Neutronics Analyses for the ORNL’s Spallation Neutron Source Second Target Station

Abstract

This paper presents an update of the status of the neutronics analyses performed for the Second Target Station (STS). The target station is driven with short (less than 1 micro second long) proton pulses at 15 Hz repetition rate and 700 kW proton beam power. The target will be optimized for high intensity and high resolution long wavelength neutron applications. The STS will accommodate 22 beamlines and will expand and complement the current national neutron scattering capabilities. The proton beam footprint as small as acceptable from the mechanical and heat removal aspects is planned to generate a compact-volume neutron production zone in the target, which is essential for tight coupling of the target and the moderators and for achieving high-intensity peak thermal and cold neutron fluxes. Present efforts to develop high fidelity engineering models for neutronics analyses with automatic CAD-to-MCNP conversion are described. Heating rates and radiation damage, which provide input in the engineering design are presented and the performance of the moderators is briefly addressed.