Neutronphoton simulations for estimating gamma heating
Neutronphoton simulations for estimating gamma heating
Hi Serpent community, I am looking to perform neutron and photon transport simulations of a twofluid 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 userdependent 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
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
 Jaakko Leppänen
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Re: Neutronphoton simulations for estimating gamma heating
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
Re: Neutronphoton simulations for estimating gamma heating
Hi,
I am looking at doing a coupled neutrongamma 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
I am looking at doing a coupled neutrongamma 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
 Jaakko Leppänen
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Re: Neutronphoton simulations for estimating gamma heating
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
which sets on the photon production reactions. In order to produce the source file you need to define a detector:
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:
Let me know if this procedure doesn't work.
To accomplish this, you need to set
Code: Select all
set ngamma 1
Code: Select all
det 1 df "gamma.src" 1.0
Code: Select all
src 1 g sf "gamma.src" 1
 Jaakko
Re: Neutronphoton simulations for estimating gamma heating
OK thanks!
I will try it and let you know if it works or not.
I will try it and let you know if it works or not.
 Jaakko Leppänen
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Re: Neutronphoton simulations for estimating gamma heating
The fully coupled neutronphoton simulation mode is now available:
http://serpent.vtt.fi/mediawiki/index.p ... set_ngamma
http://serpent.vtt.fi/mediawiki/index.p ... set_ngamma
 Jaakko

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Re: Neutronphoton simulations for estimating gamma heating
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.
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.

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Re: Neutronphoton simulations for estimating gamma heating
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 ACEformat does not include all the data needed by the new energy deposition treatment.
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 ACEformat does not include all the data needed by the new energy deposition treatment.

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Re: Neutronphoton simulations for estimating gamma heating
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 ?
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 ?