Re: [fluka-discuss]: declare own composition as beam-source?

From: Anna Ferrari <>
Date: Thu, 05 May 2016 13:28:00 +0200

Dear Uwe,

let's clarify first that with FLUKA you cannot -for a precise choice of the
authors, considered the sensitivity of the issue- simulate the behaviour of
a fission nuclear reactor system, and be able to do, for example, a safety
You can simulate fissions, but consider that fission neutrons that are
produced and transported are only prompt: all the delayed neutrons are not
considered, so that you cannot compute criticality.
This point was addressed by Alfredo in the list, for example here:
Therefore you cannot make the fuel element working as source.

Now, your problem is to compare radiation fields measured around (I suppose
around) your reactor (neutron and proton fluences and dose) with your
simulated model.
The only way I see to do this is to create a (complex) source with the right
spectrum inside the core (or, better at the surface of the core), and
calculate then with FLUKA neutron and photon fluences and doses around the
core (= in a volume external to the fuel elements). Obviously in this case
you have to remove the fuel from your FLUKA input file, in order to avoid an
additional spectrum generated by these elements.
How to describe the source depends in my opinion on where you are interested
to calculate your quantities. I gave a look at your input file and it seems
to me that -as it's reasonable- you want to look at regions outside and even
quite far from the core (regions target1, ... target5). In this case you can
describe a neutron source even at the core barrel surface(s), computed with
another code (I think you used MCNP, I see it mentioned in the input file).
In the past I had a problem exactly like yours and I followed this method,
with very good results.
You can also compute from the core a photon source... but as you know this
becomes negligible far from the core, where the photon dose is dominated by
the photons generated in neutron captures in the material around the fuel.
By the way, this depends on your particular system.... I did not
investigated it in detail.

Hope this helps... comments/corrections are welcome.
Kind regards,

Am Wed, 4 May 2016 12:10:31 +0200 (CEST) schrieb "Uwe Riesterer
(" <>:
> Dear FLUKA experts
> I´m trying to simulate the radiation of a nuclear-fuel-element during
> operation.
> The compound of this mixture is uranium-235, uranium-238 and
> high-density-polyethylene.
> So is it possible to declare my fuel-element-compound (compound M1 in my
> file) as beam-source, with its individual neutron and photon spectra?
> Or is the only way to bombard my nuclear fuel-element-mixture with thermal
> neutrons, to score the resulting particle fluence and dose (how I do it in
> input file)?
> My goal is to measure the photon and neutron radiation in real and do the
> with FLUKA.
> What´s the best way to do that?
> Or how can I modify the source.f to create my nuclear-fuel-element during
> critical operation as beam-source?
> Thanks for your help
> Uwe
> ***************************************************
> Riesterer Uwe
>Furtwangen University of Applied Sciences
> Security & Safety Engineering
> ***************************************************

Dr. Anna Ferrari
Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf e.V.
Tel. +49 351 260 2872

Vorstand: Prof. Dr. Dr. h. c. Roland Sauerbrey, Prof. Dr. Dr. h. c. Peter
Vereinsregister: VR 1693 beim Amtsgericht Dresden

You can manage unsubscription from this mailing list at
Received on Thu May 05 2016 - 15:02:50 CEST

This archive was generated by hypermail 2.3.0 : Thu May 05 2016 - 15:02:51 CEST