DTU Risø Campus Technical University of Denmark
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CHEMSIMUL is a computer program for simulation of chemical kinetics. It can model complex reactions, in particular radiolytic processes with pulse trains, or radiolysis from nuclear waste. It contains a translator module and a module for solving the resulting coupled nonlinear ordinary differential equations. There is also a module for verifying the mass balance as well as stoichiometric balance. Heterogeneous processes can be simulated by so-called exchange equations. These and Refreshable Parameters are powerful tools for calculating many physico-chemical quantities, e.g. the ionic strength. Sequental simulation is possible if the reaction volume is exposed to changing physical conditions.

The main computer platform for CHEMSIMUL is the Windows PC (XP or later). CHEMSIMUL comes with a Graphical User Interface (GUI).

Comments, improvement suggestions, and error reportings are welcome and should be directed to the authors (chemsimul@risoe.dtu.dk).

Chemsimul icon
Chemsimul output

Outstanding features:

  • Input: Standard chemistry notation
  • Unlimited number of reactions
  • Unlimited number of reactants
  • Pulse radiolysis
  • Irradiation chemistry
  • Chemistry from high level waste radiation
  • Exchange equations for physical phenomena
  • Decaying isotopes and their affiliations
  • Check of mass balance
  • Check of stoichiometric balance
  • Heterogeneous and transport processes
  • Rate constants with temperature dependence
  • Flexible plot and print expressions
  • Variable items simulated by Refreshable Parameters
  • Ionic strength calculations
  • Sequential simulation
  • Tutorials and examples

    Getting startedsee here
    Introduction to graphicssee here
    Mass balance and Stoichiometry in Chemsimulsee here
    Proper formulation of chemical equilibriasee here
    Exchange equationssee here
    Radiolysissee here
    Refreshable parameterssee here
    Dilutionsee here
    Sequential simulationsee here

    Technical issues

    List of the most common filetypes used by CHEMSIMUL.

    A classic version of CHEMSIMUL running in command mode (DOS and Linux) is available, using the same input and output format as the GUI version.
    CHEMSIMUL has successfully been tested on Linux under Wine from Redhat Enterprise 5.


    From 1. sept. 2022, the CHEMSIMUL license can be issued free of charge.

    The CHEMSIMUL license admits at any time installation and use of the most recent version of the program.

    The demo version may be used without any license.


    How to acquire CHEMSIMUL

    To be able to run the full CHEMSIMUL program, a license key is required.
    To obtain a license key, please print the standard CHEMSIMUL License Agreement.
    Fill it out, sign it and e-mail a scanned copy or post it to the address below.
    The license key will be send to the end-user by e-mail.

    Send the signed license-agreement to:

    Gitte Ravnebjerg
    Technical University of Denmark
    Risø Campus
    P.O.B. 50
    DK-4000 Roskilde
    phone: +45 4677 5502

    You will then receive the license key by e-mail.

    The full version of CHEMSIMUL, including test data, can be installed here (CHEMSIMUL version 3.90).
    The classic version of CHEMSIMUL (command-line version for DOS as well as Linux) are available free of charge for registered users.


    Demo version

    A free demonstration program called CHEMSIMUL_Demo, which has restrictions on the number of reactions and species may be used without any license.
    The documentation is the same as for the unrestricted CHEMSIMUL.
    CHEMSIMUL_Demo (including the small data examples) may be installed from here:  Chemsimul Demo version 3.90 (975 kB)


    CHEMSIMUL sample data files

    A set of sample data files for CHEMSIMUL is available here.



    An up to date model description is found as a pdf file here: Risoe-R-1630-update (413 kB)
    The official model description as a pdf file: Risoe-R-1630
    The original CHEMSIMUL report from 1984 (pdf file): Risoe-R-395.pdf (3.6 MB)

    Notes and papers:

    Modelling dilution using exchange equations in CHEMSIMUL (by P. Bouniol, CEA, Saclay): Dilution.pdf
    Radiolytic processes in cement ... (by P. Bouniol, CEA, Saclay and E. Bjergbakke, Risø): JNM-CL-0620.pdf



  • Jens V. Olsen
    System Programming Analyst
    DTU - Risø Campus, Roskilde, Denmark
  • Peter Kirkegaard
    Applied Mathematician, Ph.D.
    DTU - Risø Campus, Roskilde, Denmark
  • Erling Bjergbakke
    Bjergbakke Chemical Consulting
    Roskilde, Denmark
  • Webmaster 16. november 2022