MCNP6 moving objects. Part II: Simulations

In Part I we presented the theory and code-development upgrades for the new MCNP6 moving-objects feature. This feature facilitates automated execution of radiation transport simulations in which motion is characterized by rigid-body kinematics for three types of continuous motion: rectilinear translation, curvilinear translation, and curvilinear rotation. Models that have complicated motion paths can be simulated using motion-segment linking. Models containing up to 1000 moving objects can be executed. In addition, moving sources and delayed-neutron and delayed-gamma emission due to fission and activation reactions can be modeled. To illustrate this new capability, we present results for two sets of test models. The objective of the first set is to demonstrate object motion for a variety of dynamics conditions. These test models are executed without particle emission or transport. The updated MCNP6 geometry plotting utility is used to provide numerous plots of model geometries as they evolve with time. The second set is used to demonstrate object motion with particle emission and transport. These models examine delayed-gamma emission induced by thermal neutron irradiation of moving versions of the highly enriched uranium (HEU) and plutonium (Pu) targets used by Beddingfield and Cecil (1998) in experimental work. Our calculated results show good agreement with the measured delayed-gamma spectra. This new MCNP6 feature allows realistic simulations of object and/or source motion, which will enhance modeling realism for a variety of radiation-transport applications.