PyNE 0.2 Release Notes

PyNE 0.2 is the second release of Python for Nuclear Engineering project after an additional six months effort. PyNE is a free and open source (BSD licensed) project whose goal is to become a necessary package in the computational nuclear engineer’s toolkit. It is meant to play nicely with existing, industry standard nuclear engineering tools. PyNE is meant to be both fast and useful.

Release highlights:

  • Multicomponent enrichment solvers.

  • Simple simulation input file generator.

  • CMake based build system.

Please visit our website for more information:

New Features

Basic Nuclear Data (pyne.dbgen)

The nuc_data_make utility has been expanded to now include EAF cross section data from the IAEA [EAF] as well PNNL’s recent materials compendium [MATCOMP].

Nuclear Data (

Natural isotopic abundance ratio information has been exposed via the natural_abund() function.

Material (pyne.material)

Materials have been revamped to now include an attrs namespace which can store arbitrary metadata. In light of this, the name field has been removed as names may now be stored via mat.attrs['name']. Materials now follow the convention that all extrinsic variables should be stored in the attrs while intrinsic (physical) properties may be stored as class-level fields. Thus density has been added as a class-level field. A skeletal MultiMaterial class has also been introduced to handle many materials simultaneously without mixing their constituent nuclides.

Simple Simulation Input (pyne.simplesim)

The simplesim package provides modules for the definition of a system (its geometry and material composition), the definition of simulation parameters, and for the generation of input files to codes that can perform such simulations (MCNP, Serpent, MCODE, etc.).

Mulicomponent Enrichment (pyne.enrichment)

The enrichment module contains tools for defining and manipulating enrichment cascades. The Cascade class is a simple container for storing parameters which define and enrichment setup. These include feed, product, and tail materials, target enrichments, and separation factors. The main functions in this modules computes the total flow rate and separation factors from an initial cascade. Other helper function compute relative flow rates and nuclide-specific separation factors. Both a standard numeric solver and a fast symbolic solver have been implemented.

Cross Section Interface (pyne.xs)

The cross section interface has been refactored to include the concept of data sources, which expose information and manipulation routines for all valid reactions. To date null, simple, Cinder, and EAF data sources have been implemented. The cross section cache XSCache has been refactored to pull raw data from data source classes.

Preliminary NJOY Integration (pyne.njoy)

NJOY input file generation has started to be integrated with the inclusion of PyNjoy into PyNE. Some PEP8 based-clean up has already occured. More work will likely follow.

JsonCpp (pyne.jsoncpp)

A Cython wrapper around the JsonCpp project, which is automatically included in PyNE. This provides an in-memory, C++ level representation of JSON objects. This is mainly used as a Python independent C++ dictionary to store arbitrary metadata. Interoperation in both Python and C++ is very natural. For more information please refer to [JSONCPP].

GUI Tools (pyne.gui)

The aceviewer tool is now installed as a command line utility, available anywhere on the system.


This release contains code written by the following people (in alphabetical order). An (*) indicates a first-time contributor to PyNE.

  • Elliott Biondo*

  • Christopher Dembia

  • Robert Flanagan

  • Katy Huff*

  • Matt McCormick*

  • Eric Relson

  • Paul Romano

  • Anthony Scopatz

  • Paul Wilson

  • John Xia*

Additionally, we would like to thank the following people for their inspiration, guidance, and testing:

  • Seth Johnson

  • Ronald J. McConn Jr (for help with PNNL Materials Compendium)

  • Joshua Peterson

  • Rachel Slaybaugh

  • Nick Touran

  • Morgan White



A.B. Pashchenko and H. Wienke, “FENDL2/A-MCNP, FENDL2/A-VITJ_E and FENDL2/A-VITJ_FLAT, the processed FENDL-2 neutron activation cross-section data files”, report IAEA-NDS-174, International Atomic Energy Agency, March 1997.