SERPENT 2.1.26 // Possible bug in OTF S(a,b) treatment

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alexandre_trottier
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SERPENT 2.1.26 // Possible bug in OTF S(a,b) treatment

Post by alexandre_trottier » Fri May 13, 2016 9:27 pm

Hi,

I am testing out the multiphysics interface with on-the-fly S(a,b). The test problem is a simple U-235 sphere in a D2O water cube, with approximate densities.

I am getting the following error message:

Code: Select all

 
**** Fri May 13 14:14:46 2016:

 - MPI task         = 0
 - OpenMP thread    = 0
 - RNG parent seed  = 1463163234
 - RNG history seed = 11534946651572738402
 - RNG history idx  = 9999

Fatal error in function OTFSabXS:

S(a,b) OTF nuclide not found for 1002.03s

Simulation aborted.

 
The maximum temperature in the problem is 650 K. This corresponds to the temperature of the .14t S(a,b) data files used.

The problem does away when the maximum temperature in the multiphysics input is reduced to 649.999 K.

I suspect a minor numerical problem on temperature interval checks.

Problem data follows.

My material cards for the water are as follows

Code: Select all

 
%Heavy water reflector, 1 g/cc 
mat water    -1 moder lwtr1 1001 moder hwtr1 1002
	1001.03c	8.6803E-04
	1002.03c	4.7715E-02
	8016.03c	2.4292E-02

therm lwtr1 0 lwe7.00t lwe7.02t lwe7.04t lwe7.06t lwe7.08t lwe7.10t lwe7.12t lwe7.14t
therm hwtr1 0 hwe7.00t hwe7.02t hwe7.04t hwe7.06t hwe7.08t hwe7.10t hwe7.12t hwe7.14t
The multiphysics input looks like this (water cube side lenght is 5cm):

Code: Select all

1 water 0
1 0.25 1
11
-2.5 -0.4 650.0
-2.0 -0.5 550.0
-1.5 -0.6 500.0
-1.0 -0.7 450.0
-0.5 -0.8 400.0
0    -1.0 300.0
0.5  -0.8 400.0
1.0  -0.7 450.0
1.5  -0.6 500.0
2.0  -0.5 550.0
2.5  -0.4 650.0
Attachments
Sab_bug_check.tgz
(1.17 KiB) Downloaded 1852 times
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Alexandre Trottier
Canadian Nuclear Laboratories

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Tuomas Viitanen
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Re: SERPENT 2.1.26 // Possible bug in OTF S(a,b) treatment

Post by Tuomas Viitanen » Tue May 17, 2016 4:31 pm

Hi,

There, indeed, is a minor problem in the temperature interval checks. I wonder how this error was not noticed previously...

Anyway, the fix is quite simple: Just change the if-sentence near line 58 of otfsabxs.c to

Code: Select all

if (RDB[sab2 + SAB_T] > T ||
	  (RDB[sab2 + SAB_T] == T && 
	   NextItem(sab2) < VALID_PTR ) )
	break;
Thank you for reporting this error! The bug fix will be included in the next update.

Tuomas

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Re: SERPENT 2.1.26 // Possible bug in OTF S(a,b) treatment

Post by alexandre_trottier » Wed May 18, 2016 12:42 am

Corrected file (missing '(' on LHS of if statement)
Tested.
Works.

Thanks.
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Alexandre Trottier
Canadian Nuclear Laboratories

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