Abstract: This study took radioactive wastes from four domestic nuclear power plants as analytical objects, including spent resin, concentrate (dry salt powder), water filters, and activated carbon. Representative sampling and analysis were performed on waste samples from these plants to obtain the activity concentrations of the difficult-to-measure radionuclides (⁵⁵Fe, ⁶³Ni and ⁹⁰Sr) and key nuclides in the samples. The scaling factors of ⁵⁵Fe, ⁶³Ni and ⁹⁰Sr in different types of solid radioactive wastes from nuclear power plants were determined using the geometric mean method. Meanwhile, a comparison was made with the scaling factors of difficult-to-measure radionuclides from foreign nuclear power plants. Significant differences were found in most scaling factors. It is ultimately confirmed that domestic nuclear power plants are not suitable for directly adopting the scaling factors for difficult-to-measure radionuclides established by foreign counterparts with the same type of nuclear power plants. Instead, it is necessary to carry out independent waste sampling and measurement to determine site-specific scaling factors for difficult-to-measure radionuclides.

Key words: radioactive solid waste, difficult-to-measure radionuclide, sampling, scaling factor