Code distribution

There are two versions of the Serpent code: the publicly distributed Serpent 1, for which the development and maintenance has been discontinued, and Serpent 2, which is the current development version. Obtaining the code is a two-step process:

1) Obtain a licensed copy of Serpent 1 from one of the distributing organizations (see below).
2) Contact the Serpent developer team and request a copy of Serpent 2.

The procedure is not ideal, and the main reason for distributing Serpent 2 this way is that the code is still under development and not considered quite ready for public distribution.

The main distributors of Serpent 1 are the OECD/NEA Data Bank in Europe, Japan, Korea, Mexico, Russia and Turkey, and RSICC in North America. The NEA release was issued in May 2009 (Package-ID NEA-1840, updated in January 2010) and RSICC release in March 2010 (Code Number C00757). If you are unable to obtain the code directly from the two data centers, try contacting the NEA Data Bank Computer Program Services or one of the nominated establishments in your country.

The standard license allows using the code free of charge for non-commercial research and educational purposes, but it should be noted that Serpent is not an open source code (see release notes). In addition to the research license, a provisional commercial license is available until the end of 2017. Contact the developer team for more information on commercial use of Serpent.

Source code updates are distributed directly to registered users by e-mail, and all users are encouraged to register by contacting the developer team.

System requirements

Serpent is developed under 64-bit PC Linux operating systems using the GNU and Intel C compilers. Earlier versions were also developed in MAC OS X, but some of the compatibility may have been lost. Serpent has no Windows version, but the code has been successfully compiled in Cygwin (see instructions at the discussion forum). Parallelization with the Message Passing Interface (MPI) may require installation of additional libraries, and graphical output produced by geometry and mesh plotters requires installation of the GD open source graphics library. Instructions for installing GD in various systems can be found at the discussion forum. The source code can also be compiled without MPI and GD.

Due to the internal unionized energy grid format, running Serpent 1 requires significantly more memory compared to other continuous-energy Monte Carlo codes. Transport calculations can be carried out with 100 MB to 1 GB of memory, but full-scale assembly burnup calculation may require some 5 to 10 GB of RAM. The memory demand can be reduced using built-in methods, such as grid thinning or the double-indexing of cross sections, but even then the maximum number of burnable materials is limited to a few hundred. Serpent 2 has no similar limitations, and the use of lower optimization modes allows running burnup calculations with tens or hundreds of thousands of depletion zones in a typical PC workstation.

Data libraries

The Serpent 1 installation package contains ACE format cross section libraries based on the JEF-2.2, JEFF-3.1, JEFF-3.1.1, ENDF/B-VI.8 and ENDF/B-VII evaluated nuclear data files. Continuous-energy cross sections are available for 432 nuclides at 300K, 600K, 900K, 1200K, 1500K and 1800K temperatures. S(α,β) thermal scattering data is available for light and heavy water and graphite. The data libraries are missing photon cross sections, 0K neutron cross sections needed for the DBRC method, and thermal scattering data for some commonly used research reactor materials, such as zirconium hydride and beryllium. If needed, this data can be taken from other ACE format libraries, or produced using the NJOY nuclear data processing system. Some ACE format data libraries are also available on-line:

JEFF 3.2 data libraries at the OECD/NEA Data Bank:
TENDL data libraries at the TALYS-code website:

It is recommended that the eprdata12 library distributed with MCNP6 is used for photon transport simulations until the preparation of new cross section libraries for Serpent 2 has been completed. The calculation also requires supplementary photon physics data, which can be downloaded on-line.

The "xsdir" directory files used by MCNP can be converted to Serpent format using the "" utility script found at the link page.

Radioactive decay and fission yield libraries based on the five evaluations are included in the installation package. This data is needed for burnup calculation and read from standard ENDF format files. Decay and fission yield data is also available at various public websites:

The OECD/NEA Data Bank:
The Los Alamos T2 Nuclear Information Service:
The US National Nuclear Data Center:
The IAEA Nuclear Data Centre:

Serpent 2 is currently distributed without any data libraries, but the production and testing of ACE files based on the most recent evaluated nuclear data files is under way. The libraries will also include data missing from Serpent 1 distribution (0K cross section, more S(α,β) data, heating and DPA cross sections, etc.)


The basic features of Serpent input and output format are described in the User's Manual. The code uses a conventional universe-based constructive solid geometry (CSG) model, which is very similar to MCNP and KENO-VI (the "universe" concept is basically equivalent with the "unit" definition in SCALE). Serpent has no interactive user-interface, but the input format is designed to be as user-friendly as possible, and the code checks the input for most common errors before running the simulation. Experienced Monte Carlo users are likely to understand the input at a glance, and learning to use Serpent as the first code should be relatively easy, even without prior experience with transport codes and only basic skills in reactor physics.

All numerical output produced by Serpent is written in Matlab m-format files to simplify post-processing of results. The same format is also read by various open-source math tools, such as GNU Octave.

The most recent version of the Serpent 1 User Manual can be downloaded at the main page. Serpent 2 has no separate documentation, and the pdf version of the manual will be replaced by the on-line Serpent Wiki. Additional support for users is provided at the Serpent Discussion Forum, which also contains descriptions of some of the new features and methodologies implemented in the code during the past few years.

A quick installation guide, example input files and more resources for code users can be found at the link page.

International Serpent community

Since the public release of Serpent 1.1.7 in May 2009, the user community has grown to more than 600 users in 172 universities and research organizations in 37 countries around the world. More than 80% of the registered users are also using Serpent 2. International user group meetings are organized annually in different locations. The meetings held so far are:

2011 1st International Serpent User Group Meeting in Dresden, Germany, September 15-16 2011
2012 2nd International Serpent User Group Meeting in Madrid, Spain, September 19-21 2012
2013 3rd International Serpent User Group Meeting in Berkeley, California, USA, November 6-8 2013
2014 4th International Serpent User Group Meeting in Cambridge, UK, September 17-19, 2014
2015 5th International Serpent User Group Meeting in Knoxville, Tennessee, USA, October 13-16, 2015
2016 6th International Serpent User Group Meeting in Milan, Italy, September 26-29, 2016

The 2017 meeting is planned to be hosted by the University of Florida, and more information will follow when the meeting is officially announced.


Updates in source code containing bug fixes and new features are distributed to registered users by e-mail. The updates to Serpent 2 since its release to beta-testing phase in 2012 are listed below:
2.1.28February 6, 2017
 Update to Serpent 2.1.28
2.1.27September 23, 2016
 Update to Serpent 2.1.27
2.1.26April 21, 2016
 Update to Serpent 2.1.26
2.1.25February 23, 2016
 Update to Serpent 2.1.25
2.1.24June 25, 2015
 Update to Serpent 2.1.24
2.1.23March 24, 2015
 Update to Serpent 2.1.23
2.1.22November 27, 2014
 Update to Serpent 2.1.22
2.1.21June 11, 2014
 Update to Serpent 2.1.21
2.1.20April 6, 2014
 Update to Serpent 2.1.20
2.1.19March 31, 2014
 Update to Serpent 2.1.19
2.1.18February 27, 2014
 Update to Serpent 2.1.18
2.1.17February 24, 2014
 Update to Serpent 2.1.17
2.1.16December 23, 2013
 Update to Serpent 2.1.16
2.1.15July 31, 2013
 Update to Serpent 2.1.15
2.1.14June 28, 2013
 Update to Serpent 2.1.14
2.1.13May 3, 2013
 Update to Serpent 2.1.13
2.1.12February 4, 2013
 Update to Serpent 2.1.12
2.1.11December 14, 2012
 Update to Serpent 2.1.11
2.1.10December 12, 2012
 Update to Serpent 2.1.10
2.1.9October 22, 2012
 Update to Serpent 2.1.9
2.1.8September 7, 2012
 Update to Serpent 2.1.8
2.1.7June 15, 2012
 Update to Serpent 2.1.7
2.1.6June 8, 2012
 Update to Serpent 2.1.6
2.1.5May 9, 2012
 Update to Serpent 2.1.5
2.1.4April 4, 2012
 Update to Serpent 2.1.4
2.1.3March 2, 2012
 Update to Serpent 2.1.3
2.1.2February 13, 2012
 Update to Serpent 2.1.2
2.1.1February 6, 2012
 Update to Serpent 2.1.1
2.1.0February 3, 2012
 Release of base version 2.1.0


Contact developer team:


User organizations:

Aalto University, Finland
AMEC NSS, Canada
Apollo fusion, USA
Argonne National Laboratory (ANL), USA
Areva, France
AUSY-Group, France
Axpo AG - Kernkraftwerk BEZNAU, Switzerland
Ben Gurion University of the Negev, Israel
Brno University of Technology, Czech Republic
Brookhaven National Laboratory, USA
Budapest University of Technology and Economics, Hungary
Canadian Nuclear Laboratories (CNL)
Canadian Nuclear Safety Commission
Center for Space Nuclear Research (CSNR), USA
Centro de Desenvolvimento da Tecnologia Nuclear (CDT), Brazil
Centro Tecnico Aeroespacial (CTA), Brazil
Chalmers University of Technology, Sweden
Colorado School of Mines, USA
Comision Nacional de Energia Aatomica (CNEA)
Commissariat à l'Énergie Atomique (CEA), France
Culham Centre for Fusion Energy, UK
Czech Technical University in Prague, Czech Republic
Defence Academy of the United Kingdom
Delft Nuclear Consultancy, the Netherlands
E.ON Kernkraft GmbH, Germany
École nationale supérieure d'ingénieurs de Caen (ENSICAEN), France
École Polytechnique de Montréal, Canada
École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
EDF Energy, UK
Électricité de France (EDF)
Elysium Industries, USA
ENEA, Italy
Energy Research Inc., USA
Eskom, South Africa
Federal University of State of Rio de Janeiro, Brazil
Fennovoima, Finland
Flibe Energy, USA
Forschungszentrum Jülich, Germany
Fortum Nuclear Services, Finland
FSUE VO "Safety", Russia
GDF Suez, Belgium
Georgia Institute of Technology, USA
Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH, Germany
Grenoble Institute of Technology, France
Hacettepe University, Turkey
Hanyang University, Republic of Korea
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Germany
Idaho National Laboratory (INL), USA
Idaho State University, USA
IDOM, Spain
Imperial College, London, UK
Institut de radioprotection et de sûreté nucléaire (IRSN), France
Institut de Physique Nucléaire d'Orsay, France
Institut für Festkörper-Kernphysik (IFK), Germany
Institut Jožef Stefan, Slovenia
Institute of Nuclear Energy Research (INER), Taiwan
Institute for Safety Problems of Nuclear Power Plants (ISP NPP), Ukraine
Institute for Nuclear Research (SCN), Romania
Instituto de Pesquisas Energéticas e Nucleares (IPEN), Brazil
Instituto Nacional de Investigaciones Nucleares, Mexico
INVAP, Argentina
Joint Institute for Power and Nuclear Research (SOSNY), Belarus
JRC Petten, the Netherlands
Kansas State University, USA
Karamanoglu Mehmetbey University, Turkey
Karlsruhe Institute of Technology (KIT), Germany
KEPCO Nuclear Fuel Korea
Kernkraftwerk Gösgen-Däniken AG, Switzerland
Khalifa University of Science, Technology & Research (KUSTAR), UAE
Korea Advanced Institute of Science and Technology (KAIST)
Korea Atomic Energy Research Institute (KAERI)
Korea Institute of Nuclear Safety (KINS)
Kurchatov Institute, Russia
Lappeenranta University of Technology (LUT), Finland
North Carolina State University, USA
Martingale Inc., USA
Massachusetts Institute of Technology (MIT), USA
McMaster University, Canada
Missouri University of Science and Technology, USA
National Centre for Nuclear Research (NCBJ), Poland
National Institute of Standards and Technology (NIST), USA
National Nuclear Laboratory (NNL), UK
Nippon Advanced Information Service (NAIS), Japan
Nuclear and Industrial Engineering S.r.l (N.IN.E), Italy
Nuclear Research & consultancy Group (NRG), The Netherlands
Nuclear Research Institute Rez, plc. (NRI), Czech Republic
NUCLIC - Nuclear Innovation Consultancy, the Netherlands
Nuvia Nordic AB, Sweden
Oak Ridge National Laboratory (ORNL), USA
Obninsk Institute for Nuclear Power Engineering of the National Research Nuclear University (MEPhI), Russia
OECD Nuclear Energy Agency (NEA)
Oklo, Inc., USA
Oregon State University, USA
Pacific Northwest National Laboratory (PNNL), USA
Paul Scherrer Institute (PSI), Switzerland
Penn State University, USA
Petersburg Nuclear Physics Institute, Russia
Politecnico di Milano, Italy
Politecnico di Torino, Italy
Polytechnic University of Valencia, Spain
Radiation and Nuclear Safety Auhtority (STUK), Finland
Reactive Energy, Denmark
Rensselaer Polytechnic Institute (RPI), USA
Royal Institute of Technology (KTH), Sweden
Royal Military College of Canada
RWTH Aachen University, Germany
Sandia National Laboratory, USA
Sapienza Università di Roma, Italy
Scientific Engineering Center for Nuclear and Radiation Safety (SEC NRS), Russia
SCK•CEN, Belgium
Service d'Etudes de Réacteurs et des Mathématiques Appliquées (SERMA), France
Sinop University, Turkey
Skoda JS a.s., Czech Republic
Slovak University of Technology in Bratislava, Slovakia
South African Nuclear Energy Corporation (NECSA)
Studsvik Scandpower
Subatech - Ecole des Mines de Nantes, France
SungKyunKwan University, Korea
Technical University of Catalonia, Spain
Technical University of Delft, the Netherlands
Technical University Denmark (DTU)
Technical University of Dresden, Germany
Technical University of Munich, Germany
Technical University of Vienna, Austria
Terrapower, USA
Terrestrial Energy, Canada
Texas A&M University, USA
Thor Energy, Norway
Transatomic Power Corporation, USA
Turkish Atomic Energy Authority (TAEA)
TUV SUD Industrie Service GmbH, Germany
Ulsan National Institute of Science and Technology, Korea
UMass Lowell, USA
United States Military Academy
Universidad Politécnica de Madrid, Spain
Université Joseph Fourier, France
Universitas Gadjah Mada, Indonesia
University of Birmingham, UK
University of Bologna, Italy
University of California, Berkeley, USA
University of Cambdridge, UK
University of Florida, USA
University of Genova, Italy
University of Idaho, USA
University of Illinois, USA
University of Manchester, UK
University of Michigan, USA
University of Milano-Bicocca, Italy
University of Missouri, USA
University of New Mexico, USA
University of New South Wales, Australia
University of Ontario Institute of Technology, Canada
University of Queensland, Australia
University of Sao Paulo, Brazil
University of Sofia, Bulgaria
University of Stuttgart, Germany
University of Tartu, Estonia
University of Tennessee, USA
University of Texas at Austin, USA
University of Tokyo, Japan
University of Utah, USA
University of West Bohemia, Czech Republic
University of Wisconsin-Madison, USA
University of York, UK
University of Zagreb, Croatia
Uppsala University, Sweden
US Nuclear Regulatory Commission (NRC)
Vattenfall, Sweden
VTT Technical Research Centre of Finland
VUJE, a.s., Slovakia
Warsaw University of Technology, Poland
Westinghouse Electric, USA