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Don't Do That BannerZero Lattice Element Hit Error Occurs on a Rotated Lattice.

Anomaly: The run dies with a zero lattice element hit error when a lattice is rotated.
History: Submitted by user.
Versions affected: MCNP5, MCNPX, MCNP6
Impact: Fails to run
Work Around: Modify macrobody surfaces to remove chain warning.

Steps required to reproduce this anomaly:

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

About the Input file:

A three by three xz lattice with a pitch of 20 cm.  Each lattice cell is filled with an 8 cm radius sphere of water.  A fixed source is volumetrically distributed through each of the nine spheres. A translation card rotates the lattice.

 

Rotated Lattice Fail Input

 

Note the surface definition for surface 7 appears twice.  The work-around definition is commented out. 

 

Click here to download the input file, iddt3 (2 kb).

 

Process to Produce Anomaly:

Verify that the surface definition for surface 7 is the :  rpp -10 50 -10 10 -10 50 version of the input file.

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

 

Work around:

Verify that the surface definition for surface 7 is the :  rpp -9.9999 49.9999 -9.9999 9.9999 -9.9999 40.9999 version of the input file.

 

Click here to download the input file, iddt3a (2 kb).

 

Process to Demonstrate Work Around.:

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

Run the input file in MCNP6 and verify the results.

 

 

Results obtained from our test:

MCNP6 fails.  Notice the two chain errors and that 6 surfaces were deleted.  A zero lattice element hit error is displayed:

Rotated Lattice Fail

 

With the surfaces moved, MCNP6 runs to completion:

Notice the chain errors do not appear and only 2 surfaces were deleted.  Runs to completion.

 

Rotated Lattice Fix