Conservative no-effect concentrations were derived for nine radionuclides, four generic organisms (terrestrial plant and animal and aquatic plant and animal) and six environmental compartments (air, soil, fresh water, marine water, freshwater sediments and marine sediments). The concentrations were calculated using the concentration ratio (CR) approach that is used in both FASSET and RESRAD-BIOTA. In the CR approach, a single transfer factor is used to predict concentrations in plants or animals from concentrations in soil or water. Most of the CR values required for the calculations were taken from FASSET documentation. Because of the importance of tritium and C-14 in the context of CANDU reactors, CR values for these radionuclides were derived from specific activity (SA) concepts. Sediment partition coefficient (Kd) values, which were used to derive no-effect levels for sediments from the levels for water, were chosen to be the best-estimate values from the IMPACT database. Dose conversion coefficients (DCCs) were taken from FASSET and the dose rate benchmarks used were those recommended by UNSCEAR. The results provide environmental concentrations below which no detrimental effects are expected on non-human biota at CANDU sites in Canada.