Colliding particles in void error in MAVRIC

[David Holler]

Hi all,

I'm modeling a neutron + photon source as a flat plate and using point locations to record doses. The flat plate is about 20 x 30 x 1 cm in size. Above the plate is a void region (20 x 30 x 35 cm). This is the entire geometry.

The model consistently stops at about 3,000 batches (100,000 particles per batch). Here is the error in the MSG file:

Note: The following floating-point exceptions are signalling: IEEE_INVALID_FLAG IEEE_DIVIDE_BY_ZERO IEEE_UNDERFLOW_FLAG IEEE_DENORMAL

And here is the error message from the OUT file:

       3019 of   5000     0.782 seconds   39.1 minutes     41F00C5248291ED5
  could not start new track            1
 Bank Entry Object:
    Particle Parameters:  
        position             = ( 8.4422373E-01,  1.0139822E+00,  4.2284375E-08)
        direction            = < 5.5217670E-01, -4.7727619E-01, -6.8359954E-01>
        polarization         = < 8.3372711E-01,  3.1609958E-01,  4.5274735E-01>
        energy               = 8.3525569E+05 eV photon      energy group =229
        weight               = 8.8693059E-03
        age                  = 0.0000000E+00 sec
        from source          = 1
        last collision, unit = -1    region = -1    mixture = -1
    SGGP Position Parameters:
        x,y,z:  8.4422373E-01  1.0139822E+00  4.2284375E-08     onBoundary? F
        u,v,w:  5.5217670E-01 -4.7727619E-01 -6.8359954E-01     surface 0
        polar:  8.3372711E-01  3.1609958E-01  4.5274735E-01
        unit=0   region=0   material=0   mixture=0
        nunum=0   kcol=0 kcore=0  nbx,nby,nbz=0 0 0
        nhole=0    kft=0   lls=0   nhl=0   nar=0
          ais=0    ihs=0
        stacka=
        stackh=
    Grid Tracker Parameters:
        x,y,z:  8.4422373E-01  1.0139822E+00  4.2284375E-08     onBoundary? T
        u,v,w:  5.5217670E-01 -4.7727619E-01 -6.8359954E-01
        polar:  8.3372711E-01  3.1609958E-01  4.5274735E-01
        cell : 311   i,j,k: 11 16 1
 Particle        46890  of batch         3020  has weight    8.8693059470350711E-003
     and is trying to have a collision in a void.
 Bank Entry Object:
    Particle Parameters:  
        position             = ( 8.4422373E-01,  1.0139822E+00,  4.2284375E-08)
        direction            = < 5.5217670E-01, -4.7727619E-01, -6.8359954E-01>
        polarization         = < 8.3372711E-01,  3.1609958E-01,  4.5274735E-01>
        energy               = 8.3525569E+05 eV photon      energy group =229
        weight               = 8.8693059E-03
        age                  = 0.0000000E+00 sec
        from source          = 1
        last collision, unit = -1    region = -1    mixture = -1
    SGGP Position Parameters:
        x,y,z:  8.4422373E-01  1.0139822E+00  4.2284375E-08     onBoundary? F
        u,v,w:  5.5217670E-01 -4.7727619E-01 -6.8359954E-01     surface 0
        polar:  8.3372711E-01  3.1609958E-01  4.5274735E-01
        unit=0   region=0   material=0   mixture=0
        nunum=0   kcol=0 kcore=0  nbx,nby,nbz=0 0 0
        nhole=0    kft=0   lls=0   nhl=0   nar=0
          ais=0    ihs=0
        stacka=
        stackh=
    Grid Tracker Parameters:
        x,y,z:  8.4422373E-01  1.0139822E+00  4.2284375E-08     onBoundary? T
        u,v,w:  5.5217670E-01 -4.7727619E-01 -6.8359954E-01
        polar:  8.3372711E-01  3.1609958E-01  4.5274735E-01
        cell : 311   i,j,k: 11 16 1
   
  ERROR: Number particles colliding in void is           10 .
         Terminating calculation.

The coordinates given are inside the flat plate source, and the boundary is at z=0.0. I've increased the Sn quadrature to 16 and refined the Denovo grid spacing to about 1 cm. I'm going to try refining the grid inside the source next. Is there anything else I can do?

Thanks and please let me know if more information is needed.

[David Holler]

This was fixed by refining the mesh inside the source. I added six planes inside the flat plate.