Radially infinite, axially finite 3D geometry

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markdehart
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Radially infinite, axially finite 3D geometry

Post by markdehart » Tue Aug 28, 2018 2:36 am

I am trying to model a radially infinite axially finite core using Serpent 2.1.28. When I specify reflection I get the expected infinite lattice radially, but I am not getting black BCs on top and bottom. Universe 0 is a hexxprism so is finite in z. But the model is reflecting in as well. Is there something special I need to do to force black BCs on top and bottom?

Mark

Ville Valtavirta
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Re: Radially infinite, axially finite 3D geometry

Post by Ville Valtavirta » Tue Aug 28, 2018 2:03 pm

Hi Mark,

there should be no additional tricks required. You can try and see if the input below works for you and can serve as a starting point for figuring out what is wrong.

See also: http://serpent.vtt.fi/mediawiki/index.p ... conditions

-Ville

Code: Select all

% --- Pin with lower enrichment

pin 1
void   0.06000
fuel2  0.38000
void   0.38650
clad   0.45350
water

% --- Gd pin with lower enrichment

pin 2
void   0.06000
fuelG  0.38000
void   0.38650
clad   0.45350
water

% --- Pins with normal fuel

pin 3
void   0.06000
fuel1  0.38000
void   0.38650
clad   0.45350
water

% --- Central instrumentation tube

pin 16
water  0.440
clad   0.515
water

% --- Water pin

pin 99
water

% --- 4.37 wt.-% enriched fuel with 3.35 wt.-% of Gd2O3

mat fuelG   -10.85000 tmp 900 burn 1
92235.03c   -0.02580
92238.03c   -0.81630
8016.03c    -0.11910
64152.03c   -0.00007
64154.03c   -0.00083
64155.03c   -0.00560
64156.03c   -0.00790
64157.03c   -0.00605
64158.03c   -0.00967
64160.03c   -0.00861

% --- 4.2 wt.-% enriched fuel

mat fuel2   -10.45700 tmp 900 burn 1
92235.03c   -0.03702222
92238.03c   -0.84445932
8016.03c    -0.11851845

% --- 4.4 wt.-% enriched fuel

mat fuel1   -10.45700 tmp 900 burn 1
92235.03c   -0.03878507
92238.03c   -0.84269383
8016.03c    -0.1185211

% --- Clad (99-Zr / 1-Nb)

mat clad    -6.55000
 40090.03c  -5.01991E-01
 40091.03c  -1.10691E-01
 40092.03c  -1.71053E-01
 40094.03c  -1.77122E-01
 40096.03c  -2.91435E-02
 41093.03c  -0.01000

% --- Shroud tube (97.5-Zr / 2.5-Nb)

mat tube    -6.58000 tmp 600.0
 40090.03c  -4.94385E-01
 40091.03c  -1.09014E-01
 40092.03c  -1.68461E-01
 40094.03c  -1.74438E-01
 40096.03c  -2.87019E-02
 41093.03c  -0.025

% --- Water as coolant and moderator

mat water   -0.7554 tmp 550.0 moder lwtr 1001
 1001.03c    2.0
 8016.03c    1.0

therm lwtr lwj3.11t

% --- Lattice definition (could use symmetry)

lat l01 2 0.0 0.0 15 15 1.23
99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
  99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
   99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
    99 99 99 99 99 99 99 99 99 99 99 99 99  3 99
     99 99 99 99 99 99 99 99 99 99 99  3  3  3 99
      99 99 99 99 99 99 99 99 99  3  3  3  3  3 99
       99 99 99 99 99 99 99 16  3  3  3  3  2  1 99
        99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
         99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
          99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
           99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
            99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
             99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
              99 99 99 99 99 99 99 99 99 99 99 99 99 99 99

set usym l01 3 2 0.0 0.0 330 30

% --- Shroud tube limits

surf sH1 hexyc 0.0 0.0 7.100
surf sH2 hexyc 0.0 0.0 7.250

% --- Active column height 10 cm

surf sCB hexyprism 0.0 0.0 7.35 -5 5

% --- Radial cells for the assembly model

cell c1 uAss fill l01 -sH1
cell c2 uAss tube      sH1 -sH2
cell c3 uAss water     sH2

% --- Axial cells for the assembly

cell cA 0 fill uAss -sCB

% --- outside cell

cell 99 0 outside    sCB

/*****************
 ** Run options **
 *****************/

% --- Power results in average LHR of 150 W/cm
%     (assuming 126 rods and 248 cm length)

set power 4687200

% --- Neutron population and criticality cycles:

set pop 5000 100 50

% --- Reflective BC in xy, black in z

set bc 2 2 1  %  Finite: k-eff around  0.23 
%set bc 2 2 2  % Infinite: k-eff around  1.23 

% --- No group constant generation at first

set gcu -1

% --- Libraries

%set acelib "xsss2-beta/sss_endfb71.xsdata"

% --- Geometry and mesh plots:

plot 3 1154 1000
plot 2 1000 1470
mesh 3 1154 1000
mesh 2 1000 1470

User avatar
markdehart
Posts: 40
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Location: Idaho National Laboratory

Re: Radially infinite, axially finite 3D geometry

Post by markdehart » Tue Aug 28, 2018 6:06 pm

Okay, that's the problem. I was going from the manual that suggested that I should use "set bc 2" and it would automatically turn the finite axial BC to black. Now I'm getting what I expected using "set bc 2 2 1".

Thanks!

Mark

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