Advancing the MCNP Unstructured Mesh Calculations at ORNL’s Second Target Station with Attila4MC-Cottonwood^TM

The Second Target Station (STS) at Oak Ridge National Laboratory’s Spallation Neutron Source is designed to become the world’s highest peak brightness source of cold neutrons. To design a complex radiation facility such as the STS in a timely manner, the latest radiation transport computational tools are necessary. In this work we discuss the application the new Attila4MC ® mesh generator and the new Attila4MC-Cottonwood^TM variance reduction module, both developed by Silver Fir Software, Inc. The new tools were used to generate unstructured mesh geometry and coupled neutron-photon weight windows for the subsequent MCNP simulation of energy deposition, radiation damage, and prompt dose rate for several STS components with significantly increased efficiency.