Generic Simulation Parameters

Simulation parameters are specific to the main configuration of the simulation, unlike source, tally, geometry, or material configurations. This section describes the available parameters for the pen_main program, which control the overall behavior and execution of the simulation. This parameters can be found in the Simulation properties world tag.

Simulation properties tag

Dumps and Results Control

PenRed provides the capability to dump the current state of the entire simulation. This dump can be used to:

  • Resume a simulation after computer crash.
  • Store the final results in binary format.
  • Combine the results of simulations with the same configuration.

To configure this feature, the following parameters are available:

Dumps

This parameters group handles the simulation checkpointing. By default, both, writing and reading dump files is disabled.

  • Write interval
    Specifies the time interval, in seconds, between successive dumps.

  • Write File
    Specifies the filename used to save the dumps. Each thread will automatically append the thN prefix to the filename, where N is the thread number.

  • Read File
    Expects a string with the name of a dump file to resume a previous simulation.
    Note: If multiple threads are used, the simulation must be resumed with the same number of threads as the original simulation. Each thread will attempt to read a file with the specified name prefixed by thN, where N is the thread number. For example, if the filename is dump.dat, the file for thread number 2 must be named th2dump.dat.

Results

The Results group controls how the simulation results are saved.

  • Prefix
    This parameter allows the user to specify a prefix for the ASCII results produced by every tally. The prefix will be appended to the usual results filenames.
    Note: To specify an output directory, a trailing slash is required:

    • Use / for Linux (e.g., output/).
    • Use \ for Windows (e.g., output\).
      The specified directory must exist before the simulation starts.

  • Final Dump
    If enabled, forces a dump in each thread at the end of the simulation.
    Default: Disabled.

  • ASCII Results
    Enables or disables result reports in ASCII format. If disabled, the result reports will be written to a dump file named results.dump. Additionally, no partial results will be printed during the simulation.
    Default: Enabled.

  • ASCII Partial Results
    If ASCII Results is enabled, this boolean value can enable or disable the ASCII printing of partial results.
    Default: Disabled.

Threading

The following parameters control the multi-threading capabilities of the simulation:

  • Threads Selection
    Controls how the number of threads are selected:
    • Auto: The number of threads is authomatically set according to the number of virtual cores.
    • Manual: The number of threads is specified by the user.
  • Threads
    An integer value that specifies the number of threads to be used. It is only available if the thread selection is set to Manual.
  • Seed Pair
    Specify the seed pair number used to initialize the random number generator.

The number of histories to simulate on each source will be distributed among all specified threads.

Time Limit

If enabled the user can specify the maximum duration, in seconds, that the simulation is allowed to run.