Time dependence in external source

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MojoJojo
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Re: Time dependence in external source

Post by MojoJojo » Mon Feb 24, 2020 9:15 pm

Ville Valtavirta wrote:
Mon Feb 24, 2020 11:31 am
Hi,

could you try re-running the simulation with just a single time interval of 100 seconds in the srctime definition?

Serpent is probably sampling points from the source file only for the first time interval (and rejecting all points that are after the end of that first interval) and the source for the further time intervals comes from the neutrons that reached the end of the previous interval.

-Ville
Ville,

It works but not for multiple energy groups. I had an option in the Matlab code to generate 'm' number of point sources with different energies at the same location. And when I do that, I'm back to the same problem :(
I tried a different definition way of the source in this way:

Code: Select all

include "./sourceTrans/source.txt" 
Where source.txt contains:

Code: Select all

src      1 n sd -1.0 0.0 0.0 sp 96.000000 -1.254604 140.995979 st 0.000000 1.000000 sb 19 0
0.0000 0.00000
5.8000e-08 0.49676
1.4000e-07 0.24109
2.8000e-07 0.02917
6.2500e-07 0.01073
9.7200e-07 0.00511
1.1500e-06 0.00195
1.8550e-06 0.00523
4.0000e-06 0.00787
9.8770e-06 0.00868
1.5968e-05 0.00474
1.4873e-04 0.02069
5.5300e-03 0.03171
9.1180e-03 0.00453
1.1100e-01 0.02491
5.0000e-01 0.02562
8.2100e-01 0.01425
2.2310e+00 0.03455
1.0000e+01 0.03241
src      2 n sd -1.0 0.0 0.0 sp 96.000000 -4.122761 130.885047 st 0.000000 1.000000 sb 19 0
0.0000 0.00000
5.8000e-08 0.49676
1.4000e-07 0.24109
2.8000e-07 0.02917
6.2500e-07 0.01073
9.7200e-07 0.00511
1.1500e-06 0.00195
1.8550e-06 0.00523
4.0000e-06 0.00787
9.8770e-06 0.00868
1.5968e-05 0.00474
1.4873e-04 0.02069
5.5300e-03 0.03171
9.1180e-03 0.00453
1.1100e-01 0.02491
5.0000e-01 0.02562
8.2100e-01 0.01425
2.2310e+00 0.03455
1.0000e+01 0.03241
.
.
And it works that way, but serpent would take up to 5 minutes to read the source file.
Name: Mohammed Mahdi
Occupation: MASc. Student
Research Interest: Liquid Fuel Molten Salt Reactor
Institution: McMaster University
Email Address: Mahdim4@mcmaster.ca

Ville Valtavirta
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Re: Time dependence in external source

Post by Ville Valtavirta » Tue Feb 25, 2020 11:43 am

MojoJojo wrote:
Mon Feb 24, 2020 9:15 pm
It works but not for multiple energy groups. I had an option in the Matlab code to generate 'm' number of point sources with different energies at the same location. And when I do that, I'm back to the same problem :(
Sorry, I'm not sure I understand, which problem?

Could you tell more about what you are trying to achieve. Are you aiming for time-dependent/transient simulations or criticality source simulations?

-Ville

MojoJojo
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Re: Time dependence in external source

Post by MojoJojo » Fri Feb 28, 2020 8:37 pm

Ville Valtavirta wrote:
Tue Feb 25, 2020 11:43 am
MojoJojo wrote:
Mon Feb 24, 2020 9:15 pm
It works but not for multiple energy groups. I had an option in the Matlab code to generate 'm' number of point sources with different energies at the same location. And when I do that, I'm back to the same problem :(
Sorry, I'm not sure I understand, which problem?

Could you tell more about what you are trying to achieve. Are you aiming for time-dependent/transient simulations or criticality source simulations?

-Ville
Hi Ville,

So I'm designing a subcritical molten salt experiment mainly to measure combined temperature reactivity feedback of:
1- Liquid fuel molten salt (doppler + density)
2- Graphite (thermalization + doppler)
Image

External neutron sources are going to be either:
1- McMaster Nuclear Reactor's neutron beam (18 energy groups to account for thermal to fast neutrons)
2- DD fusion source (3 energy groups to account for 2.1 to 3.0 MeV neutrons)

The keff is calculated in 4 ways:
1- Directly from Serpent Steady-State External Neutron Source mode (SSENS).
2- Subcritical multiplication in SSENS mode based on the detected count rate of the He-3 detectors.
3- Subcritical multiplication in Dynamic External Neutron Source mode (DYENS) with constant source based on the cumulative counts of the He-3 detectors.
4- Sjöstrand’s Area Method in DYENS mode with a pulsated source (1 Hz - 7 kHz) based on the pulse response profile of the He-3 detector.

In order to make the Serpent simulation as close as possible to real life, we need to take into account neutron source output fluctuation in the constant operation mode (up to 1% fluctuation)

The source that I wanted to define for now is the constant (but fluctuating by 1%) multi-energy group beam source. So far, I tried the following:
1- Creating 'n' number of points on a circle plane, create 'm' number of source points with different energy for each location 'n' shooting toward the reactor (use of 'sf' option):

Code: Select all

 96.000000  -4.623778 135.827227  -1.0   0.0   0.0  6.2500e-07   0.49645  0.0
 96.000000  -4.623778 135.827227  -1.0   0.0   0.0  1.0000e+00  0.25214   0.0
 .
 .
 96.000000  -3.679647 131.706018  -1.0   0.0   0.0  6.2500e-07   0.49645 14.0
 96.000000  -3.679647 131.706018  -1.0   0.0   0.0  1.0000e+00  0.25214 14.0
 .
 .
2- Defining a volumetric source:

Code: Select all

src      1 n sd -1.0 0.0 0.0 sc N11 st 0.000000 0.100000 sb 19 0
0.0000 0.00000
5.8000e-08 0.49721
1.4000e-07 0.24131
2.8000e-07 0.02920
6.2500e-07 0.01074
9.7200e-07 0.00511
1.1500e-06 0.00195
1.8550e-06 0.00524
4.0000e-06 0.00788
9.8770e-06 0.00869
1.5968e-05 0.00474
1.4873e-04 0.02071
5.5300e-03 0.03174
9.1180e-03 0.00454
1.1100e-01 0.02493
5.0000e-01 0.02565
8.2100e-01 0.01426
2.2310e+00 0.03458
1.0000e+01 0.03244
.
.
src   6000 n sd -1.0 0.0 0.0 sc N11 st 599.900000 600.000000 sb 19 0
0.0000 0.00000
5.8000e-08 0.49373
1.4000e-07 0.23962
2.8000e-07 0.02900
6.2500e-07 0.01066
9.7200e-07 0.00507
1.1500e-06 0.00194
1.8550e-06 0.00520
4.0000e-06 0.00782
9.8770e-06 0.00863
1.5968e-05 0.00471
1.4873e-04 0.02056
5.5300e-03 0.03152
9.1180e-03 0.00451
1.1100e-01 0.02476
5.0000e-01 0.02547
8.2100e-01 0.01416
2.2310e+00 0.03434
1.0000e+01 0.03222
I'm just not sure if which one is more appropriate for my purpose. Is volumetric source (horizontal cylinder 10 cm thick outside the reactor) even appropriate for beam source simulation?
Name: Mohammed Mahdi
Occupation: MASc. Student
Research Interest: Liquid Fuel Molten Salt Reactor
Institution: McMaster University
Email Address: Mahdim4@mcmaster.ca

MojoJojo
Posts: 18
Joined: Fri Jul 06, 2018 9:27 pm
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Re: Time dependence in external source

Post by MojoJojo » Tue Mar 03, 2020 7:11 am

Nevermind actually. I figured it out :)
Name: Mohammed Mahdi
Occupation: MASc. Student
Research Interest: Liquid Fuel Molten Salt Reactor
Institution: McMaster University
Email Address: Mahdim4@mcmaster.ca

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