Tutorial

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Revision as of 15:29, 12 September 2017 by Ville Valtavirta (Talk | contribs) (Running the input)

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This page is the beginning of a hands-on tutorial in Serpent that will walk you through the creation of simple pin-cell and assembly geometry models and the use of those models for some reactor physics simulations.

Prerequisite

Compiled version of Serpent 2.

This tutorial assumes that you can run Serpent 2 simply by typing sss2 in your terminal, i.e. you either have the executable in your PATH or have created an alias for the executable. If this is not the case, you'll need to replace the sss2 run-commands with the full path to your executable.

Cross section libraries.

This tutorial assumes that you have defined a default cross section directory file for Serpent using the SERPENT_ACELIB environment variable (see the notes of set acelib). If this is not the case, you'll need to give the path to a cross section directory file in the input using set acelib.

Basics of Serpent input

Explain different (typical) parts such as:

  • Material definitions
  • Geometry definitions
  • Run parameters/options

Infinite homogeneous model

Overview

The first model in this tutorial is the simplest geometry model one can imagine: an infinite homogeneous system consisting of a single material. Here the infinite material is 4.0 wt-% enriched uranium with a density of 10.1 g/cm3.

We will use the infinite homogeneous system example for three tasks:

  1. Finding the critical enrichment of an infinite uranium system.
  2. Tallying the neutron energy spectrum in the critical infinite uranium system.
  3. Testing the effect of added neutron moderation on the multiplication factor and energy spectrum of the system.

Input

The input of the model is shown below and consists of only five definitions:

  1. Defining the single material, which is called fuel in this example.
  2. Defining the geometry by
    1. Defining an "infinite" surface, i.e. a surface enclosing all of space. The surface name is s1 in this example.
    2. Defining two geometry cells: One containing the material fuel and the other being defined as an outside cell.
  3. Setting up any other run parameters, here simply setting the neutron population that is to be simulated.

Colors in the input correspond to:

  • Comments: These are ignored by Serpent.
  • Control words: A constantly updating list of control words can be found in the Input syntax manual. Everything between two control words that is not a comment is treated as a parameter to the first control word.
  • Name definitions: Name definitions for the various Serpent objects can contain characters and numbers and are used for referencing certain objects in other definitions.
  • Name references: References to named objects defined in the input. Name references can be made even if the name definition has not been made yet as long as the name will be defined later in the input.

Input for infinite homogeneous model

% --- Very simple infinite homogeneous geometry for Serpent tutorial

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

% --- Fuel material (4.0 wt-% enriched uranium), density 10.1 g/cm3

mat fuel     -10.1
92235.03c    -0.04 
92238.03c    -0.96

/************************
 * Geometry definitions *
 ************************/

% --- "Surface" at infinity

surf s1 inf

% --- Cell c1 belongs to the base universe 0, contains the material fuel
%     and covers everything inside surface s1

cell c1 0 fuel      -s1

% --- Cell c2 belongs to the base universe 0, is defined as an "outside" cell
%     and covers everything outside surface s1

cell c2 0 outside    s1

/******************
 * Run parameters *
 ******************/

% --- Neutron population: 5000 neutrons per cycle, 100 active / 20 inactive cycles

set pop 5000 100 20

Running the input

Copy and paste the input to a file named infinite on your computer.

Simply run the input from terminal, by being in the same directory as the input-file and executing

sss2 infinite

If you compiled Serpent with OpenMP libraries for parallel computing, you can run the input with multiple OpenMP threads to use more than one processor:

sss2 -omp N infinite

where N is the number of OpenMP threads you want to use and can be set to, e.g. the number of available processor cores.

An example of the expected output is given below, although you should note that the statistical nature of the Monte Carlo methods means that you will not get exactly same values for the k-effective:

Expected output for the infinite system

  _                   .-=-.           .-=-.          .-==-.       
 { }      __        .' O o '.       .' O o '.       /  -<' )--<   
 { }    .' O'.     / o .-. O \     / o .-. O \     /  .---`       
 { }   / .-. o\   /O  /   \  o\   /O  /   \  o\   /O /            
  \ `-` /   \ O`-'o  /     \  O`-'o  /     \  O`-`o /             
   `-.-`     '.____.'       `._____.'       `.____.'              

Serpent 2 beta

A Continuous-energy Monte Carlo Reactor Physics Burnup Calculation Code

 - Version 2.1.29 (June 12, 2017) -- Contact: serpent@vtt.fi

 - Reference: J. Leppanen, et al. "The Serpent Monte Carlo code: Status,
              development and applications in 2013." Ann. Nucl. Energy,
              82 (2015) 142-150.

 - Compiled Jun 19 2017 10:21:15

 - MPI Parallel calculation mode not available

 - OpenMP Parallel calculation mode available

 - Geometry and mesh plotting available

 - Default data path set to: "/home/vvvillehe/XSdata/"

Begin calculation on Mon Sep 11 12:51:14 2017

Reading input file "infinite"...

Checking duplicate input definitions...
OK.

Creating geometry...
OK.

Counting geometry zones...

Processing cells...
OK.

Linking materials to geometry...
OK.

Counting cells...
OK.

Processing data for group constant generation:

 - 70 energy groups in micro-group structure
 - 2 energy groups in macro-group structure
 - B1 fundamental mode calculation is not run
 - Group constants generated in 1 universes
 - Discontinuity factors are not calculated
 - Pin-power distributions are not calculated
 - Albedos are not calculated
 - Poison cross sections are not calculated

Reading ACE directory files...
OK.

Adding nuclides in material fuel...

Nuclide  92235.03c -- uranium 235 at 300K (U-235)
Nuclide  92238.03c -- uranium 238 at 300K (U-238)

Checking data and printing output...
OK.


***** Mon Sep 11 12:51:15 2017 (seed = 1505123474)
Warning message from function ProcessNuclides:

Minimum photon cross section energy 1.000000E+37 MeV is
above the energy grid minimum 1.000000E-03 MeV.
The energy grid minimum is set to 1.000000E+37 MeV.
Possible changes in energy cutoff cards (warned if any).


***** Mon Sep 11 12:51:15 2017 (seed = 1505123474)
Warning message from function ProcessNuclides:

Photon energy cutoff 1.000000E-03 MeV is changed to 1.000000E+37.


Generating unionize energy grids...

Adding points:

 92235.03c -- Points added in neutron grid: 30884
 92238.03c -- Points added in neutron grid: 64918

Generating unionized energy grid:

 - Unionization performed without grid thinning
   between 1.00E-11 and 20.0 MeV.

 - Final neutron grid size: 95836 points.

 - 2.12 Mb of memory allocated for grid data

OK.

Processing cross sections and ENDF reaction laws...

Nuclide  92235.03c -- uranium 235 at 300K (U-235)
Nuclide  92238.03c -- uranium 238 at 300K (U-238)

SUMMARY -- 2 nuclides included in calculation:

 - 2 transport nuclides
 - Neutron energy cut-offs at 1.00E-11 and 20.0 MeV
 - 88 transport reactions
 - 2 special reactions
 - 18.07 Mb of memory allocated for data

Normalizing compositions and processing mixtures...
OK.

Allocating memory for macroscopic cross section data...
OK.

Allocating memory for particle structures...
OK.

Calculating maximum densities...
OK.

Performing density cut-off...
OK.

Sorting material-wise reaction lists:

   0% complete
 100% complete

Calculating macroscopic cross sections:

   0% complete
 100% complete

Calculating DT neutron majorant cross section:

   0% complete
 100% complete

Clearing results and statistics...
OK.

Sampling initial source...
OK.

Inactive cycle   1 /  20: k-eff = 1.00000
Inactive cycle   2 /  20: k-eff = 0.83420
Inactive cycle   3 /  20: k-eff = 0.79549
Inactive cycle   4 /  20: k-eff = 0.87011
Inactive cycle   5 /  20: k-eff = 0.81582
Inactive cycle   6 /  20: k-eff = 0.83654
Inactive cycle   7 /  20: k-eff = 0.81429
Inactive cycle   8 /  20: k-eff = 0.88334
Inactive cycle   9 /  20: k-eff = 0.84641
Inactive cycle  10 /  20: k-eff = 0.88078
Inactive cycle  11 /  20: k-eff = 0.82141
Inactive cycle  12 /  20: k-eff = 0.83916
Inactive cycle  13 /  20: k-eff = 0.85225
Inactive cycle  14 /  20: k-eff = 0.84424
Inactive cycle  15 /  20: k-eff = 0.82836
Inactive cycle  16 /  20: k-eff = 0.80235
Inactive cycle  17 /  20: k-eff = 0.84424
Inactive cycle  18 /  20: k-eff = 0.85251
Inactive cycle  19 /  20: k-eff = 0.81653
Inactive cycle  20 /  20: k-eff = 0.83237

----- Begin active cycles -----

------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    1 / 100  Source neutrons :  5177

Running time :                  0:00:09
Estimated running time :        -:--:--
Estimated running time left :   -:--:--

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.86184 +/- 0.00000  [0.86184  0.86184]
k-eff (implicit)  = 0.84234 +/- 0.00000  [0.84234  0.84234]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    2 / 100  Source neutrons :  4873

Running time :                  0:00:09
Estimated running time :        -:--:--
Estimated running time left :   -:--:--

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.85090 +/- 0.01095  [0.82944  0.87235]
k-eff (implicit)  = 0.83921 +/- 0.00313  [0.83308  0.84535]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    3 / 100  Source neutrons :  4979

Running time :                  0:00:10
Estimated running time :        -:--:--
Estimated running time left :   -:--:--

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84607 +/- 0.00795  [0.83049  0.86165]
k-eff (implicit)  = 0.83824 +/- 0.00205  [0.83421  0.84226]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    4 / 100  Source neutrons :  4980

Running time :                  0:00:10
Estimated running time :        -:--:--
Estimated running time left :   -:--:--

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84282 +/- 0.00649  [0.83010  0.85555]
k-eff (implicit)  = 0.83595 +/- 0.00271  [0.83063  0.84127]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    5 / 100  Source neutrons :  5072

Running time :                  0:00:11
Estimated running time :        0:00:57
Estimated running time left :   0:00:46

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84327 +/- 0.00505  [0.83338  0.85317]
k-eff (implicit)  = 0.83419 +/- 0.00274  [0.82882  0.83956]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    6 / 100  Source neutrons :  4895

Running time :                  0:00:11
Estimated running time :        0:00:57
Estimated running time left :   0:00:45

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84061 +/- 0.00491  [0.83100  0.85023]
k-eff (implicit)  = 0.83488 +/- 0.00234  [0.83029  0.83946]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    7 / 100  Source neutrons :  5060

Running time :                  0:00:12
Estimated running time :        0:00:57
Estimated running time left :   0:00:45

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84013 +/- 0.00417  [0.83195  0.84831]
k-eff (implicit)  = 0.83563 +/- 0.00212  [0.83149  0.83978]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    8 / 100  Source neutrons :  5034

Running time :                  0:00:12
Estimated running time :        0:00:57
Estimated running time left :   0:00:44

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84049 +/- 0.00363  [0.83337  0.84760]
k-eff (implicit)  = 0.83605 +/- 0.00188  [0.83237  0.83974]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle    9 / 100  Source neutrons :  5141

Running time :                  0:00:12
Estimated running time :        0:00:56
Estimated running time left :   0:00:43

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84340 +/- 0.00433  [0.83491  0.85189]
k-eff (implicit)  = 0.83678 +/- 0.00181  [0.83323  0.84032]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   10 / 100  Source neutrons :  4689

Running time :                  0:00:13
Estimated running time :        0:00:56
Estimated running time left :   0:00:43

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84034 +/- 0.00494  [0.83067  0.85002]
k-eff (implicit)  = 0.83686 +/- 0.00162  [0.83368  0.84003]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   11 / 100  Source neutrons :  5340

Running time :                  0:00:13
Estimated running time :        0:00:56
Estimated running time left :   0:00:42

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84286 +/- 0.00513  [0.83281  0.85291]
k-eff (implicit)  = 0.83725 +/- 0.00152  [0.83428  0.84022]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   12 / 100  Source neutrons :  4906

Running time :                  0:00:14
Estimated running time :        0:00:56
Estimated running time left :   0:00:42

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84360 +/- 0.00474  [0.83432  0.85289]
k-eff (implicit)  = 0.83862 +/- 0.00195  [0.83480  0.84243]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   13 / 100  Source neutrons :  5000

Running time :                  0:00:14
Estimated running time :        0:00:56
Estimated running time left :   0:00:41

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84423 +/- 0.00440  [0.83560  0.85286]
k-eff (implicit)  = 0.83770 +/- 0.00201  [0.83376  0.84164]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   14 / 100  Source neutrons :  4759

Running time :                  0:00:15
Estimated running time :        0:00:56
Estimated running time left :   0:00:41

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84184 +/- 0.00473  [0.83257  0.85111]
k-eff (implicit)  = 0.83771 +/- 0.00186  [0.83406  0.84135]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   15 / 100  Source neutrons :  5270

Running time :                  0:00:15
Estimated running time :        0:00:56
Estimated running time left :   0:00:40

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84268 +/- 0.00448  [0.83390  0.85147]
k-eff (implicit)  = 0.83771 +/- 0.00173  [0.83432  0.84111]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   16 / 100  Source neutrons :  4903

Running time :                  0:00:16
Estimated running time :        0:00:56
Estimated running time left :   0:00:40

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84238 +/- 0.00420  [0.83414  0.85062]
k-eff (implicit)  = 0.83794 +/- 0.00164  [0.83474  0.84115]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   17 / 100  Source neutrons :  5066

Running time :                  0:00:16
Estimated running time :        0:00:56
Estimated running time left :   0:00:39

Estimated relative CPU usage :   100.2%

k-eff (analog)    = 0.84277 +/- 0.00397  [0.83499  0.85054]
k-eff (implicit)  = 0.83708 +/- 0.00176  [0.83363  0.84054]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   18 / 100  Source neutrons :  4864

Running time :                  0:00:17
Estimated running time :        0:00:56
Estimated running time left :   0:00:39

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84183 +/- 0.00386  [0.83427  0.84939]
k-eff (implicit)  = 0.83702 +/- 0.00166  [0.83376  0.84028]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   19 / 100  Source neutrons :  5195

Running time :                  0:00:17
Estimated running time :        0:00:56
Estimated running time left :   0:00:38

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84269 +/- 0.00375  [0.83534  0.85003]
k-eff (implicit)  = 0.83771 +/- 0.00172  [0.83435  0.84107]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   20 / 100  Source neutrons :  4758

Running time :                  0:00:18
Estimated running time :        0:00:56
Estimated running time left :   0:00:38

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84138 +/- 0.00379  [0.83396  0.84880]
k-eff (implicit)  = 0.83786 +/- 0.00163  [0.83465  0.84106]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   21 / 100  Source neutrons :  5296

Running time :                  0:00:18
Estimated running time :        0:00:56
Estimated running time left :   0:00:37

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84250 +/- 0.00377  [0.83511  0.84989]
k-eff (implicit)  = 0.83784 +/- 0.00155  [0.83480  0.84089]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   22 / 100  Source neutrons :  4817

Running time :                  0:00:19
Estimated running time :        0:00:56
Estimated running time left :   0:00:37

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84208 +/- 0.00362  [0.83498  0.84918]
k-eff (implicit)  = 0.83827 +/- 0.00154  [0.83525  0.84130]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   23 / 100  Source neutrons :  5027

Running time :                  0:00:19
Estimated running time :        0:00:56
Estimated running time left :   0:00:36

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84189 +/- 0.00347  [0.83510  0.84868]
k-eff (implicit)  = 0.83835 +/- 0.00148  [0.83545  0.84124]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   24 / 100  Source neutrons :  4986

Running time :                  0:00:20
Estimated running time :        0:00:56
Estimated running time left :   0:00:36

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84162 +/- 0.00333  [0.83509  0.84814]
k-eff (implicit)  = 0.83830 +/- 0.00141  [0.83553  0.84107]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   25 / 100  Source neutrons :  5009

Running time :                  0:00:20
Estimated running time :        0:00:56
Estimated running time left :   0:00:35

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84143 +/- 0.00320  [0.83516  0.84770]
k-eff (implicit)  = 0.83851 +/- 0.00137  [0.83582  0.84120]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   26 / 100  Source neutrons :  5049

Running time :                  0:00:21
Estimated running time :        0:00:56
Estimated running time left :   0:00:35

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84157 +/- 0.00308  [0.83554  0.84760]
k-eff (implicit)  = 0.83871 +/- 0.00133  [0.83609  0.84132]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   27 / 100  Source neutrons :  5140

Running time :                  0:00:21
Estimated running time :        0:00:56
Estimated running time left :   0:00:35

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84258 +/- 0.00313  [0.83645  0.84871]
k-eff (implicit)  = 0.83871 +/- 0.00128  [0.83620  0.84123]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   28 / 100  Source neutrons :  4907

Running time :                  0:00:22
Estimated running time :        0:00:56
Estimated running time left :   0:00:34

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84294 +/- 0.00303  [0.83699  0.84888]
k-eff (implicit)  = 0.83878 +/- 0.00124  [0.83635  0.84120]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   29 / 100  Source neutrons :  4885

Running time :                  0:00:22
Estimated running time :        0:00:57
Estimated running time left :   0:00:34

Estimated relative CPU usage :    99.8%

k-eff (analog)    = 0.84259 +/- 0.00295  [0.83681  0.84837]
k-eff (implicit)  = 0.83902 +/- 0.00122  [0.83663  0.84140]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   30 / 100  Source neutrons :  5101

Running time :                  0:00:23
Estimated running time :        0:00:57
Estimated running time left :   0:00:33

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84283 +/- 0.00286  [0.83723  0.84843]
k-eff (implicit)  = 0.83909 +/- 0.00118  [0.83678  0.84140]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   31 / 100  Source neutrons :  4844

Running time :                  0:00:23
Estimated running time :        0:00:56
Estimated running time left :   0:00:33

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84220 +/- 0.00284  [0.83665  0.84776]
k-eff (implicit)  = 0.83927 +/- 0.00115  [0.83700  0.84153]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   32 / 100  Source neutrons :  5069

Running time :                  0:00:24
Estimated running time :        0:00:56
Estimated running time left :   0:00:32

Estimated relative CPU usage :   100.2%

k-eff (analog)    = 0.84197 +/- 0.00276  [0.83657  0.84737]
k-eff (implicit)  = 0.83902 +/- 0.00114  [0.83678  0.84126]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   33 / 100  Source neutrons :  5146

Running time :                  0:00:24
Estimated running time :        0:00:57
Estimated running time left :   0:00:32

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.84248 +/- 0.00272  [0.83715  0.84782]
k-eff (implicit)  = 0.83844 +/- 0.00125  [0.83598  0.84089]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   34 / 100  Source neutrons :  4777

Running time :                  0:00:25
Estimated running time :        0:00:57
Estimated running time left :   0:00:32

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84184 +/- 0.00272  [0.83652  0.84717]
k-eff (implicit)  = 0.83807 +/- 0.00127  [0.83558  0.84056]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   35 / 100  Source neutrons :  5022

Running time :                  0:00:25
Estimated running time :        0:00:57
Estimated running time left :   0:00:31

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84134 +/- 0.00268  [0.83608  0.84660]
k-eff (implicit)  = 0.83781 +/- 0.00126  [0.83534  0.84028]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   36 / 100  Source neutrons :  4947

Running time :                  0:00:26
Estimated running time :        0:00:57
Estimated running time left :   0:00:31

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84063 +/- 0.00270  [0.83533  0.84593]
k-eff (implicit)  = 0.83794 +/- 0.00123  [0.83553  0.84035]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   37 / 100  Source neutrons :  5137

Running time :                  0:00:26
Estimated running time :        0:00:57
Estimated running time left :   0:00:30

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.84056 +/- 0.00263  [0.83540  0.84571]
k-eff (implicit)  = 0.83793 +/- 0.00120  [0.83559  0.84028]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   38 / 100  Source neutrons :  5042

Running time :                  0:00:27
Estimated running time :        0:00:57
Estimated running time left :   0:00:30

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84067 +/- 0.00256  [0.83565  0.84570]
k-eff (implicit)  = 0.83794 +/- 0.00117  [0.83566  0.84023]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   39 / 100  Source neutrons :  5086

Running time :                  0:00:27
Estimated running time :        0:00:57
Estimated running time left :   0:00:29

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84116 +/- 0.00254  [0.83617  0.84614]
k-eff (implicit)  = 0.83800 +/- 0.00114  [0.83577  0.84022]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   40 / 100  Source neutrons :  4784

Running time :                  0:00:28
Estimated running time :        0:00:57
Estimated running time left :   0:00:29

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84069 +/- 0.00252  [0.83574  0.84563]
k-eff (implicit)  = 0.83796 +/- 0.00111  [0.83579  0.84013]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   41 / 100  Source neutrons :  5005

Running time :                  0:00:28
Estimated running time :        0:00:57
Estimated running time left :   0:00:28

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.84026 +/- 0.00250  [0.83537  0.84516]
k-eff (implicit)  = 0.83810 +/- 0.00109  [0.83597  0.84024]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   42 / 100  Source neutrons :  5001

Running time :                  0:00:29
Estimated running time :        0:00:57
Estimated running time left :   0:00:28

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83986 +/- 0.00247  [0.83502  0.84470]
k-eff (implicit)  = 0.83831 +/- 0.00108  [0.83619  0.84044]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   43 / 100  Source neutrons :  4897

Running time :                  0:00:29
Estimated running time :        0:00:57
Estimated running time left :   0:00:27

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83908 +/- 0.00253  [0.83411  0.84405]
k-eff (implicit)  = 0.83816 +/- 0.00107  [0.83606  0.84025]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   44 / 100  Source neutrons :  5279

Running time :                  0:00:29
Estimated running time :        0:00:57
Estimated running time left :   0:00:27

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83936 +/- 0.00249  [0.83448  0.84424]
k-eff (implicit)  = 0.83805 +/- 0.00105  [0.83599  0.84011]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   45 / 100  Source neutrons :  4871

Running time :                  0:00:30
Estimated running time :        0:00:57
Estimated running time left :   0:00:26

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83914 +/- 0.00245  [0.83435  0.84393]
k-eff (implicit)  = 0.83832 +/- 0.00106  [0.83624  0.84041]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   46 / 100  Source neutrons :  5106

Running time :                  0:00:30
Estimated running time :        0:00:57
Estimated running time left :   0:00:26

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83931 +/- 0.00240  [0.83461  0.84401]
k-eff (implicit)  = 0.83830 +/- 0.00104  [0.83626  0.84034]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   47 / 100  Source neutrons :  4952

Running time :                  0:00:31
Estimated running time :        0:00:57
Estimated running time left :   0:00:25

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83930 +/- 0.00235  [0.83470  0.84390]
k-eff (implicit)  = 0.83833 +/- 0.00102  [0.83634  0.84033]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   48 / 100  Source neutrons :  5081

Running time :                  0:00:31
Estimated running time :        0:00:57
Estimated running time left :   0:00:25

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83958 +/- 0.00231  [0.83504  0.84411]
k-eff (implicit)  = 0.83828 +/- 0.00100  [0.83632  0.84023]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   49 / 100  Source neutrons :  4830

Running time :                  0:00:32
Estimated running time :        0:00:56
Estimated running time left :   0:00:24

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83925 +/- 0.00229  [0.83476  0.84374]
k-eff (implicit)  = 0.83831 +/- 0.00098  [0.83640  0.84023]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   50 / 100  Source neutrons :  5171

Running time :                  0:00:32
Estimated running time :        0:00:56
Estimated running time left :   0:00:24

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83950 +/- 0.00226  [0.83507  0.84392]
k-eff (implicit)  = 0.83848 +/- 0.00097  [0.83657  0.84038]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   51 / 100  Source neutrons :  4947

Running time :                  0:00:33
Estimated running time :        0:00:56
Estimated running time left :   0:00:23

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83956 +/- 0.00221  [0.83522  0.84390]
k-eff (implicit)  = 0.83843 +/- 0.00095  [0.83656  0.84030]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   52 / 100  Source neutrons :  4832

Running time :                  0:00:33
Estimated running time :        0:00:56
Estimated running time left :   0:00:23

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83907 +/- 0.00222  [0.83472  0.84343]
k-eff (implicit)  = 0.83841 +/- 0.00094  [0.83658  0.84025]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   53 / 100  Source neutrons :  5104

Running time :                  0:00:34
Estimated running time :        0:00:56
Estimated running time left :   0:00:22

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83893 +/- 0.00219  [0.83464  0.84321]
k-eff (implicit)  = 0.83842 +/- 0.00092  [0.83662  0.84022]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   54 / 100  Source neutrons :  4947

Running time :                  0:00:34
Estimated running time :        0:00:56
Estimated running time left :   0:00:22

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83862 +/- 0.00217  [0.83437  0.84287]
k-eff (implicit)  = 0.83824 +/- 0.00092  [0.83644  0.84004]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   55 / 100  Source neutrons :  5038

Running time :                  0:00:35
Estimated running time :        0:00:56
Estimated running time left :   0:00:21

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83844 +/- 0.00213  [0.83426  0.84263]
k-eff (implicit)  = 0.83817 +/- 0.00091  [0.83640  0.83995]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   56 / 100  Source neutrons :  5084

Running time :                  0:00:35
Estimated running time :        0:00:56
Estimated running time left :   0:00:21

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83852 +/- 0.00210  [0.83440  0.84263]
k-eff (implicit)  = 0.83809 +/- 0.00089  [0.83634  0.83984]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   57 / 100  Source neutrons :  4909

Running time :                  0:00:36
Estimated running time :        0:00:56
Estimated running time left :   0:00:20

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83832 +/- 0.00207  [0.83426  0.84238]
k-eff (implicit)  = 0.83820 +/- 0.00088  [0.83647  0.83993]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   58 / 100  Source neutrons :  4951

Running time :                  0:00:36
Estimated running time :        0:00:56
Estimated running time left :   0:00:20

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83799 +/- 0.00206  [0.83395  0.84203]
k-eff (implicit)  = 0.83813 +/- 0.00087  [0.83642  0.83984]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   59 / 100  Source neutrons :  5098

Running time :                  0:00:37
Estimated running time :        0:00:56
Estimated running time left :   0:00:19

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83794 +/- 0.00203  [0.83397  0.84191]
k-eff (implicit)  = 0.83818 +/- 0.00086  [0.83650  0.83986]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   60 / 100  Source neutrons :  4836

Running time :                  0:00:37
Estimated running time :        0:00:56
Estimated running time left :   0:00:19

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83744 +/- 0.00205  [0.83341  0.84147]
k-eff (implicit)  = 0.83792 +/- 0.00088  [0.83619  0.83965]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   61 / 100  Source neutrons :  5255

Running time :                  0:00:38
Estimated running time :        0:00:56
Estimated running time left :   0:00:18

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83763 +/- 0.00203  [0.83365  0.84161]
k-eff (implicit)  = 0.83793 +/- 0.00087  [0.83623  0.83963]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   62 / 100  Source neutrons :  4846

Running time :                  0:00:38
Estimated running time :        0:00:56
Estimated running time left :   0:00:18

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83739 +/- 0.00201  [0.83345  0.84133]
k-eff (implicit)  = 0.83783 +/- 0.00086  [0.83614  0.83951]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   63 / 100  Source neutrons :  5153

Running time :                  0:00:39
Estimated running time :        0:00:56
Estimated running time left :   0:00:17

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83756 +/- 0.00199  [0.83367  0.84145]
k-eff (implicit)  = 0.83787 +/- 0.00085  [0.83621  0.83953]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   64 / 100  Source neutrons :  4940

Running time :                  0:00:39
Estimated running time :        0:00:56
Estimated running time left :   0:00:17

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83757 +/- 0.00195  [0.83374  0.84140]
k-eff (implicit)  = 0.83778 +/- 0.00084  [0.83614  0.83942]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   65 / 100  Source neutrons :  5114

Running time :                  0:00:40
Estimated running time :        0:00:56
Estimated running time left :   0:00:16

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83787 +/- 0.00195  [0.83405  0.84168]
k-eff (implicit)  = 0.83770 +/- 0.00083  [0.83607  0.83932]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   66 / 100  Source neutrons :  4874

Running time :                  0:00:40
Estimated running time :        0:00:56
Estimated running time left :   0:00:16

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83783 +/- 0.00192  [0.83407  0.84159]
k-eff (implicit)  = 0.83762 +/- 0.00082  [0.83601  0.83923]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   67 / 100  Source neutrons :  5093

Running time :                  0:00:41
Estimated running time :        0:00:57
Estimated running time left :   0:00:15

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83802 +/- 0.00190  [0.83430  0.84175]
k-eff (implicit)  = 0.83742 +/- 0.00083  [0.83579  0.83906]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   68 / 100  Source neutrons :  4720

Running time :                  0:00:41
Estimated running time :        0:00:57
Estimated running time left :   0:00:15

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83751 +/- 0.00194  [0.83371  0.84131]
k-eff (implicit)  = 0.83748 +/- 0.00082  [0.83587  0.83909]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   69 / 100  Source neutrons :  5186

Running time :                  0:00:42
Estimated running time :        0:00:57
Estimated running time left :   0:00:15

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83745 +/- 0.00191  [0.83370  0.84120]
k-eff (implicit)  = 0.83738 +/- 0.00082  [0.83578  0.83898]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   70 / 100  Source neutrons :  4945

Running time :                  0:00:42
Estimated running time :        0:00:57
Estimated running time left :   0:00:14

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83726 +/- 0.00189  [0.83355  0.84097]
k-eff (implicit)  = 0.83733 +/- 0.00081  [0.83575  0.83891]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   71 / 100  Source neutrons :  5134

Running time :                  0:00:43
Estimated running time :        0:00:57
Estimated running time left :   0:00:14

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83738 +/- 0.00187  [0.83372  0.84105]
k-eff (implicit)  = 0.83724 +/- 0.00080  [0.83567  0.83880]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   72 / 100  Source neutrons :  4762

Running time :                  0:00:43
Estimated running time :        0:00:57
Estimated running time left :   0:00:13

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83694 +/- 0.00190  [0.83323  0.84066]
k-eff (implicit)  = 0.83734 +/- 0.00080  [0.83578  0.83890]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   73 / 100  Source neutrons :  5208

Running time :                  0:00:44
Estimated running time :        0:00:57
Estimated running time left :   0:00:13

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83698 +/- 0.00187  [0.83331  0.84064]
k-eff (implicit)  = 0.83739 +/- 0.00079  [0.83585  0.83893]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   74 / 100  Source neutrons :  5074

Running time :                  0:00:44
Estimated running time :        0:00:57
Estimated running time left :   0:00:12

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83718 +/- 0.00186  [0.83354  0.84081]
k-eff (implicit)  = 0.83727 +/- 0.00078  [0.83573  0.83880]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   75 / 100  Source neutrons :  4814

Running time :                  0:00:45
Estimated running time :        0:00:57
Estimated running time left :   0:00:12

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83695 +/- 0.00185  [0.83333  0.84057]
k-eff (implicit)  = 0.83721 +/- 0.00078  [0.83569  0.83873]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   76 / 100  Source neutrons :  5117

Running time :                  0:00:45
Estimated running time :        0:00:57
Estimated running time left :   0:00:11

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83698 +/- 0.00182  [0.83341  0.84055]
k-eff (implicit)  = 0.83719 +/- 0.00077  [0.83568  0.83869]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   77 / 100  Source neutrons :  4981

Running time :                  0:00:46
Estimated running time :        0:00:57
Estimated running time left :   0:00:11

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83697 +/- 0.00180  [0.83345  0.84049]
k-eff (implicit)  = 0.83715 +/- 0.00076  [0.83566  0.83863]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   78 / 100  Source neutrons :  4892

Running time :                  0:00:46
Estimated running time :        0:00:57
Estimated running time left :   0:00:10

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83672 +/- 0.00179  [0.83322  0.84023]
k-eff (implicit)  = 0.83720 +/- 0.00075  [0.83573  0.83867]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   79 / 100  Source neutrons :  5267

Running time :                  0:00:47
Estimated running time :        0:00:57
Estimated running time left :   0:00:10

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83704 +/- 0.00180  [0.83352  0.84056]
k-eff (implicit)  = 0.83719 +/- 0.00074  [0.83574  0.83864]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   80 / 100  Source neutrons :  4790

Running time :                  0:00:47
Estimated running time :        0:00:57
Estimated running time left :   0:00:09

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83690 +/- 0.00178  [0.83341  0.84038]
k-eff (implicit)  = 0.83720 +/- 0.00073  [0.83577  0.83863]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   81 / 100  Source neutrons :  4876

Running time :                  0:00:48
Estimated running time :        0:00:57
Estimated running time left :   0:00:09

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83650 +/- 0.00180  [0.83297  0.84003]
k-eff (implicit)  = 0.83721 +/- 0.00072  [0.83580  0.83863]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   82 / 100  Source neutrons :  5004

Running time :                  0:00:48
Estimated running time :        0:00:57
Estimated running time left :   0:00:08

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83613 +/- 0.00182  [0.83256  0.83969]
k-eff (implicit)  = 0.83721 +/- 0.00071  [0.83581  0.83860]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   83 / 100  Source neutrons :  5153

Running time :                  0:00:49
Estimated running time :        0:00:57
Estimated running time left :   0:00:08

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83606 +/- 0.00180  [0.83254  0.83958]
k-eff (implicit)  = 0.83719 +/- 0.00070  [0.83581  0.83857]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   84 / 100  Source neutrons :  5087

Running time :                  0:00:49
Estimated running time :        0:00:57
Estimated running time left :   0:00:07

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83616 +/- 0.00178  [0.83268  0.83965]
k-eff (implicit)  = 0.83711 +/- 0.00070  [0.83574  0.83849]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   85 / 100  Source neutrons :  4976

Running time :                  0:00:50
Estimated running time :        0:00:57
Estimated running time left :   0:00:07

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83621 +/- 0.00176  [0.83277  0.83966]
k-eff (implicit)  = 0.83705 +/- 0.00069  [0.83568  0.83841]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   86 / 100  Source neutrons :  5022

Running time :                  0:00:50
Estimated running time :        0:00:57
Estimated running time left :   0:00:06

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83631 +/- 0.00174  [0.83290  0.83972]
k-eff (implicit)  = 0.83700 +/- 0.00069  [0.83566  0.83835]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   87 / 100  Source neutrons :  4868

Running time :                  0:00:50
Estimated running time :        0:00:57
Estimated running time left :   0:00:06

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83615 +/- 0.00173  [0.83276  0.83953]
k-eff (implicit)  = 0.83710 +/- 0.00069  [0.83575  0.83844]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   88 / 100  Source neutrons :  5084

Running time :                  0:00:51
Estimated running time :        0:00:57
Estimated running time left :   0:00:05

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83614 +/- 0.00171  [0.83280  0.83949]
k-eff (implicit)  = 0.83703 +/- 0.00068  [0.83569  0.83837]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   89 / 100  Source neutrons :  5052

Running time :                  0:00:51
Estimated running time :        0:00:57
Estimated running time left :   0:00:05

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83624 +/- 0.00169  [0.83292  0.83956]
k-eff (implicit)  = 0.83708 +/- 0.00068  [0.83576  0.83841]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   90 / 100  Source neutrons :  4906

Running time :                  0:00:52
Estimated running time :        0:00:57
Estimated running time left :   0:00:04

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83616 +/- 0.00167  [0.83287  0.83944]
k-eff (implicit)  = 0.83696 +/- 0.00068  [0.83563  0.83829]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   91 / 100  Source neutrons :  5034

Running time :                  0:00:52
Estimated running time :        0:00:57
Estimated running time left :   0:00:04

Estimated relative CPU usage :   100.1%

k-eff (analog)    = 0.83614 +/- 0.00166  [0.83289  0.83938]
k-eff (implicit)  = 0.83691 +/- 0.00067  [0.83559  0.83823]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   92 / 100  Source neutrons :  5017

Running time :                  0:00:53
Estimated running time :        0:00:57
Estimated running time left :   0:00:03

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83615 +/- 0.00164  [0.83294  0.83936]
k-eff (implicit)  = 0.83703 +/- 0.00068  [0.83570  0.83835]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   93 / 100  Source neutrons :  5118

Running time :                  0:00:54
Estimated running time :        0:00:57
Estimated running time left :   0:00:03

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83637 +/- 0.00164  [0.83317  0.83958]
k-eff (implicit)  = 0.83698 +/- 0.00067  [0.83566  0.83829]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   94 / 100  Source neutrons :  4978

Running time :                  0:00:54
Estimated running time :        0:00:57
Estimated running time left :   0:00:02

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83655 +/- 0.00163  [0.83336  0.83974]
k-eff (implicit)  = 0.83702 +/- 0.00066  [0.83572  0.83832]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   95 / 100  Source neutrons :  4931

Running time :                  0:00:55
Estimated running time :        0:00:57
Estimated running time left :   0:00:02

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83660 +/- 0.00161  [0.83344  0.83976]
k-eff (implicit)  = 0.83698 +/- 0.00066  [0.83569  0.83827]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   96 / 100  Source neutrons :  4796

Running time :                  0:00:55
Estimated running time :        0:00:57
Estimated running time left :   0:00:01

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83630 +/- 0.00162  [0.83311  0.83948]
k-eff (implicit)  = 0.83709 +/- 0.00066  [0.83579  0.83838]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   97 / 100  Source neutrons :  5254

Running time :                  0:00:55
Estimated running time :        0:00:57
Estimated running time left :   0:00:01

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83642 +/- 0.00161  [0.83326  0.83958]
k-eff (implicit)  = 0.83700 +/- 0.00066  [0.83570  0.83829]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   98 / 100  Source neutrons :  5044

Running time :                  0:00:56
Estimated running time :        0:00:57
Estimated running time left :   0:00:00

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83661 +/- 0.00161  [0.83346  0.83977]
k-eff (implicit)  = 0.83691 +/- 0.00066  [0.83562  0.83820]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle   99 / 100  Source neutrons :  4931

Running time :                  0:00:56
Estimated running time :        0:00:57
Estimated running time left :   0:00:00

Estimated relative CPU usage :    99.9%

k-eff (analog)    = 0.83669 +/- 0.00159  [0.83356  0.83981]
k-eff (implicit)  = 0.83689 +/- 0.00065  [0.83561  0.83817]

(O4) (OMP=1) 
------------------------------------------------------------
------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle  100 / 100  Source neutrons :  4981

Running time :                  0:00:57
Estimated running time :        0:00:57
Estimated running time left :   0:00:00

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83673 +/- 0.00158  [0.83363  0.83982]
k-eff (implicit)  = 0.83705 +/- 0.00067  [0.83575  0.83836]

(O4) (OMP=1) 
------------------------------------------------------------

Transport cycle completed in 56.3 seconds.

The output of a simple Serpent simulation can be divided to the pre-processing part and the neutron transport part. The pre-processing part consists of reading the input-files and processing the material, geometry and cross section data, whereas the neutron transport part consists of first executing the inactive cycles, followed by the execution of the active cycles.

The results are only collected during the active cycles. The inactive cycles are used to allow the fission source to converge from the initial guess to its fundamental mode before the collection of the results is begun. If too few inactive cycles are used, the collected results do not represent the fundamental mode and will be incorrect. One of the traditional methods for estimating the required number of inactive cycles is to monitor the Shannon entropy of the fission source as a function of the cycle number (see set his).

Running the input will also produce multiple output files, the full description of which can be found here. The main output file infinite_res.m contains many result variables calculated from the simulation and can be executed with MATLAB or OCTAVE to automatically bring the variables in as workspace variables.

Finding the critical uranium enrichment

For the next part of the tutorial you can try to find out the critical enrichment for the fuel material. Let's look at the fuel material definition a bit closer:

% --- Fuel material (4.0 wt-% enriched uranium dioxide), density 10.1 g/cm3

mat fuel     -10.1
92235.03c    -0.04 
92238.03c    -0.96

The first line of the material definition contains the command word mat which tells Serpent that a material definition will follow. The name of the material is set to fuel and the density of the material is set to -10.1, where the negative number tells Serpent that it should be interpreted as mass density (a positive number would indicate atomic density). The unit of mass density (see the list of units) used in Serpent is g/cm3. The initial material definition line is followed by the material composition:

92235.03c    -0.04 
92238.03c    -0.96

Here the value on the left is the nuclide id (which must correspond to an entry in the cross section directory file) and the value on the right is its mass fraction (negative number) or atomic fraction (positive number) in the composition. The nuclide ids consist of three parts:

92235.03c    -0.04 
92238.03c    -0.96
  1. The first one or two numbers are the atomic number of the nuclide.
  2. The following three numbers give the mass number of the nuclide.
  3. The last three characters after a period/dot give the library identifier of the nuclide. The library identifier typically represents the temperature of the nuclide (and in some cases the cross section library).

In our case, the atomic number of both nuclides in the composition is 92 indicating that the nuclides are uranium. The mass numbers of the two nuclides are 235 and 238 further identifying the nuclides as 235U and 238U. The library identifier 03c indicates that those variants of the 235U and 238U cross section libraries that are in the temperature of 300 K should be used.

The mass fractions given in the material definition mean that the material consists of 0.04 parts (in mass) of 235U and 0.96 parts (in mass) of 238U. This equals an enrichment of 4.0 wt.-%.

By changing the mass fractions given for the two nuclides, you can try to find a material composition that results in a multiplication factor of approximately 1.0. The statistical estimate for the multiplication factor along with its 2-sigma confidence interval is printed out by Serpent during the simulation:

------------------------------------------------------------

Serpent 2.1.29 -- Static criticality source simulation

Input file: "infinite" 

Active cycle  100 / 100  Source neutrons :  4981

Running time :                  0:00:57
Estimated running time :        0:00:57
Estimated running time left :   0:00:00

Estimated relative CPU usage :   100.0%

k-eff (analog)    = 0.83673 +/- 0.00158  [0.83363  0.83982]
k-eff (implicit)  = 0.83705 +/- 0.00067  [0.83575  0.83836]

(O4) (OMP=1) 
------------------------------------------------------------

Here, k-eff (analog) and k-eff (implicit) are two separate statistical estimators for the multiplication factor of the system that can be used to estimate the criticality of the system. As the system is currently subcritical (k-eff is smaller than 1.0), it would be a good idea to increase the 235U content slightly and re-run the calculation.

By tuning the material composition, you should be able to obtain a more or less critical system.

Calculating the flux energy spectrum

In order to calculate the flux energy spectrum in the critical system we will define a detector in the input. Detectors are described in Section 7 of the Serpent manual and can be used to calculate neutron or photon flux, reaction rate, energy spectrum, heat deposition etc. at various parts of the geometry. The short syntax for detector input can be found in the input syntax manual.

Here we will set up a simple detector

% --- Detector for tallying the flux energy spectrum
%     The energy grid used for tallying will be defined later

det EnergyDetector de MyEnergyGrid

The detector has the name EnergyDetector and the additional option de tells Serpent that we want to use an energy grid with the name MyEnergyGrid to tally the energy spectrum of the neutron flux.

We'll still need to define the energy grid:

% --- Define the energy grid to be used with the detector
%     Grid type 3 (bins have uniform lethargy width)
%     500 bins between 1e-11 MeV and 2e1 MeV.

ene MyEnergyGrid 3 500 1e-11 2e1

The energy grid has 500 bins between the energies of 1e-11 MeV and 2e1 MeV. Since the energy grid type is set to 3, Serpent will automatically divide the energy interval into the requested number of bins equally wide in lethargy.

With the detector and energy grid definitions added to the input file, you can re-run the calculation to obtain the detector output file infinite_det0.m. The structure of the detector output file is described in Section 7.2 of the Serpent manual.

You can use the OCTAVE script below to plot the flux-spectrum.

OCTAVE script for plotting flux spectrum

#########################################
## Initial checking and pre-processing ##
#########################################

## Check that the detector file exists

if (exist("./infinite_det0.m", "file") != 2)
  disp("Could not find infinite_det0.m from current folder! Cannot do analysis.")
  exit()
endif

## Run the detector output file to bring the results to workspace

run infinite_det0.m;

## Check that the detector output exist

if (exist("DETEnergyDetector", "var") != 1)
  disp("Could not find results for EnergyDetector from the detector\
 file (maybe misspelled detector name?). Cannot do analysis.")
  exit()
endif

#####################################
## Plot the energy-integrated flux ##
#####################################

## Scale the energy integrated flux to a maximum of 1.0

DETEnergyDetector(:,11) = DETEnergyDetector(:,11)/max(DETEnergyDetector(:,11));

## Plot

figure('visible','off');

errorbar(DETEnergyDetectorE(:,3), DETEnergyDetector(:,11), 
         2*DETEnergyDetector(:,11).*DETEnergyDetector(:,12),'k.');

## Set axes

set(gca,'XScale','log');
set(gca,'YScale','log');
set(gca,'XTick',[1e-12,1e-10,1e-8,1e-6,1e-4,1e-2,1e0,1e2]);
set(gca,'FontSize',16);

## Make the plot a bit nicer

xlabel('Energy (MeV)')
ylabel('Energy integrated neutron flux (a.u.)')
grid on
grid minor off
box on

## Save the figure

print -dpng FluxEInt.png;

## Save the figure with linear y-axis

set(gca,'YScale','linear');
ylim([0,1]);

print -dpng FluxEIntLinY.png;

Copy and paste the contents of the OCTAVE script to a file (you can name the file, e.g. analyze.m) in the same directory as infinite_det0.m and run it with OCTAVE (e.g. octave analyze.m). This should produce figure files FluxEInt.png and FluxEIntLinY.png to the same directory.

The figures should look more or less like these:

Neutron flux of the infinite critical uranium system integrated to 500 energy bins of equal logarithmic width between 1e-11 MeV and 20 MeV. Logarithmic y-axis. Neutron flux of the infinite critical uranium system integrated to 500 energy bins of equal logarithmic width between 1e-11 MeV and 20 MeV. Linear y-axis.

We can see that the most of the neutron flux lies between 1e-2 and 1e1 MeV, which means that the system has a very fast neutron spectrum. As there are no light elements to work as neutron moderators, this is no surprise.

Testing the effect of added moderation

We can test how the addition of some light elements, e.g. hydrogen will affect the multiplication factor and flux spectrum of the system.

Starting from the (more or less) critical material definition

% --- Fuel material (5.76 wt-% enriched uranium), density 10.1 g/cm3

mat fuel     -10.1
92235.03c    -0.0576 
92238.03c    -0.9424

we can add some hydrogen-1: The atomic number of hydrogen-1 is 1 and the mass number is also 1, which means that the basic part of the nuclide id will be 1001. We'll use the same library identifier as for the uranium, i.e. 03c:

% --- Fuel material (5.76 wt-% enriched uranium + some hydrogen), density 10.1 g/cm3
%     One part (in mass) of uranium, 0.005 parts (in mass) of hydrogen

mat fuel     -10.1
92235.03c    -0.0576 
92238.03c    -0.9424
 1001.03c    -0.005

Here we have added 0.005 parts (in mass) of hydrogen-1 to our pre-existing 1.0 parts (in mass) of uranium. You may notice that the mass fractions now sum up to more than 1.0. In such situations Serpent will automatically normalize the mass-fractions so that they add up to 1.0.

Now you can run the simulation again.

You should notice that the multiplication factor is much higher this time, indicating that the addition of moderating material to the system increased the reactivity of the system.

By running the OCTAVE script again, you can plot the flux-spectrum from the moderated system to obtain something like this:

Neutron flux of the infinite moderated uranium system integrated to 500 energy bins of equal logarithmic width between 1e-11 MeV and 20 MeV. Logarithmic y-axis. Neutron flux of the infinite moderated uranium system integrated to 500 energy bins of equal logarithmic width between 1e-11 MeV and 20 MeV. Linear y-axis.

Comparing these plots to the previous ones shows that the moderated system is more thermal, i.e. has higher neutron flux at the thermal energies than the unmoderated one.

Additional ideas for testing and tinkering

  • Test the effect of unresolved resonance probability table sampling on the multiplication factor and flux spectrum of the critical fast system (set ures). The probability table sampling should be always set on for the simulation of fast systems. Do you see an effect on the running time?
  • Test changing the limiting surface s1 from type inf to one of the other surface types. What is the multiplication factor of a 10x10x10 cm cube (surface type cuboid)? How large does the cube have to be to be considered infinite (i.e. to get the same k-eff as in the infinite system)?
  • Modify the input so that you have a 200x200x200 cm cube of uranium surrounded by a 10 cm cubic layer of heavy water. You'll need to add a second cuboid surface and one more cell definition. You can use the material definition below for the heavy water. What is the multiplication factor? How thick does the heavy water layer need to be for the system to be critical?
% --- Heavy water (density 1.11 g/cm3)
%     2 parts (atomic) of hydrogen-2, 1 parts (atomic) of oxygen-16
%     Hydrogen 2 is flagged as a bound scatterer with the "moder"-card

mat heavywater -1.11 moder MyThermLib 1002
 1002.03c       2
 8016.03c       1

% --- Define thermal scattering libraries associated with hydrogen-2

therm MyThermLib hwj3.00t

2D Pin-cell model

Overview

The second model we shall use is a 2 dimensional pin-cell model (i.e. an infinite square lattice of fuel pins). The geometry is infinite both axially and radially.

We'll also use the geometry and mesh-plotter capabilities in Serpent.

Input

Colors in input correspond to:

  • Comments
  • Control words
  • Name definitions
  • Name references

Input for 2D pin-cell geometry

% --- Simple 2D PWR pin-cell geometry for Serpent tutorial

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

% --- Fuel material (3.0 wt-% enriched uranium dioxide), density 10.1 g/cm3

mat fuel     -10.1
92235.03c    -0.02644492
92238.03c    -0.85505247
 8016.03c    -0.11850261

% --- Cladding material for fuel rod
%     (100 % natural zirconium)

mat clad     -6.55
40000.03c    -1.0

% --- Water at 1.0 g/cm3
%     Defined using atomic fractions for the composition. 
%     Hydrogen is flagged as a bound scatterer with the "moder"-card

mat water    -1.0 moder MyThermLib 1001
 1001.03c     2.0
 8016.03c     1.0

% --- Define thermal scattering libraries associated with hydrogen in light water

therm MyThermLib lwj3.00t

/************************
 * Geometry definitions *
 ************************/

% --- Fuel pin structure

pin p1
fuel    0.4025
clad    0.4750
water

% --- Square surface with 1.5 cm side centered at (x,y) = (0,0)

surf s1 sqc 0.0 0.0 0.75

% --- Cell c1 belongs to the base universe 0, is filled with the pin p1
%     and covers everything inside surface s1

cell c1 0 fill p1   -s1

% --- Cell c2 belongs to the base universe 0, is defined as an "outside" cell
%     and covers everything inside surface s1

cell c2 0 outside    s1

/******************
 * Run parameters *
 ******************/

% --- Neutron population

set pop 5000 100 20

% --- Boundary condition (1 = black, 2 = reflective, 3 = periodic)

set bc 2

% --- Geometry plots
%     First two plots are perpendicular to z-axis i.e. xy-plots (3)

% --- First plot is 200 by 200 pixels and covers the whole geometry: -0.75 < (x,y) < 0.75

plot 3  200  200

% --- Second plot is 1000 by 1000 pixels, from axial height z = 0.0 
%     and covers more than the whole geometry: -2.25 < (x,y) < 2.25

plot 3 1000 1000 0.0 -2.25 2.25 -2.25 2.25

% --- The third plot is perpendicular to y-axis (2) i.e. an xz-plot

plot 2  200  200

% --- 200 by 200 pixel meshplot that covers the whole geometry: -0.75 < (x,y) < 0.75

mesh 3  200  200

Plotting the input

Copy and paste the input to a file named pin on your computer.

Before running the input, it is typically a good idea to plot the geometry to verify that it has been defined correctly. The basics of geometry, track and mesh plotting are explained on a separate wiki page.

It is possible to execute only the geometry plotter, without running the neutron transport by using the command line argument -plot

sss2 -plot pin

This will produce three plot files pin_geom1.png, pin_geom2.png, pin_geom3.png, which should look like the ones below:

xy-plot of the tutorial pin-cell geometry. xy-plot of the tutorial pin-cell geometry (3 pin pitches). xz-plot of the tutorial pin-cell geometry.

You will probably notice that the colors in your geometry plots are a bit different from the ones shown above. If the user does not define a color for a material, Serpent will use a random color. Let's specify the colors for our materials using the rgb card:

% --- Fuel material (3.0 wt-% enriched uranium dioxide), density 10.1 g/cm3</span>

mat fuel     -10.1 rgb 240 240 100
92235.03c    -0.02644492
92238.03c    -0.85505247
 8016.03c    -0.11850261

% --- Cladding material for fuel rod
%     (100 % natural zirconium)

mat clad     -6.55 rgb 150 150 150
40000.03c    -1.0

% --- Water at 1.0 g/cm3
%     Defined using atomic fractions for the composition. 
%     Hydrogen is flagged as a bound scatterer with the "moder"-card

mat water    -1.0 moder MyThermLib 1001 rgb 200 200 255
 1001.03c     2.0
 8016.03c     1.0

The rgb card is followed by three integer values between 0-255 for red, green and blue respectively. The ordering of additional cards in the material definition (e.g. the moder and the rgb cards) is interchangeable.

Re-plotting the figures with the material colors specified, should produce the same plots as previously, but with colors as below:

xy-plot of the tutorial pin-cell geometry. The material colors are now defined using the rgb-card for material definitions.

It is often a good idea to define easily distinguishable colors for each material so that they can be identified from the geometry plots. This makes it easier to spot cases, where the wrong material is used in a wrong place. Certain RGB-colors are used by Serpent to indicate specific problems with the geometry:

RGB value Color Description
(0, 0, 0) COLOR Outside cell or void-material.
(0, 255, 0) COLOR No cell found at coordinates.
(255, 0, 0) COLOR Overlap of multiple cells found at coordinates.
(255, 0, 255) COLOR Undefined material density factor at coordinates.

Running the input

Simply run the input from terminal, by being in the same directory as the input-file and executing

sss2 [-omp N] pin

the simulation should, again, produce multiple output files. This time a mesh-plot (pin_mesh1.png) is also produced:

xy-meshplot of the tutorial pin-cell geometry.

Additional ideas for testing and tinkering

2D Assembly model

Overview

Basics

Testing and tinkering