Monte Carlo advances for the EOLUS ASCI project - 241

The Eolus ASCI project includes parallel, 3-D transport simulation for various nuclear applications. The codes developed within this project provide neutral and charged particle transport, detailed interaction physics, numerous source and tally capabilities, and general geometry packages. One such code is MCNP^TM which is a general purpose, 3-dimensional, time-dependent, continuous-energy Monte Carlo fully-coupled N-Particle transport code. The major new capabilities recently added to MCNP4C are: (1) Macro-bodies: a geometry simplification similar to combinatorial geometry; (2) Unresolved resonance range probability table neutron physics; (3) New ENDF/B-VI data library sampling schemes; (4) Delayed neutrons; (5) Significant electron physics enhancements; (6) Enhancements for PC computing platforms; (7) Extension of the perturbation capability to criticality calculations and cross-section dependent tallies; (8) Superimposed importance meshes so that geometries no longer need be subdivided for variance reduction; (9) Alpha eigenvalue search; (10) Parallel computing enhancements. Significant advances are also being made in the areas of modern software engineering and parallel computing. These advances are described in detail. (author)