AbstractIn-system foil activation rates and tritium production rates were measured in an experimental lithium module (ELM), which has a 60 cm thick pseudo-cylindrical lithium metal region, at the fusion blanket neutronics facility LOTUS. Sets of two foils each made of Zr and In were irradiated at multiple locations in the central rod to measure 90Zr(n, 2n)89m + gZr and 115In(n, n′)115mIn reaction rates. Tritium measurements were done using two techniques: off-line liquid scintillation technique of Dierckx and on-line lithium glass scintillation technique, the latter technique providing only T6 (tritium from 6Li). These measurements have been analyzed both by two-dimensional and three-dimensional transport codes DORT and MCNP respectively. Though computed results broadly reproduce spatial profiles (along the central rod) of the measured quantities, differences as large as 30% are found.