Neutron-photon simulations for estimating gamma heating

Separate section for discussion on gamma transport
Post Reply
eirikep
Posts: 1
Joined: Mon Nov 23, 2015 11:42 pm
Security question 1: No
Security question 2: 92

Neutron-photon simulations for estimating gamma heating

Post by eirikep » Wed Jun 08, 2016 10:32 am

Hi Serpent community, I am looking to perform neutron and photon transport simulations of a two-fluid molten salt reactor in order to estimate the total heat deposition in the blanket salt. From reading around here (especially http://tinyurl.com/j5yx253) and other places, it seems like one way of doing this would be to first perform the neutron calculation, generate a fission source text file, and use this to initiate a photon transport simulation. However, I can imagine this introducing a lot of user-dependent uncertainty in terms of energy spectrum and total photon power (is there a "set power" for photon transport as well?), and it would also leave something to be desired in terms of fission product decay treatment.

So before getting down and dirty with Serpent inputs, I wanted to ask if someone else has attempted to perform similar gamma heating calculations? And also, in light of current development status, is there perhaps a better way of doing this?


Thanks!
- Eirik

User avatar
Jaakko Leppänen
Site Admin
Posts: 2387
Joined: Thu Mar 18, 2010 10:43 pm
Security question 2: 0
Location: Espoo, Finland
Contact:

Re: Neutron-photon simulations for estimating gamma heating

Post by Jaakko Leppänen » Wed Jun 08, 2016 11:08 am

Performing this type of calculation requires accounting for the prompt gammas produced not only in fission, but also capture and inelastic scattering reactions. We are currently working on the methodology and it should be available in the distributed version within a few months or so.
- Jaakko

Karriem
Posts: 6
Joined: Wed Nov 02, 2016 10:23 pm
Security question 1: No
Security question 2: 64

Re: Neutron-photon simulations for estimating gamma heating

Post by Karriem » Wed Nov 09, 2016 11:55 pm

Hi,

I am looking at doing a coupled neutron-gamma reactor physics calculation, i.e. calculating prompt gamma fluxes and heating in a keff calculation. Could you please give me an update on Serpent's ability to do this type of calculation?

Thanks
Zain

User avatar
Jaakko Leppänen
Site Admin
Posts: 2387
Joined: Thu Mar 18, 2010 10:43 pm
Security question 2: 0
Location: Espoo, Finland
Contact:

Re: Neutron-photon simulations for estimating gamma heating

Post by Jaakko Leppänen » Wed Nov 16, 2016 2:55 pm

The physics of photon production is implemented in version 2.1.27, but the two modes are not yet combined into a single coupled neutron/photon transport mode. We've been testing the physics by running the calculations in two parts, and the photon production routine has an option to write the secondary photons produced in neutron reactions into a source file, which can be read into a second photon transport calculation.

To accomplish this, you need to set

Code: Select all

set ngamma 1
which sets on the photon production reactions. In order to produce the source file you need to define a detector:

Code: Select all

det 1 df "gamma.src" -1.0
This has to be the first detector that is defined. When you then run the calculation, you should get a photon source file "gamma.src" in binary format, which can be read into the second calculation with source definition:

Code: Select all

src 1 g sf "gamma.src" -1
Let me know if this procedure doesn't work.
- Jaakko

Karriem
Posts: 6
Joined: Wed Nov 02, 2016 10:23 pm
Security question 1: No
Security question 2: 64

Re: Neutron-photon simulations for estimating gamma heating

Post by Karriem » Fri Nov 18, 2016 6:20 pm

OK thanks!
I will try it and let you know if it works or not.

User avatar
Jaakko Leppänen
Site Admin
Posts: 2387
Joined: Thu Mar 18, 2010 10:43 pm
Security question 2: 0
Location: Espoo, Finland
Contact:

Re: Neutron-photon simulations for estimating gamma heating

Post by Jaakko Leppänen » Mon Jun 12, 2017 3:12 pm

The fully coupled neutron-photon simulation mode is now available:

http://serpent.vtt.fi/mediawiki/index.p ... set_ngamma
- Jaakko

MartinJean
Posts: 6
Joined: Thu Sep 13, 2018 6:17 pm
Security question 1: No
Security question 2: 93

Re: Neutron-photon simulations for estimating gamma heating

Post by MartinJean » Thu Mar 28, 2019 6:43 pm

Hello,

What is the difference for gamma heating between tally -26 , -12 and -4 ?
If I am interested in getting the total deposited energy after transport of neutrons and gammas, what will be the tally to output ? I would assum -10 for neutron and 26 or 12 for gamma.

In my test case I obtain the following results:
Photon -12 : 5.67 W/cm
Photon -26 : 6.13 W/cm
Photon -4 : 0.748 W/cm
Neutron -4: 10.94 W/cm
Neutron -10: 0.406 W/cm

In my deterministic code I obtain around 5.6 W/cm for the deposited gamma and around 10.8 W/cm for the produced energy before transporting it.
My understanding is the following:
Neutron -4 accounts for the energy produced by neutron and gamma before transport
Photo -12 and -26 seem quite close from the deposited gamma energy.

Thanks for your help.

Riku Tuominen
Posts: 64
Joined: Tue Feb 27, 2018 10:52 am
Security question 1: No
Security question 2: 93

Re: Neutron-photon simulations for estimating gamma heating

Post by Riku Tuominen » Mon Apr 01, 2019 12:25 pm

First of all, -4 is used only for neutrons to calculate the energy deposition using KERMA coefficients and -10 gives the energy deposition in ONLY elastic and inelastic scattering. For gammas, you have two choices -26 or -12. -26 uses KERMAs and -12 gives an analog estimate for the energy deposition by photons. -26 and -12 should give similar results in most cases but -12 is more accurate. In conclusion, you should use -4 for neutrons and -12 for photons.

However, -4 does not account for the delayed fission components (delayed betas/gammas) and if you normalize your results to power (set power) the deposited total energy (power) will not be equal to the power given with set power. In order to be able to calculate the energy deposition more accurately you need the energy deposition treatment presented in https://doi.org/10.1016/j.anucene.2019.02.003. This new treatment will be available in the upcoming Serpent version which will be released in the near future. Along with the new version, you will need new cross section data since the standard ACE-format does not include all the data needed by the new energy deposition treatment.

MartinJean
Posts: 6
Joined: Thu Sep 13, 2018 6:17 pm
Security question 1: No
Security question 2: 93

Re: Neutron-photon simulations for estimating gamma heating

Post by MartinJean » Wed Apr 03, 2019 12:36 pm

Thanks for your explanation. I now get consistent results with my deterministic code.
I just need to find a way to get new evaluation with Gadolinium and Plutonium gamma production that are lacking in my evaluation.

Any idea about a possible date for this new Serpent release ?

Post Reply