Difference between revisions of "Unstable 3D pin-cell burnup problem"

From Serpent Wiki
Jump to: navigation, search
(Created page with "In certain burnup problems such as long, axially symmetric 3D assemblies or fuel rods or large symmetric core geometries traditional Monte Carlo burnup schemes may run into in...")
 
Line 1: Line 1:
−
In certain burnup problems such as long, axially symmetric 3D assemblies or fuel rods or large symmetric core geometries traditional Monte Carlo burnup schemes may run into instabilities<ref name="DufekNSE09"/><ref name="DufekANE13a"/>.
+
In certain burnup problems such as long, axially symmetric 3D assemblies or fuel rods or large symmetric core geometries traditional Monte Carlo burnup schemes may run into instabilities<ref name="DufekNSE09"/><ref name="DufekANE13a"/>. This page describes the simulation of one such case first using the traditional burnup schemes (to showcase the instability) and then using a stable burnup scheme.
  
 +
== Problem description ==
 +
 +
<div class="toccolours mw-collapsible mw-collapsed" style="width:40em;">
 +
'''Base input for unstable 3D pin-cell problem'''
 +
<div class="mw-collapsible-content">
 +
<nowiki>/*****************
 +
** Run options **
 +
*****************/
 +
 +
% --- 50k neutrons per cycle, 100 inactive cycles
 +
 +
set pop 20000 1000 200
 +
 +
% --- 200 W/cm linear power
 +
 +
set power 60000
 +
 +
/*************************
 +
** Geometry definition **
 +
*************************/
 +
 +
% --- Fuel Pin definitions:
 +
 +
pin p1
 +
fuel  0.47
 +
void  0.48
 +
clad  0.54
 +
cool
 +
 +
% --- Lattice
 +
 +
lat l1  1  0.0 0.0 1 1 1.5
 +
p1
 +
 +
% --- Surrounding surfaces:
 +
 +
% Boundary of geometry:
 +
 +
surf 3 cuboid -0.75 0.75 -0.75 0.75 -160 160
 +
 +
% Lower boundary of fuel
 +
 +
surf 4 pz -150
 +
 +
% Upper boundary of fuel
 +
 +
surf 5 pz  150
 +
 +
% --- Cell definitions:
 +
 +
% Active fuel pin
 +
 +
cell  3  0  fill l1  -3  4 -5
 +
 +
% Coolant below active fuel (bottom reflector)
 +
 +
cell  4  0  cool    -3 -4
 +
 +
% Coolant above active fuel (top reflector)
 +
 +
cell  5  0  cool    -3  5
 +
 +
% outside world
 +
 +
cell 99  0  outside  3    % Outside world
 +
 +
% --- Reflective boundary conditions in XY, black in Z:
 +
 +
set bc 3 3 1
 +
 +
/**************************
 +
** Material definitions **
 +
**************************/
 +
 +
% --- Fuel material (4.85 % enrichment):
 +
 +
mat fuel    -10.283 vol 208.19 rgb 200 200 125
 +
92235.09c      0.016166667
 +
92238.09c      0.317166667
 +
8016.09c      0.666666667
 +
 +
% --- Cladding (Zr-4)
 +
 +
mat clad -6.56000E+00 rgb 180 180 180
 +
8016.06c    -1.19276E-03
 +
8017.06c    -4.82878E-07
 +
24050.06c    -4.16117E-05
 +
24052.06c    -8.34483E-04
 +
24053.06c    -9.64457E-05
 +
24054.06c    -2.44600E-05
 +
26054.06c    -1.12572E-04
 +
26056.06c    -1.83252E-03
 +
26057.06c    -4.30778E-05
 +
26058.06c    -5.83334E-06
 +
40090.06c    -4.97862E-01
 +
40091.06c    -1.09780E-01
 +
40092.06c    -1.69646E-01
 +
40094.06c    -1.75665E-01
 +
40096.06c    -2.89038E-02
 +
50112.06c    -1.27604E-04
 +
50114.06c    -8.83732E-05
 +
50115.06c    -4.59255E-05
 +
50116.06c    -1.98105E-03
 +
50117.06c    -1.05543E-03
 +
50118.06c    -3.35688E-03
 +
50119.06c    -1.20069E-03
 +
50120.06c    -4.59220E-03
 +
50122.06c    -6.63497E-04
 +
50124.06c    -8.43355E-04
 +
 +
% --- Coolant:
 +
 +
mat cool    -0.75 moder lwtr 1001 rgb 50 50 255
 +
1001.06c    0.666666667
 +
8016.06c    0.333333333
 +
 +
% --- Thermal scattering data for light water:
 +
 +
therm lwtr lwj3.11t</nowiki>
 +
</div>
 +
</div>
 +
 +
The base input for the problem is given above. The input describes a 300 cm long fuel rod in infinite lattice geometry. Axially the fuel rod is reflected from top and bottom with 10 cm water layers after which a black boundary condition is applied. The radial geometry is shown here:
 +
 +
[[File:Unstable3Dpin_geom1.png|frameless|200px|xy-plot of the pin-cell geometry.]]
 +
 +
== Unstable solution using explicit Euler's method ==
  
 
== References ==
 
== References ==

Revision as of 10:56, 29 September 2017

In certain burnup problems such as long, axially symmetric 3D assemblies or fuel rods or large symmetric core geometries traditional Monte Carlo burnup schemes may run into instabilities[1][2]. This page describes the simulation of one such case first using the traditional burnup schemes (to showcase the instability) and then using a stable burnup scheme.

Problem description

Base input for unstable 3D pin-cell problem 

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

% --- 50k neutrons per cycle, 100 inactive cycles

set pop 20000 1000 200 

% --- 200 W/cm linear power

set power 60000

/*************************
 ** Geometry definition **
 *************************/

% --- Fuel Pin definitions:

pin p1
fuel  0.47
void  0.48
clad  0.54
cool

% --- Lattice 

lat l1  1  0.0 0.0 1 1 1.5
p1

% --- Surrounding surfaces:

% Boundary of geometry:

surf 3 cuboid -0.75 0.75 -0.75 0.75 -160 160

% Lower boundary of fuel

surf 4 pz -150

% Upper boundary of fuel

surf 5 pz  150

% --- Cell definitions:

% Active fuel pin 

cell  3  0  fill l1  -3  4 -5

% Coolant below active fuel (bottom reflector)

cell  4  0  cool     -3 -4

% Coolant above active fuel (top reflector)

cell  5  0  cool     -3  5

% outside world 

cell 99  0  outside   3     % Outside world

% --- Reflective boundary conditions in XY, black in Z:

set bc 3 3 1

/**************************
 ** Material definitions **
 **************************/

% --- Fuel material (4.85 % enrichment):

mat fuel    -10.283 vol 208.19 rgb 200 200 125
92235.09c      0.016166667
92238.09c      0.317166667
8016.09c       0.666666667

% --- Cladding (Zr-4)

mat clad -6.56000E+00 rgb 180 180 180
 8016.06c     -1.19276E-03
 8017.06c     -4.82878E-07
24050.06c     -4.16117E-05
24052.06c     -8.34483E-04
24053.06c     -9.64457E-05
24054.06c     -2.44600E-05
26054.06c     -1.12572E-04
26056.06c     -1.83252E-03
26057.06c     -4.30778E-05
26058.06c     -5.83334E-06
40090.06c     -4.97862E-01
40091.06c     -1.09780E-01
40092.06c     -1.69646E-01
40094.06c     -1.75665E-01
40096.06c     -2.89038E-02
50112.06c     -1.27604E-04
50114.06c     -8.83732E-05
50115.06c     -4.59255E-05
50116.06c     -1.98105E-03
50117.06c     -1.05543E-03
50118.06c     -3.35688E-03
50119.06c     -1.20069E-03
50120.06c     -4.59220E-03
50122.06c     -6.63497E-04
50124.06c     -8.43355E-04

% --- Coolant:

mat cool     -0.75 moder lwtr 1001 rgb 50 50 255
 1001.06c    0.666666667
 8016.06c    0.333333333

% --- Thermal scattering data for light water:

therm lwtr lwj3.11t

The base input for the problem is given above. The input describes a 300 cm long fuel rod in infinite lattice geometry. Axially the fuel rod is reflected from top and bottom with 10 cm water layers after which a black boundary condition is applied. The radial geometry is shown here:

xy-plot of the pin-cell geometry.

Unstable solution using explicit Euler's method

References

  1. ^ Dufek, J. and Hoogenboom, E. "Numerical Stability of Existing Monte Carlo Burnup Codes in Cycle Calculations of Critical Reactors", Nucl. Sci. Eng., 162 (2009) 307-311
  2. ^ Dufek, J. et al. "Numerical stability of the predictor–corrector method in Monte Carlo burnup calculations of critical reactors", Ann. Nucl. Energy, 56 (2013) 34-38
Retrieved from "https://serpent.vtt.fi/mediawiki/index.php?title=Unstable_3D_pin-cell_burnup_problem&oldid=3826"