ウェブ1 日前 · Proton Power Upgrade reaches turning point, heads for finish line. May 7, 2024. Spallation Neutron Source, Accelerator Tunnel Extension Construction, 2023-2024. Watch on. For the past several months, the most visible component of the Proton Power Upgrade, or PPU, project for the Spallation Neutron Source, or SNS, at Oak Ridge …