Cyclus User Guide

This guide covers the basics of installation, creating simulation input files, and running them. If you haven’t already, you should take a look at Fundamental Concepts in Cyclus.

Installing Cyclus

Running Simulations

You can also run a simulation right now from the comfort of your browser here!



Collections of archetypes are provided by various teams and individuals for use by Cyclus users.


The Cycamore library of archetypes is provided by the Cyclus development team as a basic set of archetypes for modeling simple nuclear fuel cycles.

Cyclus Testing

The Cyclus kernel includes some archetype for testing the basic functionality of the kenel.

Third-Party Archetypes

Several useful archetypes have been developed by the community outside the purview of the Cyclus project itself and are listed here. These archetypes do not necessarily adhere to the same standards of quality (documentation, testint, etc.) as Cyclus and Cycamore code - users are responsible for evaluating their suitability.

The University of Texas - Austin is developing a set of archetypes for fuel fabrication and reactors that rely on interpolation tables for more accurate prediction of fresh fuel compositions and estimates of fuel depletion.
The University of Tennessee is working with Oak Ridge National Lab to develop archetypes that will use ORIGEN calculations to improve the estimate of nuclear fuel properties.
Mbmore Archetypes (
Facility archetypes that utilize a random number generator to create non-deterministic behaviors. General methods controlling the behavior (including random number generation and Gaussian distributions) are defined in the behavior functions.
  • :mbmore:RandomEnrich Based on cycamore enrichment facility, it can have variable tails assay, and bidding behavior can be set to occur at Every X timestep or at Random timesteps.
  • :mbmore:RandomSink Based on cycamore sink facility, it can accept multiple recipes, has modifiable material preference, material request behavior can be set, trading can be suppressed before a specified timestep, material requests can occur at Every X timestep or at Random timesteps, and quantity requested can be varied using a Gaussian distribution function.
rwc Archetypes (
This is a collection of miscellaneous archetypes made by Robert Carlsen to support optimization work and other side projects:
  • :rwc:LookInst This archetype allows the user to specify an arbitrary power capacity time series that the institution will automatically deploy power generating facilities (of multiple types) to match. It uses a look-ahead mechanism to see if its chosen deployments were not “good” and adjusts its deployment decisions accordingly. This archetype currently requires rwcarlsen/cyclus#restart branch of Cyclus to work.
  • :rwc:FleetReactor This reactor models an entire reactor fleet as a single, homogenous unit. Like the Cycamore reactor, it just uses static, user-specified compositions for fresh and spent fuel. Refueling is incremental - occuring every time step. It is approximately a continuous flow fleet model much like the way system-dynamics simulators represent facilities. It “pretends” to be many reactors to the Cyclus kernel - allowing other agents to deploy/decommission single-reactor units, but these single-reactors just adjust the size/capacity of the homogenous fleet.
  • :rwc:PatternSink Pattern sink is identical to the Cycamore sink facility except it has an additional parameter that allows the user to control the frequency with which the facility requests material - i.e. the user can tell the facility to only request material every Nth time step.
  • :rwc:Storage This facility is very similar to the Cycamore storage facility, and was originally created before Cycamore’s existed. It has slightly more careful handling of discrete material objects (e.g. not ever splitting them) and is a bit more sophisticated with respect to resource exchange for offering/bidding its inventory. It would be good to use implementation details from this archetype to improve the Cycamore storage archetype.