Cyclus is the next-generation agent-based nuclear fuel cycle simulator, providing flexibility to users and developers through a dynamic resource exchange solver and plug-in, user-developed agent framework.

The goal of Cyclus is to enable a broad spectrum of fuel cycle simulation while providing a low barrier to entry for new users and agent developers. Cyclus engages with potential module developers and encourages them to join a vibrant community in an expanding ecosystem. Users and developers are always welcome and encouraged to use or contribute to the Cyclus project.

The Cyclus project repository is located at

Project repository is located at


December 13, 2016: Cyclus v1.5.0 is released

July 6-8, 2016: Technical workshop on Dynamic Fuel Cycle in Paris, France

August 13, 2015: Cyclus included in FY2016 workscopes for the NEUP program

July 21-24, 2015: Joint workshop with CLASS project held in Madison, WI

June 10, 2015: First Cyclus user tutorial and developer tutorial are held at the 2015 ANS Annual Meeting in San Antonio, TX

June 7, 2015: Cyclus v1.3.1 is released

Try It

You can run a simulation right now from the comfort of your own browser. Just paste in any Cyclus input file (or use the default one below) into the text box below and click submit. A job ID will be created and displayed - you should keep track of this in order to retrieve your results. The job table below updates automatically every 30 seconds, or you can refresh this page. It contains all submitted jobs - their status, output, and database (if completed) with some useful links:

  • Clicking on the job ID link downloads the input file for the job.
  • Clicking on the Status link shows the simulation output - useful for diagnosing failures.
  • For completed jobs, download the database in a zip file by clicking the Results link. You can check out Understanding the Database for information on working with the data.

Cyclus input file:

Contact Us



Support for this research has included funding received from:

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