Equilibrium xenon in decay steps

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jan.frybort
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Equilibrium xenon in decay steps

Post by jan.frybort » Tue Aug 22, 2017 3:35 pm

Hi.
Would it be possible to implement an option to set xenon to equilibrium concentration for decay steps (essentially zero)? The reason for this is to obtain HZP state with zero xenon from a depletion calculation on nominal parameters. Thank you.
Jan

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Jaakko Leppänen
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Re: Equilibrium xenon in decay steps

Post by Jaakko Leppänen » Tue Aug 22, 2017 5:43 pm

I've never thought about this. How does it behave now? Does the concentration simply fall from the value defined by the previous burnup step?

I guess it would be sufficient to simply reset the concentration any time the equilibrium calculation is on. Or are there some cases where you would need equilibrium concentration for burnup steps but explicitly calculated concentration for decay steps?
- Jaakko

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Re: Equilibrium xenon in decay steps

Post by jan.frybort » Tue Aug 22, 2017 5:51 pm

You are right. Currently the concentration falls from the value of the previous depletion step (actually for short decay steps it increases due to I135 decay).

I just thought about this as a possible workaround for my current issue. I believe the most general solution would be to allow setting power for the branch-off states and optional equilibrium xenon calculation for the branch-off calculations.

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Re: Equilibrium xenon in decay steps

Post by Jaakko Leppänen » Wed Aug 23, 2017 9:53 am

I'll look into this. Setting the normalization in the branch cards could be a useful feature.

If your depletion steps are not very short, you could define an extra decay step that allows the Xe-135 concentration to fall to zero and branch to a point after that.
- Jaakko

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Re: Equilibrium xenon in decay steps

Post by Volodymyr Gulik » Mon Aug 28, 2017 4:25 pm

Hello Jaakko.

I have task to calculate the group constant generation for VVER-1000. Also, I do not have much experience in this type of simulations.

In my case, I have the list of burnup points (for example, 1, 2, 3, 4, 5, 10, 20, 30). I need to calculate the branch with follow conditions: 1. Coolant temperature = 575 K; 2. Fuel temperature = 575 K (for fuel1 and fuel2); 3. Coolant without boron; 4. Xe-135 = 0; Sm-149 = 0. There is my branch below:

% --- Branch ew575f575b00x0s0

branch ew575f575b00x0s0
repm cool cool_0B
var BOR 0
stp fuel1 -10.55 575
stp fuel2 -10.37601 575
var TFU 575
var TMO 575

I did not undarstand your explanation above "... you could define an extra decay step that allows the Xe-135 concentration to fall to zero and branch to a point after that ...". Could you explain me how I can calculate my branch for zero concentrations of Xe-135 and Sm-149 in detail?

Volodymyr

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Re: Equilibrium xenon in decay steps

Post by Reem » Wed Feb 07, 2018 9:37 pm

Volodymyr Gulik wrote:Hello Jaakko.

I have task to calculate the group constant generation for VVER-1000. Also, I do not have much experience in this type of simulations.

In my case, I have the list of burnup points (for example, 1, 2, 3, 4, 5, 10, 20, 30). I need to calculate the branch with follow conditions: 1. Coolant temperature = 575 K; 2. Fuel temperature = 575 K (for fuel1 and fuel2); 3. Coolant without boron; 4. Xe-135 = 0; Sm-149 = 0. There is my branch below:

% --- Branch ew575f575b00x0s0

branch ew575f575b00x0s0
repm cool cool_0B
var BOR 0
stp fuel1 -10.55 575
stp fuel2 -10.37601 575
var TFU 575
var TMO 575

I did not undarstand your explanation above "... you could define an extra decay step that allows the Xe-135 concentration to fall to zero and branch to a point after that ...". Could you explain me how I can calculate my branch for zero concentrations of Xe-135 and Sm-149 in detail?

Volodymyr
Hello,

Can you please confirm if you solve the problem regarding Sm concentration?

Reem

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Re: Equilibrium xenon in decay steps

Post by Jaakko Leppänen » Sun Feb 11, 2018 1:11 pm

This problem has not yet been fixed in 2.1.29, but the next update will include options to perform branches with zero poison concentrations.
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Re: Equilibrium xenon in decay steps

Post by jan.frybort » Tue Feb 27, 2018 2:44 pm

Thank you Jaakko, for releasing new Serpent 2.1.30. I was able to find in the versions.txt file that there are new features implemented, but I didn't find any documentation. Could you, please, provide some information regarding these new features? Thank you.
Jan Frybort

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Re: Equilibrium xenon in decay steps

Post by Jaakko Leppänen » Thu Mar 01, 2018 2:13 pm

See the description of the branch card in Serpent wiki. These are the "xenon" and "samarium" options.
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Re: Equilibrium xenon in decay steps

Post by jan.frybort » Tue Mar 27, 2018 3:26 pm

Thank you Jaakko, for pointing me to the documentation. It is really possible now to set Xe concentration to 0. Could you still, please, consider implementing the feature to set power for normalization for branch-off calculations? It would be the best to get two results for branch-off calculations. One (predictor step) with material composition including Xe from the depletion calculation reflecting only changes to temperatures etc. Second result (corrector step) would add change to Xe concentration due to different normalization power. Thank you.
Jan Frybort

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