MAVRIC error: negative distance to cross the array boundary

[Sander Miller]

Hi all,

I have an HTGR model that I use frequently in both KENO-VI and MAVRIC (SCALE 6.3.1/6.3.2). 

I have no problems in KENO. But in MAVRIC, after ~100 batches and ~10,000 perbatch, I get the below error and it cuts my run short:

  ***** error ***** sggp message number k6-259 follows:

neutron 0 from generation 0 located in unit 30

at position x =  number    y =  number    z = number 

in array 2052 boundary unit 112 global region 54

at boundary position xary = number    yary = number  zary = number 

has a negative distance to cross the array boundary

This could be due to an array boundary overlapping a hole.

The documentation gives this explanation for the error:

• This [error] can be caused by the array boundary intersecting a hole, of by round off in computing the coordinates of the point in the unit containing the array boundary for large dodecahedral arrays.

I do not use holes in my geometry, but I do use dodecahedral (and hex) arrays. How can I address this rounding error? I need to decrease the uncertainty in my shielding calculations, and this has been the limiting factor.