The scalability of gadolinium-doped
water-Cherenkov detectors for
nonproliferation

Among other applications, antineutrino detection offers a remote but still cooperative capability to discover or exclude operating nuclear reactors in relatively large geographic regions. The non-intrusiveness of this approach may be attractive to the country being monitored, while its persistence, wide areal coverage, and well-defined criteria for discovery or exclusion, and the opportunities it provides for scientific engagement and open dissemination of data, may be attractive to inspecting parties and the international community. Here we report the main findings of a recent study of the reactor-discovery potential for a specific technology: large-volume Gd-doped-water Cherenkov detectors. Realistic background models for the worldwide reactor flux, geoneutrinos, cosmogenic fast neutrons, and detector-associated backgrounds are included. We calculate the detector run time required to detect a small 50-MWt reactor at a variety of stand-off distances as a function of detector size. We also discuss possible improvements that could lead to increased standoff, reduced dwell-time or other operational advantages.