Advanced simulations for the shielding design of the Target-Viewing Periscope for ORNL STS

The Second Target Station (STS) at ORNL's Spallation Neutron Source is a next-generation facility designed to provide world-leading cold neutron beams for materials science, utilizing a 700-kW proton beam on a rotating tungsten target. A key diagnostic component, the Target-Viewing Periscope (TVP), provides a direct optical view of the target edge, enabling measurements of the proton beam profile important to remotely inspect the high-radiation target area in real time. We present an advanced Monte Carlo simulation workflow, incorporating variance reduction and unstructured mesh modeling, to analyze the complex radiation environment around the TVP. This work calculates key radiation quantities including heat load, DPA, activation, and residual dose rate maps. We will discuss the impact of shielding modifications in the central TVP section on the activation of adjacent components, which informs component lifetime and maintenance strategies. Furthermore, the temporal evolution of the photon dose rate field will be presented. This analysis provides critical insights for determining safe access windows and planning the post-irradiation handling and maintenance of the TVP assembly.