In the execution of disposal of low and intermediate level radioactive wastes, it is important to evaluate accurately the kind and quantity of each radionuclide in the wastes. For such an evaluation, correlation of non-gamma-emitting nuclides based on gamma-emitting nuclides is recommended and regarded as a practical method. This method necessitates a completion of a highly accurate and reliable nondestructive assay system of gamma-emitting nuclides for practical use. In 1992, in support of the new waste disposal program in Hungary, Paks NPP initiated a waste characterization program to determine the radiological properties of its radwastes. A segmented gamma scanning system has been set up to measure the gamma-emitting nuclides in 200 litre low level drums following in-drum compaction. In the framework of the program a radiochemical analysis sub-program was started to determine the long-lived non-gamma emitting radionuclides, mainly those listed in the US regulatory document (10CFR61). The radionuclides of interest have been3H,14C,90Sr,55Fe,59Ni,99Tc,129I and TRUs. Sample preparation techniques and measurement methods have been selected and used. Newly developed or adopted methods have been tested on real liquid radwaste streams such as concentrates, ion-exchange resin and sludge. The measurements taken so far have revealed brand new information and data on radiological composition of waste of WWER-type reactors. In the next stage of the characterisation program attempt will be made for providing correlation factors between the gamma and non-gamma-emitting radionuclides in different waste streams. Short description of the methods and results on waste inventory are given by highlighting the problem areas.