Welcome to the home of the MCNPX code!
MCNPX is a general-purpose Monte Carlo radiation transport code for modeling
the interaction of radiation with everything. MCNPX stands for Monte Carlo
N-Particle eXtended. It extends the capabilities of MCNP4C3 to nearly all
particles, nearly all energies, and to nearly all applications without
an additional computational time penalty. MCNPX
is fully three-dimensional and time dependent. It utilizes the latest nuclear
cross section libraries and uses physics models for particle types and energies
where tabular data are not available. Applications range from outer space
(the discovery of water on Mars) to deep underground (where radiation is used
to search for oil.) MCNPX is used for nuclear medicine, nuclear safeguards,
accelerator applications, homeland security, nuclear criticality, and much more.
MCNPX is written in Fortran 90, runs on PC Windows, Linux, and unix platforms,
and is fully parallel (PVM and MPI). As a superset of MCNP4C3, MCNPX does everything
MCNP4C3 does and much more: see the 3-page MCNPX Features Summary:
MCNPX Beta Release
MCNPX (source code, executables, data) is available from this WWW site to
"beta testers" who have access to intermediate code versions. Beta versions of
MCNPX are available from "The Code" tab at the left of this web site. Beta Testers are sponsors,
collaborators, and those who take MCNPX workshops (see "Classes tab on the left.) For further
information on the Beta Test program, contact
The latest beta test version is MCNPX 2.7.E (March 3, 2011).
The principal new capabilities added since the latest RSICC release
(MCNPX 2.6.0, April 2008) are described in: "MCNPX 2.7.E Extensions"
LA-UR-11-1502.pdf, LA-UR-11-1502.doc (March, 2011).
MCNPX RSICC International Release
MCNPX is available (source code, executables, data) to nearly everyone (subject to export
controls on sensitive countries) from the Radiation Safety Information
Computational Center (RSICC)
in Oak Ridge, TN. MCNPX is packaged with MCNP5 and
the nuclear data common to both codes. Be sure to specify that you want the whole package,
MCNPX, MCNP5, and data.
The current RSICC release contains MCNPX 2.7.0 (April 2011).
The new capabilities added since MCNP4C3 (2000) and MCNPX 2.3.0 are
described in detail in the following documents:
"MCNPX 2.7.0 Extensions"
LA-UR-11-2295.pdf (.9 MB),
LA-UR-11-2295.doc (1.1 MB),
"MCNPX 2.6.0 Extensions"
LA-UR-08-2216.pdf (.9 MB),
LA-UR-08-2216.doc (1.1 MB),
and "MCNPX Extensions," (Version 2.5.0, April 2005)
LA-UR-05-2675.pdf (.6 MB),
LA-UR-05-2675.doc (1.0 MB).
We are so confident in the quality of MCNPX that we pay cash awards to the first person identifying any bug or error in the code. See the list of cash awards (4 pages):
Considering all the new MCNPX capabilities relatively few bugs have been identified. It is far easier to find an error in the predecessor codes to MCNPX than in the new capabilities added.
Last modified: July 26, 2011
To report errors on the web page, or make other comments, contact
Gregg W. McKinney / 505-665-8367