Visual Editor Banner
About Us Training Software Support
Main Page Visual Editor Training The Visual Editor Get the Visual Editor
Company Info Penelope/PenGUIn Workshops Nucwiz Help, Support, Known Bugs
Email Randy Schwarz MCNP6 Intermed. Workshops Penelope/PenGUIn Free Downloads
Vised Gallery Onsite Training Other Software C++ Tips and Tricks
Vised Video Demos. Consulting Gamma Spectroscopy Tools  

Don't Do That BannerRun terminates with Lost Particles on a Rotated Universe.

Anomaly: The run dies with lost particles on a rotated universe.
History: Submitted by user.
Versions affected: MCNP5, MCNPX, MCNP6
Impact: Run terminates with Lost Particles
Work Around: Remove duplicate surfaces on the fill that are also on the universe.

Steps required to reproduce this anomaly:

Note:  Run this example in the RSICC release of each of these codes.

About the Input file:

A cylinder inside a box.  The height of the cylinder is equal to the height of the box (50 cm).  The universe is rotated.  Notice that two numbers are assigned to the top and bottom z surfaces.  This causes MCNP to loose particles.

 

rotated universe fail

 

input file

 

Click here to download the input file, iddt4 (2 kb).

 

Note the surface definition for surfaces 2 and 3 appear twice.  The work-around definition is commented out. 

 

Process to Produce Anomaly:

Verify that the surface definition for surfaces 2 and 3 are the definition with the $ comment: $lost particles on rotation

Run the input file in MCNP5 and/or MCNPX and/or MCNP6 verify the result.

 

Work around:

Modify the cell description so the duplicate surface is removed.

 

Click here to download the input file, iddt4a (2 kb).

 

Verify that the surface definition for surfaces 2 and 3 are not the definition with the $ comment:

 

Process to Demonstrate Work Around.:

Run the input file in MCNP5 and/or MCNPX and/or MCNP6 and verify the result.

 

Results obtained from our test:

MCNP6 fails.  Run is terminated because 10 particles got lost. 

rotated universe fail

 

By replacing the macrobody surface with facet 1.1, MCNP6 runs to completion.

 

rotated universe work around