Running MCNP and ADVANTG with Cyclone

Cyclone Process Flow with ADVANTG

The Cyclone workflow with ADVANTG follows the same sequence as the standard MCNP-only workflow, with an additional step that generates and runs an ADVANTG input file prior to MCNP execution. The resulting weight window file is validated and placed in the same directory as the MCNP input file. During this process, the MCNP input is automatically updated to include source biasing and weight window parameters. After ADVANTG completes, any temporary files and folders are deleted, and execution continues with the MCNP run. This workflow applies to both single MCNP cases and parameterised runs (see Figure 12).

ADVANTG Options

ADVANTG has many execution options and parameters which can be specified in the main Cyclone interface. For a full description of each option, refer to the ADVANTG manual [3]. Some commonly used options are:

• Version – Choose between 3.0 and 3.2. This affects which options are available, so the user should ensure they select the version that matches their installation.

• Variance Reduction Method – Select from cadis, fwcadis or dx.

• ADVANTG Target Tallies – Leave blank to target all tallies in the MCNP input or specify a list to limit the target tallies.

Mesh Specification

The only ADVANTG option that is not available through the main Cyclone interface is the ability to define a MESH. Instead, this must be specified in the MCNP input file. For example:

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1c CYCLONE ADVANTG MESH START
2c XMESH -788 -588 -381 -164 140 178 338 528 588 788 END
3c XINT 2 25 2 25 2 25 2 25 2 END
4c YMESH -800 -298 -213 523 600 800 END
5c YINT 2 25 2 25 2 END
6c ZMESH -50 350 END
7c ZINT 50 END
8c CYCLONE ADVANTG MESH FINISH

To ensure correct operation with MCNP, each line must be commented out using the standard MCNP comment character c. This prevents the Cyclone-specific data from being interpreted by MCNP. Each block must begin and end with clearly defined markers, as shown above.

Cyclone searches for the following keywords in the input file[^1]:

• CYCLONE ADVANTG MESH START

• CYCLONE ADVANTG MESH FINISH

• XMESH

• XINT

• YMESH

• YINT

• ZMESH

• ZINT

• END

Defining the mesh in the MCNP input also allows parameters to be used where needed.

Figure 11: ADVANTG options Figure 12: Cyclone MCNP and ADVANTG process flow