Nuclear power plants and radioactive waste-disposal facilities might emit radioactive isotopes, the abundances of which exceed the natural level. To detect these increased levels, creative sampling methods as well as state-of-the-art sample preparation and measurement techniques have been developed, and are used by the HEKAL group. Atomki developed the differential radiocarbon and tritium samplers that take integrated samples from the ambient air around the Paks Nuclear Power Plant. An automatic groundwater sampling device has also been developed in order to take separately anions and cations by means of ion-exchange resins. In addition to environmental samples, hard-to-measure isotopes from low- and intermediate-level radioactive waste are also identified in our laboratory. These samples include ionexchange resins and evaporation residues from the primary circuit of the nuclear power plant. Numerous chemical extraction procedures have been adopted and developed to separate different radioisotopes of interest from the relatively high radioactive isotope abundance. Wellshielded, high-purity Ge detectors, different ultra-low-background liquid scintillation spectrometers and several mass spectrometers (noble gas, IRMS, QMS and AMS) are used in this complex field.