RSICC CODE PACKAGE CCC-870

                                    MCNP^® and Monte Carlo N-Particle^® are registered trademarks owned by Los Alamos National Security, LLC, manager and operator of Los Alamos National Laboratory. Any third party use of such registered marks should be properly attributed to Los Alamos National Security, LLC, including the use of the ® designation as appropriate. Please note that trademarks are adjectives and should not be pluralized or used as a noun or a verb in any context for any reason. Any questions regarding licensing, proper use, and/or proper attribution of Los Alamos National Security, LLC marks should be directed to trademarks@lanl.gov.

1.            NAME AND TITLE

MCNP6.3:        Monte Carlo N–Particle^® Transport Code System Version 6.3.

 

RELATED DATA LIBRARIES 

MCNPDATA:          Standard Neutron, Photoatomic, Photonuclear, Electron/Positron, Proton, and other Light Ion Data. More information is available at https://nucleardata.lanl.gov

AUXILIARY PROGRAMS included in the distribution

Auxiliary programs are listed in Appendix E of the MCNP6.3 manual included in this distribution package and available at https://mcnp.lanl.gov/manual.htm.            

2.         CONTRIBUTOR

Los Alamos National Laboratory, Los Alamos, New Mexico.

3.         CODING LANGUAGE AND COMPUTER      

Package ID: C00870MNYCP00:    

Fortran 2018, C and C++, Linux, macOS and Windows (C00870MNYCP00).

Package ID: C00870MNYCP01:   

Executables only (no source code) for Windows, Linux, and MacOSX systems(C00870MNYCP01)

 

4.         NATURE OF PROBLEM SOLVED

The MCNP®, Monte Carlo N-Particle® code can be used for general-purpose transport of many particles including neutrons, photons, electrons, ions, and many other elementary particles, up to 1 TeV/nucleon. The transport of these particles is through a three-dimensional representation of materials defined in a constructive solid geometry, bounded by first-, second-, and fourth-degree user-defined surfaces. In addition, external structured and unstructured meshes can be used to define the problem geometry in a hybrid mode by embedding a mesh within a constructive solid geometry cell, providing an alternate path to defining complex geometry. Since the last release of the MCNP® code, major work has been conducted to improve the code base, add features, and provide tools to facilitate ease of use of MCNP6.3 as well as the analysis of results. Details regarding this release are available at https://mcnp.lanl.gov/release_630.html

5.         METHOD OF SOLUTION

Tabulated nuclear and atomic data and/or physics models are used to simulate the physics at each collision a particle undergoes during the transport process. Typically, tabulated nuclear and atomic data are used in the low-energy regime for a subset of projectile particles (e.g., neutrons, photons, light ions) and target nuclei. In particular,

• For neutrons, the isotope-specific nuclear data is most frequently represented in a continuous-energy form that accounts for all possible reaction channels including many secondary-particle production mechanisms. Additionally, thermal neutrons can make use of supplemental material-based thermal scattering data used to simulate various molecular effects influenced by chemical binding and temperature.


• For photons, the code accounts for incoherent and coherent scattering, the possibility of fluorescent emission after photoelectric absorption, absorption in pair production with local emission of annihilation radiation, and bremsstrahlung. In photon-only simulations, a thick-target bremsstrahlung model is available to approximately capture some of the physics within the photon-electron-photon cascade while providing faster speed of execution versus fully explicit and coupled photon-electron transport.


• For electrons and positrons, both a condensed-history and single-event algorithm can be used to transport the particles through materials in the system. A continuous-slowing-down model is used to estimate angular scattering and energy straggling. Knock-on electrons, x-ray production, positron annihilation, Auger electron and photon production, and bremsstrahlung photon production are modeled. For coupled photon-electron physics, electron-photon relaxation data are available, providing more detailed simulations of the ionization and subsequent relaxation process.


• For protons and other ions, some tabulated data exists for light projectiles. In comparison to neutron, photon, and electron/positron data, the availability of ion data across all possible targets is limited. For protons, several data tables are available spanning much of the chart of the nuclides. For other light-ion projectiles (1 = Z < 3), tabulated data may only exist for light-target interactions (Z < 4). Beyond the tabulated energy ranges, and for interactions with heavier target materials, the light-ion collision physics relies on model physics event generators. Where tabulated data is unavailable, such as for heavy ions and/or particles in the high-energy regime, model physics is used to simulate the physics at each collision. The threshold between low and high energy varies by particle type and tabulated data library. Depending on the projectile particle and its energy, target isotope, and physics model used, the nuclear physics simulations may go through various stages including intranuclear cascade, pre-equilibrium, evaporation, coalescence, and residual decay.

To ultimately simulate the particle tracking through the defined geometry, the collision physics interactions, and variance reduction methods, pseudo-random numbers are used to sample the underlying probability density functions that describe each of the event processes. Each history in the simulation uses a unique sequence of pseudo-random numbers and can therefore be considered independent from other histories in the simulation. Throughout the career of each computational particle, various events that occur can be tallied. The MCNP code contains numerous tallies: surface current and flux, volume flux (track length), point or ring detectors, particle heating, fission heating, pulse height tally for particle counts and energy or charge deposition, mesh tallies, radiography tallies, perturbation/sensitivity tallies, and a collection of specialized tally treatments. These tallies and their statistical uncertainties are calculated across the ensemble of independent history tally contributions.

Important standard features that make the MCNP code versatile and easy to use include a powerful general source, criticality source, and surface source; both a fixed-source and k-eigenvalue solution mode; both geometry and output tally plotters; a rich collection of variance reduction techniques; a flexible tally structure; and an extensive collection of cross-section data. All of the capabilities within the MCNP code can be used on Windows, Linux, and macOS platforms, with the majority of the features capable of parallel execution. The application areas that use the predictions of the MCNP code include (but are not limited to): radiation protection and dosimetry, radiation shielding, radiography, medical physics, nuclear criticality safety, critical and subcritical experiment design and analysis, detector design and analysis, nuclear oil-well logging, accelerator target design, fission and fusion reactor design, decontamination and decommissioning, and nuclear safeguards and nonproliferation.

6.         RESTRICTIONS OR LIMITATIONS

Known issues and limitations with this version are available in the release notes at https://mcnp.lanl.gov/release_630.html with any additional issues identified after the release notes were published identified on the webpage itself.

7.         TYPICAL RUNNING TIME

Problem dependent.

8.         COMPUTER HARDWARE REQUIREMENTS

MCNP6.3 will operate on most computers.

9.         COMPUTER SOFTWARE REQUIREMENTS

MCNP6.3 runs under Linux, macOS, and Windows. The MCNP6.3.0 distributed executables are built using the Intel compilers. More information on building this version of the MCNP code and other software dependencies is available at https://mcnp.lanl.gov/release_630.html

 

10.        REFERENCES

Included documentation in electronic format to be extracted to your hard drive:

1. J. S. Bull, J. A. Kulesza, C. J. Josey, M. E. Rising. MCNP® Code Version 6.3.0 Build Guide. Los Alamos National Laboratory Tech. Rep. LA-UR-22-32851, Rev. 1. Los Alamos, NM, USA. December 2022.
2. J. A. Kulesza, T. R. Adams, J. C. Armstrong, S. R. Bolding, F. B. Brown, J. S. Bull, T. P. Burke, A. R. Clark, R. A. Forster III, J. F. Giron, T. S. Grieve, C. J. Josey, R. L. Martz, G. W. McKinney, E. J. Pearson, M. E. Rising, C. J. Solomon Jr., S. Swaminarayan, T. J. Trahan, S. C. Wilson, A. J. Zukaitis. MCNP® Code Version 6.3.0 Theory & User Manual. Los Alamos National Laboratory Tech. Rep. LA-UR-22-30006, Rev. 1. Los Alamos, NM, USA. September 2022.
3. M. E. Rising, J. C. Armstrong, S. R. Bolding, F. B. Brown, J. S. Bull, T. P. Burke, A. R. Clark, D. A. Dixon, R. A. Forster III, J. F. Giron, T. S. Grieve, H. G. Hughes III, C. J. Josey, J. A. Kulesza, R. L. Martz, A. P. McCartney, G. W. McKinney, S. W. Mosher, E. J. Pearson, C. J. Solomon Jr., S. Swaminarayan, J. E. Sweezy, S. C. Wilson, A. J. Zukaitis. MCNP® Code Version 6.3.0 Release Notes. Los Alamos National Laboratory Tech. Rep. LA-UR-22-33103, Rev. 1. Los Alamos, NM, USA. January 2023
4. C. J. Josey, A. R. Clark, J. A. Kulesza, E. J. Pearson, M. E. Rising.MCNP® Code Version 6.3.0 Verification & Validation Testing. Los Alamos National Laboratory Tech. Rep. LA-UR-22-32951, Rev. 1. Los Alamos, NM, USA. December 2022.

Many more reference documents on MCNP^® are included in the MCNP^® REFS directory of this distribution.

directory of this distribution.

11.        CONTENTS OF CODE PACKAGE

The MCNP6.3 package is distributed on 1 DVD that can be read on Windows, Linux or macOS systems.

· Disc 1 of C00870MNYCP00 contains MCNP6.3 source code, pre-compiled executables, and reference documents.

· Disc 1 of C00870MNYCP01 contains MCNP6.3 pre-compiled executables and reference documents.

Export control regulations restrict the distribution of source code. Individuals that need the source code must include a justification as to why the source code is needed that can be included as a comment when submitting the request for the executable version. FORTRAN 2018, C, C++; Windows PC, Linux PC, macOS [Package ID: C00870MNYCP00 (full source distribution, justification required) and C00870MNYCP01 (executable-only distribution)].

 

12.        DATE OF ABSTRACT

March 2023.

KEYWORDS:       MONTE CARLO; PARTICLE TRANSPORT; COMPLEX GEOMETRY; NEUTRON, PHOTON; GAMMA-RAY; ELECTRON; ION; COUPLED; CROSS SECTIONS; PHYSICS MODELS