Measurement and release of low-level contaminated materials from nuclear power plants into environment

Release of low-level contaminated solid materials originated from the operation or decommissioning of nuclear power plants into the environment for their recycling, reuse or liquidation is one of the main ways for the minimization of radioactive wastes production. Regulated measurement of contamination and quantitative determination of radionuclides in materials to be released are relatively complicated but manageable processes. AllDeco operates 2 measuring devices for materials release. For this purpose measuring chambers of RTM type are used for the determination of total gamma activity of radionuclides in materials. Activities of alpha and beta radionuclides are calculated by statistical results processing based on radionuclide vectors established in the laboratory for samples of similar materials. Possible spatial inhomogeneities of the contamination in measured materials can be identified by the devices software. The measurement of total gamma activity is completed by controlling spectrometric determination of present gamma radionuclides using NaI or Ge detectors. Limits for the release are measured and observed according to assigned accuracy for measuring chambers as authorized official measures. The stipulated reference levels are controlled by selective measurements of the surface alpha and beta activities and by the determination of the ratio of main gamma radionuclides. (authors)