SERPENT Tutorial & Guide

Continuous-energy Monte Carlo from VTT. This primer covers the fundamental cards so you can run a pin cell — not a substitute for serpent.vtt.fi/docs.

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Last Updated: April 2026

Why engineers choose Serpent

Developed by VTT. These lessons get a student to a first running deck; the official documentation is the authority for card syntax and physics options.

Reactor-physics workflow

Continuous-energy transport with pin helpers and group-constant output. This primer covers the input shape you need before those extras.

Efficient engine

Optimized algorithms and parallelism enable large lattice and core models without massive compute budgets.

Lattice physics output

Once you are past this primer, Serpent can produce cross sections and diffusion coefficients for deterministic workflows. Start with a pin cell here.

Flexible geometry

CSG surfaces, cells, and pin cards. Advanced lattice, universe, and burnup lessons are archived until they are rechecked against the current VTT docs.

Quick start guides

Installation Guide

Compile Serpent on Linux/WSL and configure cluster jobs.

First Simulation

Run your first Serpent calculation with clear commentary.

Materials & Compositions

Define isotopics, moderators, and S(α,β) options.

Geometry Modeling

Build a pin cell from surfaces and cells.

Sample Serpent Input

Here's a pin-cell input in the same shape as the first-simulation lesson:

serpent
% Simple PWR pin cell (infinite lattice)

mat fuel -10.4 tmp 900
92235.06c  0.031
92238.06c  0.969
8016.06c   2.0

mat clad -6.56 tmp 600
40090.03c  1.0

mat water -0.7 tmp 574 moder lwtr 1001
1001.03c   2
8016.03c   1

therm lwtr lwj3.11t

surf 1 cyl 0 0 0.4096
surf 2 cyl 0 0 0.4750
surf 3 cuboid -0.63 0.63 -0.63 0.63 -10 10

cell 1 0 fuel  -1
cell 2 0 clad   1 -2
cell 3 0 water  2 -3
cell 99 0 outside 3

set bc 2
set pop 5000 50 20

Frequently Asked Questions

How do I obtain a Serpent license?
Licensing is coordinated by VTT, with academic distribution through the OECD/NEA Data Bank and RSICC. Commercial entities arrange supported licenses with VTT directly.
Which operating systems support Serpent?
Serpent compiles on Linux and runs on Windows via WSL2. Most production teams build on Linux clusters to take advantage of MPI scaling.
How does Serpent differ from MCNP or OpenMC?
Serpent is widely used for reactor physics, including burnup and lattice work that this primer does not cover yet. MCNP is the general-purpose transport standard; OpenMC is a Python-first API. For Serpent card syntax, use the VTT documentation.

Dive Into Serpent

Begin with installation, materials, and a pin cell. Vendor documentation stays the authority.

Get Started →View Examples →