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.
Radiation Shielding Examples
SCONE and Shielding
SCONE's primary strength is reactor physics (k-eigenvalue, lattice cores, depletion). For shielding problems, use type fixedSourcePhysicsPackage. However, SCONE's variance reduction capabilities for deep-penetration problems are limited compared to MCNP (weight windows, CADIS, DXTRAN). For production shielding work, MCNP is the better choice.
Slab Shield Configuration
A conceptual slab geometry: source region (0–5 cm), concrete shield (5–15 cm), detector region (15–30 cm). Uses plane surfaces with coeffs (nx ny nz d) where F(r)=n·r−d. The example shows the block-style geometry, cells, and tally structure. Verified with testLib (Water for Air/Concrete) in scone-examples/verify/tutorial_shielding_slab. official SCONE documentation.
// Conceptual slab shielding (fixed-source mode)
// SCONE's primary strength is reactor physics; for deep-penetration
// shielding, MCNP offers better variance reduction (WW, CADIS, etc.)
type fixedSourcePhysicsPackage;
pop 100000; cycles 200; XSdata ce; dataType ce;
collisionOperator { neutronCE { type neutronCEstd; } }
transportOperator { type transportOperatorDT; }
source { type pointSource; r (2.5 0.0 0.0); particle neutron; E 1.0; }
tally {
fluxRate { type collisionClerk; response (flux); flux { type fluxResponse; }
map { type multiMap; maps (xax);
xax { type spaceMap; axis x; grid lin; N 50; min 0.0; max 30.0; }
}
}
}
geometry {
type geometryStd; boundary (0 0 0 0 0 0); graph { type shrunk; }
surfaces {
P1 { id 1; type plane; coeffs (1.0 0.0 0.0 0.0); }
P2 { id 2; type plane; coeffs (1.0 0.0 0.0 5.0); }
P3 { id 3; type plane; coeffs (1.0 0.0 0.0 15.0); }
P4 { id 4; type plane; coeffs (1.0 0.0 0.0 30.0); }
boxY { id 5; type plane; coeffs (0.0 1.0 0.0 -10.0); }
boxY2 { id 6; type plane; coeffs (0.0 1.0 0.0 10.0); }
boxZ { id 7; type plane; coeffs (0.0 0.0 1.0 -10.0); }
boxZ2 { id 8; type plane; coeffs (0.0 0.0 1.0 10.0); }
}
cells {
source { type simpleCell; id 10; surfaces (1 -2 5 -6 7 -8); filltype mat; material Air; }
shield { type simpleCell; id 11; surfaces (2 -3 5 -6 7 -8); filltype mat; material Concrete; }
detector { type simpleCell; id 12; surfaces (3 -4 5 -6 7 -8); filltype mat; material Air; }
}
universes {
root { id 1; type rootUniverse; border 4; fill u<100>; }
inner { id 100; type cellUniverse; cells (10 11 12); }
}
}
nuclearData {
handles { ce { type aceNeutronDatabase; aceLibrary /path/to/your.aceXS; } }
materials {
Air { temp 293; composition { 7014.06 3.9016E-05; 8016.06 1.0409E-05; } }
Concrete { temp 293; composition { 1001.06 1.3742E-02; 8016.06 4.5953E-02; 14000.06 1.6619E-02; 20040.06 1.5025E-03; } }
}
}Geometry Notes
- Plane coeffs (nx ny nz d): F(r)=n·r−d; (1 0 0 0)=x=0; (1 0 0 5)=x=5
- Cell surfaces use signed IDs: -1 = inside, +1 = outside (for planes)
- rootUniverse border and cellUniverse fill follow the same pattern as eigenvalue inputs
- Ensure the point source
r (x y z)is inside a cell; SCONE validates at init. Cell surfaces (1 -2 5 -6 7 -8) define 0<x<5 for source region. - Root border must encompass all cells; otherwise escaping particles hit undefined material. Use a box surface for bounded domains.
Cylindrical Shield Snippet
For cylindrical geometry, use zCylinder surfaces. Inner cylinder (radius 5 cm) = source; annular region (5–20 cm) = shield; outside = detector/air. Combine with axial planes for finite height.
// Cylindrical shield (zCylinder surfaces)
surfaces {
innerR { id 1; type zCylinder; radius 5.0; origin (0.0 0.0 0.0); }
outerR { id 2; type zCylinder; radius 20.0; origin (0.0 0.0 0.0); }
topZ { id 3; type plane; coeffs (0.0 0.0 1.0 50.0); }
botZ { id 4; type plane; coeffs (0.0 0.0 1.0 -50.0); }
}
cells {
source { type simpleCell; id 10; surfaces (-1 4 -3); filltype mat; material Air; }
shield { type simpleCell; id 11; surfaces (-2 1 4 -3); filltype mat; material Lead; }
outside { type simpleCell; id 12; surfaces (2 4 -3); filltype mat; material Air; }
}When to Use MCNP Instead
For shielding problems requiring:
- Deep penetration (many mean free paths)
- Weight windows or CADIS variance reduction
- Photon transport or coupled n-gamma
- Streaming through ducts and penetrations
MCNP provides mature, well-documented variance reduction and is the industry standard for shielding.