00t
%  Air gap between spine and fuel: Assumed to be 100% nitrogen
mat agap 1.7627E05
7014.09c 1.7627E05
%  Fission product purge flow: Assumed to be 100% nitrogen
mat purgeflow 1.7627E05
7014.09c 1.7627E05
%  Coolant channel: He4
mat coolant 1.63E04
2004.09c 1.63E04
% 
% Calculation parameters
% 
%  Cross section library file path:
%set acelib "/home/es2517/Documents/serpent/xsdata/jeff31/sss_jeff31u.xsdata"
set acelib "/usr/software/mcnplib/SERPENT/XSdata_endfb7/sss_endfb7u.xsdata"
%  Periodic boundary condition:
set bc 1
%  Group constant generation:
% universe = 0 (homogenization over all space)
% symmetry = 12
% 2group structure (group boundary at 0.625 eV)
set gcu 0
set sym 0
set nfg 2 0.625E6
%  Neutron population and criticality cycles:
set pop 10000 500 200
%  Geometry and mesh plots:
plot 3 500 500
mesh 3 500 500
%  Detector energy grid (uniform lethargy):
ene 1 3 1000 1E9 12.0
%  Flux per lethargy:
%det 1 de 1 dt 3
%  Differential capture, fission and production spectra:
%det 2 de 1 dt 2 dr 2 void
%det 3 de 1 dt 2 dr 6 void
%det 4 de 1 dt 2 dr 7 void
%  Integral capture, fission and production spectra:
%det 5 de 1 dt 1 dr 2 void
%det 6 de 1 dt 1 dr 6 void
%det 7 de 1 dt 1 dr 7 void
% 
Paul
 Attachments

 paul_dragon_geom1.png (5.62 KiB) Viewed 1273 times