Lawrence Livermore National Laboratory


LLNL is developing MERCURY to be the next-generation, general-purpose radiation transport code at LLNL. The code is being developed with both programmatic and institutional funding, by a code team that is drawn from multiple organizations at the Laboratory. This approach ensures that MERCURY will be applicable for solving the broad range of transport problems that are encountered at LLNL.

The code is named after the Roman god MERCURY, who served as Zeus' messenger and who is credited with the invention of the musical scale, the lyre and pipes, boxing and gymnastics, astronomy, weights and measures, and most importantly, dice!

Mercury can transport neutrons, gamma rays, and light element charged particles using multigroup or continuous energy cross sections. Mercury can perform static and dynamic source calculations; keff and alpha eigenvalue calculations; and probability of initiation calculations. The code can compute energy deposition and isotopic depletion based on analog or expected value tallies. Tallies, variance reduction, and sources benefit from a wide array of arbitrary user defined fields for very general use capabilities.

Mercury runs efficiently on current generation massively parallel computing platforms and is being improved to enable its use on emerging platforms. Computer science enhancements include dynamically load-balancing parallel calculations, improved methods for visualizing 3-D combinatorial geometries, and implementation of inline visualization capabilities.

MERCURY uses the Monte Carlo All Particle Method (MCAPM) library, and data are stored in a pointwise format known as the Evaluated Nuclear Data Library (ENDL). The calculational constants used by MERCURY are generated by the MCFGEN processing code to produce MCF files that contain the nuclear data in both multigroup and pointwise forms. Material temperature dependence is added during the processing step. Energy deposits from nuclear reactions are precomputed by a program called ENDEP, which computes the average energy released by the reactions available for each isotope. Thermonuclear reaction rates and secondary particle distributions are provided by the TDF library.

In MERCURY, the reactions may be limited to specific subsets of the available reactions. For example, only those reactions that solely produce neutrons or only fission reactions. This keeps the decay chain down to a reasonable set of nuclides for many depletion problems.


MERCURY is not available for general download. It is an export-controlled code and is only accessible to LLNL users. Any code collaborations with third parties must be approved by the project manager.


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