Fusion

Discussion on physics, models and calculation methods

Re: Fusion

Postby MojoJojo » Sun Oct 28, 2018 12:02 am

Hello,
I'm new to SERPENT, and I have spent quite sometime to get the "Solid 2" geomtry card to work, but with no luck! What am I doing wrong ?

Code: Select all
% surfaces

%Desired geometry

% surf 1 cyl 0.0 0.0 2.5 0.0 100
% surf 2 hexxprism 0.0 0.0 9.0 0.0 100.0

% Using "solid 2"

surf 1 cube 0.0 0.0 0.0 100
surf 2 inf

% surf 1 cyl 0.0 0.0 2.5 0.0 100.0
% surf 2 hexxprism 0.0 0.0 9.0 0.0 100.0
% surf 1 cyl 0.0 0.0 2.5
% surf 2 hexxp 0.0 0.0 9.0
solid 2 5ra nothingness
10 4 5 4 3 2
2 1E-15
body Prism cell_5ra graphite
file Prism "/home/mahdim4/Documents/5ra2.stl" 1 0 0 0
body Cylinder cell_5ra salt
file Cylinder "/home/mahdim4/Documents/5ra.stl" 1 0 0 0

% cells

cell 1 0 fill 5ra       -1
cell 2 0 outside         1
cell 3 nothingness void -2

% Desired cell configuration

%cell 1 0 salt -1
%cell 2 0 graphite 1 -2
%cell 3 0 outside 2

% material

mat graphite -1.86 moder graph
6000.09c -1.0

therm graph gre7.18t

mat salt -2.674 tmp 900.0
3007.09c  -0.0856509
4009.09c  -0.0427727
40000.09c -0.0865916
9019.09c  -0.5590432
92235.09c -0.0043833
92238.09c -0.2215584


% Other parameters

set acelib "/home/mahdim4/src/Serpent2/xsdata/sss_endfb7u.xsdata" % data library

set bc 3 % Periodic boundary condition is 3

set nfg  4  0.625E-6  5.5E-3  0.821 % # of energy groups and boundaries

set pop 2000 500 20 % Neutron population and criticality cycles:

plot 1 500 500
plot 3 500 500
plot 2 500 500 0 -205 205 -205 205
MojoJojo
 
Posts: 3
Joined: Fri Jul 06, 2018 9:27 pm
Location: Canada

Re: Fusion

Postby Jaakko Leppänen » Tue Oct 30, 2018 9:29 am

Which error message do you get?
- Jaakko
User avatar
Jaakko Leppänen
Site Admin
 
Posts: 2002
Joined: Thu Mar 18, 2010 10:43 pm
Location: Espoo, Finland

Re: Fusion

Postby M.K. » Mon Nov 05, 2018 12:37 pm

Dear Jaakko and users,

I have polyethylene as a moderator for the detector but I can not find the libraries. Could anyone suggest where to get them from?

Best Regards!
M.K.
 
Posts: 12
Joined: Mon Jan 08, 2018 4:45 pm

Re: Fusion

Postby Ville Valtavirta » Wed Nov 07, 2018 12:25 pm

I think most MCNP libraries have thermal scattering data for hydrogen in polyethylene. Those can be used in Serpent as well. The other option is to process them yourself with NJOY from ENDF-format.

-Ville
Ville Valtavirta
 
Posts: 308
Joined: Fri Sep 07, 2012 1:43 pm

Re: Fusion

Postby M.K. » Wed Nov 07, 2018 3:53 pm

Thank you, Ville!
M.K.
 
Posts: 12
Joined: Mon Jan 08, 2018 4:45 pm

Re: Fusion

Postby M.K. » Mon Nov 26, 2018 12:52 pm

Dear all,

I am running the code with an STL cylinder (2,54 cm diameter and 31 cm length) filled with He3 gas and no moderator, since I am using thermal neutrons.
The density of the gas is calculated using the ideal gas equation for the given pressure. With these input parameters I obtain reaction rate 1.40898E+03
which in my opinion is too low. The cross section on the other hand seems to be correct, according to the plot I attach here. Any feedback regarding this would be of help!

set acelib "$SERPENT_DATA/xs/sss_jeff311u.xsdata"

surf 1 cube 0 0 0 1000
surf 2 inf

mat He3 -0.000501
2003.03c -1

cell 1 0 fill detector -1
cell 2 0 outside 1
cell 3 background_platten void -2

solid 2 detector background_platten
10 4 5 4 3 2
2 1E-15

body cylinder_1 cell_detector1 He3
file cylinder_1 "/.../detector_He3.stl" 0.3 -700 -100 0

src 5 se 0.025E-6 sp 300 400 0

set nps 1000000

set srcrate 6e6

set seed 1540300529

det flux dm He3

det neutrons_per_second dm He3 dr -2 He3

det cross_section dm He3 dr -2 He3 dt 3 flux

plot 1 900 900

plot 2 900 900

plot 3 900 900

Best Regards!
Attachments
cross_section_he3.png
cross_section_he3.png (61.57 KiB) Viewed 290 times
M.K.
 
Posts: 12
Joined: Mon Jan 08, 2018 4:45 pm

Re: Fusion

Postby Jaakko Leppänen » Mon Nov 26, 2018 6:25 pm

What is your comparison? How do you figure the reaction rate is too low?
- Jaakko
User avatar
Jaakko Leppänen
Site Admin
 
Posts: 2002
Joined: Thu Mar 18, 2010 10:43 pm
Location: Espoo, Finland

Re: Fusion

Postby M.K. » Tue Nov 27, 2018 12:41 pm

It is possible that I write something incorrect here so excuse me in advance. I am in a way comparing it to our experimental results (as far as I am allowed to do it when not including the vessel and moderator, and using thermal neutrons).
The normalization to source rate is set according to our radioactive source so I expected the result to be higher. I am aware that my comparison might be irrelevant, therefore an opinion on this would be appreciated!
M.K.
 
Posts: 12
Joined: Mon Jan 08, 2018 4:45 pm

Re: Fusion

Postby Jaakko Leppänen » Thu Nov 29, 2018 6:53 pm

If you are comparing to experimental results, there several potential sources of discrepancy. The reaction rate is proportional to He3 density, so you should make sure the value is correct. Another issue is that using a mono-energetic 0.025E-6 MeV point source is not the same thing as having a spatially distributed thermal neutron source. The energy spectrum is spread over a large range of values in a region where cross sections depend on energy.
- Jaakko
User avatar
Jaakko Leppänen
Site Admin
 
Posts: 2002
Joined: Thu Mar 18, 2010 10:43 pm
Location: Espoo, Finland

Previous

Return to Methods

Who is online

Users browsing this forum: No registered users and 1 guest

cron