Editing Input syntax manual (section)

=== pbed (explicit stochastic (pebble bed) geometry definition)<span id="pbed"></span> ===

 '''pbed''' ''UNI<sub>0</sub>'' ''UNI<sub>bg</sub>'' ''FILE'' [ ''OPT'' ] 
Defines a stochastic particle / pebble-bed geometry. Input values:

{|
| <tt>''UNI<sub>0</sub>''</tt> 
| : universe name for the dispersed medium
|-
| <tt>''UNI<sub>bg</sub>''</tt>
| : background universe, i.e. universe filling the space between particles / pebbles
|-
| <tt>''FILE''</tt>
|: input file containing the particle/pebble data
|-
| <tt>''OPT''</tt>
|: additional options
|}

The <u>syntax of the file</u> containing the particle/pebble data is: 

::{| class="toccolours" style="text-align: left;"
| ''X<sub>1</sub>'' ''Y<sub>1</sub>'' ''Z<sub>1</sub>'' ''R<sub>1</sub>'' ''UNI<sub>1</sub>''
|-
| ''X<sub>2</sub>'' ''Y<sub>2</sub>'' ''Z<sub>2</sub>'' ''R<sub>2</sub>'' ''UNI<sub>2</sub>''
|-
| ...
|-
|}

where:
{|
|<tt>''X<sub>n</sub>'', ''Y<sub>n</sub>'', ''Z<sub>n</sub>''</tt>
|: are the coordinates [in cm]
|-
|<tt>''R<sub>n</sub>''</tt>
|: is the radius [in cm]
|-
|<tt>''UNI<sub>n</sub>''</tt>
|: is the universe
|}

The supported <u>additional options</u> are:
::{| class="wikitable" style="text-align: left;"
! Option
! Description
|-
| <tt>pow</tt>
| power distribution
|-
|}

<u>Notes:</u>

*Creates a universe (<tt>''UNI<sub>0</sub>''</tt>), which is filled with spherical sub-universes for which the coordinates are read from a separate file.
*The coordinates can be defined manually, or using the [[Installing_and_running_Serpent#Running Serpent|<tt>''-disperse''</tt>]] command line option which launches the particle disperser routine.
*Can be used for modelling stochastic particle / pebble-bed geometries in multiple levels.
*If the "<tt>pow</tt>" (power distribution) option is set, the pebble/particle-wise distribution is written in file <tt>[''FILE'']_pow[bu].m</tt>, where "<tt>bu</tt>" is the burnup step, from version 2.2.1 and on (in previous versions, <tt>[''FILE''].out</tt>).
*See also [[Collection_of_example_input_files#Simple_burnup_examples|HTGR geometry examples]].