Re: [fluka-discuss]: Neutron transport across a wall

From: Stefan E. Mueller <stefan.mueller_at_hzdr.de>
Date: Sun, 25 Aug 2024 20:47:44 +0200 (CEST)

Dear Beatrice,

my take on this would be that the "Spot weight" is useful when there are
several "SPOTBEAM" cards present, and the weight is then calculated using
the several "Spot weight" values (which get normalized to "1.").

So in your case there is only one "SPOTBEAM" card present, so I assume
that the "3.2E10" get renormalized to "1.", and the scorers give results
in "neutrons/cm2/primary", so you would need to multiply the values by
3.2E10 neutrons/s to get "neutrons/cm2/sec" (using the fields "Y Norm" or
"Norm" in FLAIR's plot section.

The manual is not so specific about the "Spot Weight" field, so I might be
wrong, but this would be the behavior I would expect.

Cheers,

         Stefan

--
Stefan E. Mueller
Department of Information Services and Computing - Computational Science
and Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf
Tel: +49 (0351) 260 3847
Stefan.Mueller_at_hzdr.de
http://www.hzdr.de
Vorstand: Prof. Dr. Sebastian M. Schmidt, Dr. Diana Stiller
Vereinsregister: VR 1693 beim Amtsgericht Dresden
On Fri, 23 Aug 2024, Beatrice Pomaro wrote:
> 
> Dear Fluka experts,
> I would like to simulate the diffusion of a certain flux of fast neutrons
> across a concrete wall (please, see attached .inp file).
> I would like to use a neutron spectrum that consists of 1 kinetic level,
> only: a fast neutron flux of 3.2 × 10^10 n∕(cm2 s).
> I am using the SPECSOUR and SPOTEBAM cards to do that, under the forum's
> suggestion.
> In the attached file I have assigned the input fast neutron flux of 3.2 ×
> 10^10 n∕(cm2 s) in WHAT(3) of card SPOTEBAM, for which I read from the
> manual it corresponds to the beam spot weight (numb! er of par ticles).
> When I draw the 1D plot of the flux attenuation across the wall (which is
> from -40 to 40 along Z direction) I get, however, values of the output
> neutron flux of the order of 10^-4 n/(cm2 s).
> I was expecting to have fluxes of the order of 10^10 as the input source. Is
> there a normalization factor that I have to consider in the results?
> Many thanks for your help,
> Kind regards,
> Beatrice
> 
> --
> **************************************************
> Ing. Beatrice Pomaro
> 
> Universita' degli Studi di Padova
> Dipartimento di Ingegneria Civile, Edile e Ambientale
> Via F. Marzolo, 9 - 35131 Padova (Italy)
> tel.: +39 049 8275601
> e-mail: beatrice.pomaro_at_dicea.unipd.it
> 
>

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Received on Sun Aug 25 2024 - 22:35:20 CEST