Hi All, I’m using openmc to get a multigroup hexagonal(5 ring) problem with reflective boundary condition. the geometry is a sixth symmetry, the plotted figure is attached. my problem is that the keff and flux distribution from openmc is far away from reference. is there any restriction for openm…

I think your boundary conditions has some problems. Transmission boundary between assemblies Vacuum boundary outside of the geometry & Periodic boundary condition should be used in the two planes which is covering your 1/6 th portion of the geometry. Also, if the geometry is infinite in z-axis yo…

Thanks for your suggestions. I found the reasion is that I used complicated surface for the bottom of the geometry, geometry.xml input is given at the end. the openmc runs well when I change the bottom surface to a y-plane, but this boundary is not what i need for my benchmark problem. by the way,…

Sorry to say but i didn’t understand your problem yet. Your geometry has five rings with a pitch of sqrt (3). So is it an assembly? Or a core? & what is the problem you are facing modeling it? If it’s simply about modeling then the given examples are already enough for you i guess

Thank you for your response. the problem is a simple 5-ring min-assembly problem. the inner 4 rings are fuel pins and the outer ring is moderator pins. the figure is attached. and the outer boundary conditon is reflective. this problem is diffrent from the example because there is a large hexagon …

Follow the example, create two universes one for fuel & another with moderator (outer universe). start from ring 5 instead of ring 7 & this will give you an assembly with 5 rings. Place the universes according to your model description. Give lattice pitch sqrt (3) instead of 1.275. Put the value for…

Thank you very much. Sorry to say that my problem is a multi-pin problem (61 pins in total) WITHOUT assembly edge, so that my boundary is the outest pins’ out side. this problem is defined not similar to real hexagonal assembly in order to test hexagonal deterministic method (e.g. Hexagonal Sn met…

Hi All, could developer kindly reply if OpenMC can model this simple problem? It is just a 7-pin hexagonal problem with reflective outer boundary conditon, the difficulty for me is how to model it WITHOUT “assembly edge”. Thanks you very much. I just want to use it as a benchmark result for my d…

Just noting that this question is duplicated/answered here: [image] Set reflective boundary condition for pin by pin hexagonal problem User Support @jerrylizy You would need to set the boundary condition for each of the planar surfaces that compose the outer boundary to be…

My reply in the post that @paulromano provided above might be useful here. @jerrylizy I think some of the same issues might show up in your model too. [image] The mesh tally outputs are broken by the ''reflective" boundary type planes User Support Hi @YimingZ , A very int…

@paulromano @pshriwise Thank you very much for your reply. I guess it is very time consuming to check this kind geometry problem (recently I also did a geometry error checking in my MOC module), Thank you very much. I think this "reflective " boundary hexagonal problem is mostly required by benchm…

Reflective Boundary Hexagonal Multigroup problem

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pshriwise October 20, 2022, 5:30am 10

My reply in the post that @paulromano provided above might be useful here. @jerrylizy I think some of the same issues might show up in your model too.

Topic		Replies	Views
The mesh tally outputs are broken by the ''reflective" boundary type planes User Support	2	525	October 20, 2022
Material cannot reflect in lower universe and Particle 17551 could not be located after crossing a boundary of lattice 3 User Support	2	66	May 2, 2025
Plotting error with external hexagonal boundary User Support	3	711	May 16, 2022
Reflective boundary type of OpenMC User Support	0	568	June 27, 2019
Reflective boundary could not reflecting particles User Support	3	299	March 4, 2022

Reflective Boundary Hexagonal Multigroup problem

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