The Dragon 5.1 code system and data libraries.
THEY ARE PUBLICLY AVAILABLE UNDER GNU LESSER GENERAL PUBLIC LICENSE AT https://git.oecd-nea.org/dragon.
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| Program name | Package id | Status | Status date |
|---|---|---|---|
| DRAGON 5.1 | USCD1234/02 | Tested | 08-OCT-2025 |
Machines used:
| Package ID | Orig. computer | Test computer |
|---|---|---|
| USCD1234/02 | MAC,Linux-based PC,UNIX W.S. | Gitlab |
Dragon 5.1 code system and data libraries are publicly available under the GNU Lesser General Public License at https://git.oecd-nea.org/dragon .
Dragon 5.1 distribution includes many components: GANLIB is the kernel including CLE-2000 (the data scripting language) and other application programming interfaces (API), UTILIB (the numerical toolset), TRIVAC (the finite element package), DRAGON (the lattice code based on solutions of Boltzmann and Bateman equations), DONJON (the full-core simulation package based on TRIVAC) and PyGAN (the Python 3 interface).
CLE-2000 - data and module workflow
CLE-2000 is a scripting language that drives the Dragon 5.1 toolchain. It orchestrates calculations by reading inputs, defining variables and control flow, and invoking Dragon or Donjon modules in sequence. In practice, CLE-2000 assembles geometries and libraries, configures solvers, launches runs, and manages outputs, enabling automated, reproducible lattice-to-core workflows.
Dragon - assembly/lattice calculations
The Dragon lattice code is a deterministic simulation tool for solving the Boltzmann transport equation over 1D, 2D and 3D reactor geometries. It is designed to model nuclear fuel assemblies with high geometric accuracy, using either native geometry descriptions or constructive solid geometry (CSG) through the geometry module of the SALOME platform. Dragon includes multiple transport solvers to compute particle fluxes and reaction rates, notably the collision probability method (Pij) in 1D, 2D and 3D, the method of characteristics (MOC) in 2D and 3D, the interface current method in 2D and the discrete ordinates method (SN) in 1D, 2D and 3D. It also performs resonance self-shielding, multigroup condensation and homogenization, and fuel depletion (burnup) through the solution of Bateman equations, enabling detailed tracking of isotopic evolution. The code ultimately produces few-group constants for full-core reactor simulations, for example with Donjon, and is used for assembly design and analysis.
Donjon - full-core 3D calculations
Donjon is a full-core reactor simulator that uses few-group and homogenized constants generated by Dragon to model neutron behavior across an entire reactor in three dimensions, including steady-state and transient conditions. It is designed to define fuel maps, construct and analyze detailed core models, defining assembly and node layouts, axial levels, and operating configurations such as control rod positions, thermal-hydraulic variations, and fuel burnup. Using methods such as diffusion theory, simplified PN (SPN) transport, and nodal or volume-based solvers, Donjon computes neutron flux and power distributions, the effective multiplication factor, and other key reactor parameters. The code supports burnup management by updating assembly- or node-level constants over the irradiation history, and it can be coupled with thermal-hydraulic or system codes for more comprehensive simulations. Typical outputs include power maps, peaking factors, reactivities, and detector responses, making Donjon a useful tool for core design, performance analysis, reload optimization, and reactor safety evaluations.
The Dragon 5.1 distribution provides deterministic simulation tools organized as parameterizable modules that can be integrated into CLE-2000 workflows. These modules are detailed in the Dragon 5.1 documentation, available in the doc/ folder at https://git.oecd-nea.org/dragon/5.1 .
Hébert, "DRAGON5: Designing Computational Schemes Dedicated to Fission Nuclear Reactors for Space", paper presented at the Int. Conf. on Nuclear and Emerging Technologies for Space, February 25 - 28, Albuquerque, NM (2013).
Hébert, "DRAGON5 and DONJON5, the contribution of École Polytechnique de Montréal to the SALOME platform", invited paper presented at the Third Int. Conf. on Physics and Technology of Reactors and Applications (PHYTRA3), May 12 - 14, 2014, Tetouan, Morocco (2014).
Hébert, "Applied Reactor Physics", Third Edition, Presses Internationales Polytechnique, Montréal, 2020.
Hébert, "TRIVAC, A Modular Diffusion Code for Fuel Management and Design Applications", Nucl. J. of Canada, Vol. 1, No. 4, 325-331 (1987).
| Package ID | Computer language |
|---|---|
| USCD1234/02 | C-LANGUAGE, C++, FORTRAN |
Keywords: 3D, computational scheme, computer aided design, deterministic solution, lattice, neutron transport.
