Discussion forum for Serpent users

Can you send me the input by email?

It's very difficult to say why your calculations are running out of memory. One thing to check is that you are really running a single MPI task for each node. This is important, because the number of tasks multiplies the memory consumption, so you shouldn't run multiple tasks in the same memory spac...

I completely missed the part about using the same random number seed. Yes... adding extra layers will affect the random number sequence when surface tracking is in use. The "set dt 1" card enforces the use of delta-tracking for every sampled track and should result in perfect reproducibility.

If this is a full-core model, why do you need the reflective boundary condition? The error on insufficient fissile material is most likely related to the sampling of initial fission source. Serpent samples source points uniformly throughout the geometry, and accepts the points that land on fissile m...

That's right.

You can also specify the dividing volume in the dv entry of the detector card. Since the volumes are in general not known, the divisor is set to 1 by default. This works also for a Cartesian mesh detector, but not for a cylindrical mesh, where the cell size depends on radius.

The 13th column in Serpent 1 is the number of scores. This is not printed in Serpent 2.

The detector gives you the flux integrated over space, energy and direction (and time). The values are not divided by volume by default.

Your gbuf value is very large. This value determines the buffer for storing secondary gammas. In your case Serpent prepares to transport 1 billion photons per every neutron, which seems excessive. This is probably what causes memory allocation to fail.

The first error is related to boundary conditions. Reflective boundary condition ("set bc 2") requires that the outer boundary is comprised of a surface that can be used to form a repetitive lattice. The second error means that the surface type is not supported by the surface source routine. Could y...

Are you using reflective or periodic boundary conditions?

Also, source convergence in this type of calculations may be very slow. Have you tried tried repeating the calculations to see if the differences are consistent?