Speaker
Description
The Second Target Station (STS) at the Oak Ridge National Laboratory’s Spallation Neutron Source is designed to become the highest peak-brightness source of cold neutrons in the world. The current conceptual design of STS consists of a segmented rotating tungsten spallation target driven by a 1.3-GeV, 700-kW short-pulsed proton beam and two coupled parahydrogen neutron moderators surrounded with water premoderators and a beryllium reflector. To advance the STS design in a timely manner and cope with a large volume of supporting neutronics calculations, we employ the most efficient computational tools that are available. Key among these tools is the Unstructured Mesh (UM) geometry capability of the radiation transport code MCNP6.2 [1]. The UM geometry capability allows us to automatically convert the computer aided design (CAD) models into high-fidelity models for neutronics calculations, reduce the time necessary to generate the models, and deliver crucial results for the subsequent thermal and structural stress analyses with high spatial resolution.
In this talk we review a wide range of applications of the UM geometry capability within the scope of the STS conceptual design. We focus on building a hybrid UM/constructive solid geometry (CSG) model to calculate energy deposition and displacement per atom (dpa) in the core vessel (CV) and CV shielding. We also demonstrate the application of CADIS/FW-CADIS variance reduction techniques to provide well-converged results in more distant regions of the shielding.
[1] C. WERNER (ed.), et al. “MCNP User’s Manual, Code Version 6.2,” LA-UR-17-29981, Los Alamos National Laboratory (2017).