This slide presentation outlines information on developing a fluence monitoring system for ultraviolet (UV) disinfection plants based on nitrate. Specifically, the presentation investigates the applicability of nitrate as a "REF" meter at the Berenplaat Water Treatment Plant in the Netherlands which is a full scale test installation. Topics covered include: experimental test set-up; scheme of the full-scale test facilities; challenge test facilities; UV full scale test reactor; fluence and nitrate formation vs. flow at varying UVTs; REFs predicted from nitrite formation; effects of variation in nitrate and UVT; effect of UVT on REF (constant flow and lamp power setting lines); effect of UV feed water nitrate concentration on the amount of nitrite formed; lamp off situations; effects of variation in UV feed water nitrate- and UVT₂₅₄-level; UV-transmission, nitrate and disinfection action spectra; intensity distribution around MP UV-lamps at several UVT (10 mm) levels; and, radii of 30% intensity reduction.