Re: Re: Deviations of flux caculation results by FLUKA and MCNP

From: Paola Sala <paola.sala_at_mi.infn.it>
Date: Thu, 31 Jan 2013 08:14:13 +0100 (CET)

Hello
with 14 MeV neutrons in most materials one would expect something better
than 10%, however
- self-shielding could make a big difference
- different choices of databases could make some difference
AND: if I understand correctly, you are testing ALL materials together in
a complex geometry, therefore differences propagate themselves from one
region to another, making it difficult to understand what and where really
happens.
Regards
Paola

> 2013 14:23:03 +0100 (CET)
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> Hi Paola,
>
> The primary particle is neutron with energy 14MeV and the particle I'm
> scoring is also neutron.
> I didn't find any pattern in the diffferences(Really troublesome:£©).
>
> Maybe I should do more careful analysis to find out the true reason.
>
> Then,from your expert view,is it possible that 10% difference of FLUKA and
> MCNP flux results are the right results?(considering material lib and
> software differences)
>
> Thanks for your kindness!
>
> Best wishes,
> Walker
>
>
>> -----Original E-mail-----
>> From: "Paola Sala" <paola.sala_at_mi.infn.it>
>> Sent Time: 2013-1-30 15:39:26
>> To: walker <wdx456_at_mail.ustc.edu.cn>
>> Cc: fluka-discuss_at_fluka.org
>> Subject: Re: Deviations of flux caculation results by FLUKA and MCNP
>>
>> Dear Walker,
>> it is difficult to answer without more information:
>> What is your primary particle? Its energy? Which particles are you
>> scoring?
>> Do you see some pattern in the differences? For instance, do they depend
>> on the position , on the material, or other?
>> Regards
>> Paola
>> > Dear all,
>> >
>> >
>> >
>> > Recently, I was trying to calculate flux distribution of a model via
>> FLUKA
>> > and MCNP respectively (in order to verify the correctness of my
>> result).
>> >
>> >
>> >
>> > The model was made up of over 100 regions and the materials included :
>> C,
>> > V
>> > , Cr, Mn, Fe, Ta, W, H, He, Li, Pb, Ni, etc.
>> >
>> > About 50 regions' fluxes were scored.
>> >
>> >
>> >
>> > I tried several ways to decrease the relative error. For example, the
>> same
>> > volume values were input into FLUKA and MCNP for flux calculation; the
>> > primary particles were increased from 1.0e6 to 1.0e7 to 1.0e8; the
>> > selfshielded material in FLUKA was also chosen.
>> >
>> >
>> >
>> > However, the FLUKA and MCNP results seemed not to match ideally: about
>> 25
>> > regions had deviation less than 1%; about 20 ones had deviation
>> between 1%
>> > and 2 %; most of the left ones had deviation beside 10% with the max
>> > deviation 19%. Both the max statistical discrepancies of FLUKA and
>> MCNP
>> > are
>> > no bigger than 1%.
>> >
>> >
>> >
>> > I' m wondering if my calculation result is correct. What's the
>> reasonable
>> > flux deviation of FLUKA and MCNP? How about 10%?
>> >
>> >
>> >
>> > Looking forward to any suggestion.
>> >
>> >
>> >
>> >
>> >
>> > Best wishes
>> >
>> > Walker
>> >
>> >
>> >
>> >
>>
>>
>> Paola Sala
>> INFN Milano
>> tel. Milano +39-0250317374
>> tel. CERN +41-227679148
>>
>
>
>


Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
Received on Thu Jan 31 2013 - 09:47:10 CET