Search found 74 matches

by Antti Rintala
Tue Dec 15, 2020 4:57 pm
Forum: Users
Topic: Negative reduced absorption macroscopic cross section
Replies: 4
Views: 556

Re: Negative reduced absorption macroscopic cross section

The reason for the behavior of abs and rabsxs is that the neutron multiplication scattering reactions usually only occur in the higher energies. Either use RABSXS and SP0, or ABS and S0 in nodal calculations. With the RABSXS and SP0, keff should be closer to Serpent results than with ABS and S0. Usi...
by Antti Rintala
Tue Dec 15, 2020 9:58 am
Forum: Users
Topic: Negative reduced absorption macroscopic cross section
Replies: 4
Views: 556

Re: Negative reduced absorption macroscopic cross section

The reduced absorption cross section can be negative, as it is calculated with Eq. 14 in https://doi.org/10.1016/j.anucene.2016.06.007. With enough scattering multiplication, the value can be below zero. Setting the value to zero will induce errors in the calculations using these group constants, if...
by Antti Rintala
Wed Dec 02, 2020 3:33 pm
Forum: Compiling and installing Serpent
Topic: Missing files to compile Serpent 2.1.31
Replies: 6
Views: 754

Re: Missing files to compile Serpent 2.1.31

That's the problem. First, extract the Serpent 2.1.0 files to a folder. Second, extract the Serpent 2.1.31 files to the same folder. Finally, try to compile Serpent 2.1.31 with make in the same folder.
by Antti Rintala
Wed Dec 02, 2020 3:07 pm
Forum: Compiling and installing Serpent
Topic: Missing files to compile Serpent 2.1.31
Replies: 6
Views: 754

Re: Missing files to compile Serpent 2.1.31

I mean that did you extract the files in the Serpent 2.1.31 update package to a folder where you already had all source files for Serpent 2.1.0 present?
by Antti Rintala
Wed Dec 02, 2020 1:35 pm
Forum: Compiling and installing Serpent
Topic: Missing files to compile Serpent 2.1.31
Replies: 6
Views: 754

Re: Missing files to compile Serpent 2.1.31

Did you apply the 2.1.31 version on top of version 2.1.0?
by Antti Rintala
Thu Nov 26, 2020 9:36 am
Forum: Users
Topic: Geometry Homogenization
Replies: 2
Views: 415

Re: Geometry Homogenization

It wasn't exactly clear what you are trying to achieve. You can calculate the homogenized group constants for the heterogeneous universe by creating the geometry and using the set gcu input card. If you are homogenizing the entire geometry, the default value of set gcu (i.e. root universe 0) is enou...
by Antti Rintala
Tue Nov 24, 2020 1:45 pm
Forum: Users
Topic: Diffusion coefficient in non fissile geometry
Replies: 6
Views: 705

Re: Diffusion coefficient in non fissile geometry

Which version of the code are you running? An error for too small number of batches is printed since 2.1.31 or the future version 2.1.32, I can't remember which one. The reason is that the program never collected the results, as it does that for the first time after batch 20.
by Antti Rintala
Tue Nov 24, 2020 1:16 pm
Forum: Users
Topic: Diffusion coefficient in non fissile geometry
Replies: 6
Views: 705

Re: Diffusion coefficient in non fissile geometry

Try setting the number of batches in set nps to 20 or more, and a value dividable by 20, for example "set nps 1000000 20".
by Antti Rintala
Tue Nov 24, 2020 12:44 pm
Forum: Users
Topic: Diffusion coefficient in non fissile geometry
Replies: 6
Views: 705

Re: Diffusion coefficient in non fissile geometry

Which diffusion coefficients are you referring to? INF_DIFFCOEF, B1_DIFFCOEF, TRC_DIFFCOEF, or perhaps CMM_DIFFCOEF?
by Antti Rintala
Mon Nov 16, 2020 10:43 am
Forum: Users
Topic: Microscopic XS of Boron-10
Replies: 4
Views: 521

Re: Microscopic XS of Boron-10

Microscopic group constant calculation features are present in Serpent with the set mdep input card. However, it doesn't currently take the distribution of the nuclides between materials correctly into account. A better microscopic group constant generation feature will be included in the next versi...