Radiographic test problem for MCNP and other mesh-based applications

Abstract

Synthetic radiographs may be created with the Los Alamos Monte Carlo code MCNP6. A simple MCNP test problem, essentially a 10-cm high truncated aluminum cone containing three 1-cm radius tungsten spheres, each in turn containing a cylindrical void region, was devised to illustrate effects of various code options. While the radiographic test object (RTO) was initially constructed in MCNP’s traditional combinatorial solid geometry (CSG), two additional mesh-based versions were created to exercise two new “hybrid-geometry” features of MCNP6. This paper describes the RTO, user input to exercise the new features and results from several versions of the RTO geometry. To further illustrate possibilities afforded by these new features, this paper also describes MCNP-simulated proton radiography of the CYCLOPS experiment as modeled by PAGOSA, a three-dimensional multimaterial hydrodynamics computer code developed at Los Alamos. CYCLOPS, essentially a line-wave generated, steel-confined, plastic-bonded high-explosive experiment in cylindrical geometry, resulted in a collection of 20 proton radiographs. Such data is extremely valuable for PAGOSA and MCNP6 code validation efforts; the former in terms of burn fronts and reflected shocks and the latter in terms of x-ray and proton transport.