SCONE Guide
SCONE Verification Notice
SCONE is a research-oriented code with a smaller user base than MCNP, OpenMC, or SERPENT. Our examples are intended as educational guidance. For authoritative syntax, physics options, and nuclear data requirements, consult the official documentation.
Building SCONE Geometries
From Simple Shapes to Complex Systems
Building Blocks
SCONE geometry in your working input is block-based: `surfaces` + `cells` + `universes`. Surface sense (`-surface` inside, `surface` outside) is the key detail for correctness.
Basic Elements
- Surfaces: Mathematical boundaries (planes, zCylinder, zTruncCylinder, zSquareCylinder)
- Cells: Regions defined by surface combinations
- Universes: Reusable geometry components
- Lattices: Regular arrangements (like fuel assemblies)
Expanding Our Example
This snippet mirrors the style used in your BEAVRS input with z-cylinders, axial planes, and simple cells.
Enhanced Fuel Pin
geometry {
type geometryStd;
boundary (0 0 0 0 0 0);
surfaces {
fuelR { id 1; type zCylinder; radius 0.39218; origin (0.0 0.0 0.0); }
cladR { id 2; type zCylinder; radius 0.45720; origin (0.0 0.0 0.0); }
boxXpos { id 3; type plane; coeffs ( 1.0 0.0 0.0 0.63); }
boxXneg { id 4; type plane; coeffs (-1.0 0.0 0.0 0.63); }
zTop { id 5; type plane; coeffs (0.0 0.0 1.0 460.0); }
zBottom { id 6; type plane; coeffs (0.0 0.0 1.0 0.0); }
}
cells {
fuel { type simpleCell; id 10; surfaces (-1 -5 6); filltype mat; material UO2-31; }
clad { type simpleCell; id 11; surfaces (-2 1 -5 6); filltype mat; material Zircaloy; }
water { type simpleCell; id 12; surfaces (2 -3 -4 -5 6); filltype mat; material Water; }
}
}Key Concepts
- Surface combinations create regions
- Signs define inside (-) or outside (+)
- Boundary conditions control edge behavior
Universes and Lattices
Real core models reuse pins and assembly maps. `pinUniverse`, `latUniverse`, and `cellUniverse` are the fundamental composition layers.
Core Composition Pattern
universes {
root { id 1; type rootUniverse; border 1; fill u<9999>; }
pin31 { id 31000; type pinUniverse;
radii (0.39218 0.40005 0.45720 0.0);
fills (UO2-31 Helium Zircaloy Water);
}
A16E31 {
id 1631;
type latUniverse;
origin (0.0 0.0 0.0);
pitch (1.26 1.26 0.0);
shape (17 17 0);
padMat Water;
map (
31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31
... 17x17 lattice pattern ...
31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31
);
}
coreAndStructures {
id 8888;
type cellUniverse;
cells (7 8 9 10 11 12 13 14 15 16 17);
}
}Why use universes
- pinUniverse: one definition for fuel/clad/water layering, reused everywhere
- latUniverse: map pins by position (17×17 assembly layout)
- cellUniverse: group cells for RPV, barrel, baffle, core
Geometry Tips
- Surface sense: negative ID = inside, positive = outside
- Use the viz block to generate material plots and spot overlaps
- Match radii order in pinUniverse to the radial layering (fuel → gap → clad → water)
Next Steps
Geometry defines where neutrons travel. Materials define what they interact with. The Materials section covers nuclearData blocks, ZAID format, and ACE library paths.
→ Materials Guide