Prospects for long-range reactor monitoring with gadolinium-loaded water-Cherenkov detectors

Antineutrino detectors are practical, non-intrusive tools capable of remotely monitoring the activity of nuclear reactors. Here we explore the sensitivity of the Super-Kamiokande water-Cherenkov detector, following gadolinium loading, to antineutrinos from a nuclear reactor complex at a distance of approximately 190 km. The livetimes required to observe the two currently operating cores in the reactor complex depend on the activity of other reactors in the vicinity, as well as on estimates of detection efficiency and background rates. Under reasonable assumptions, we find that gadolinium-loaded Super-Kamiokande could detect the flux of antineutrinos from both cores at the Takahama reactor complex at 95% confidence level in 50 (10) live days 95% (50%) of the time, or the flux from one core in 397 (73) live days, provided that each core is operating at nominal power.