online/offline activation results differences

From: Chris Theis <Christian.Theis_at_cern.ch>
Date: Thu, 3 Mar 2011 14:31:37 +0000

Dear colleagues,

in the course of some recent activation studies we noticed that using USRSUWEV
to calculate activity offline yields slightly different results in terms
of nuclide yield in comparison to an online calculation with FLUKA. Some
investigation showed that in the post-processing a filter is applied by
setting a threshold of 0.1% of the total activity:

THRESH =3D TOTTOT(NRN) * 0.001

I would like to understand the reasoning for this threshold because on one hand
it means that the results of a direct FLUKA output and an off-line result
are not consistent. I'm fully aware the extremely low contributions like
activities in the order of 1e-100 are of arguable meaning. Yet, the results
are still inconsistent and it's not clear to me why the filter is applied
only for the creation of the "_res.lis" file.

On the other hand I would also like to understand the reasoning for setting
the threshold value at 0.1%. If one looks at the clearance values for different
isotopes they can differ by several orders of magnitudes (e.g. from 2 to
almost 1e7) and thus, nuclides of rather low activity could still be important
from a radiological point of view. Looking at the range of the clearance values
the threshold at 0.1% seems high to me, but probably there is some reasoning
behind that I'm missing here. I would appreciate if some of the developers could
comment on this.

Thanks a lot
Chris
Received on Thu Mar 03 2011 - 16:07:08 CET

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