DETECTION OF UNDECLARED NUCLEAR MATERIAL AND ACTIVITIES IN CAPABLE HOT CELLS USING ENVIRONMENTAL SAMPLING

This paper describes the experience gained by the IAEA in the detection of undeclared nuclear material and activities in hot cells at research reactor facilities by using environmental sampling (ES). Extremely low detection limits associated with the analytical methods applied to environmental samples make concealment activities (e.g., use of portable containments) very difficult. For instance, particle analysis by Secondary Ion Mass Spectrometry (SIMS) or by Thermal Ionization Mass Spectrometry (TIMS) can detect the presence of uranium and plutonium and accurately measure the relative abundance of their isotopes in micrometer size particles isolated from cotton swipes. Other analytical techniques are used, such as, low background high resolution gamma spectrometry for the identification of gamma emitting fission and activation products, as well as Isotope Dilution Mass Spectrometry (IDMS) for the determination of U and/or Pu element concentrations and their isotope abundances. The evaluation of the resulting analytical data can allow drawing conclusions on the irradiation history of any nuclear material present and can provide concrete evidence of separation of plutonium including an estimation of the separation date. ES is implemented routinely during inspections or design information verification (DIV) activities in all types of nuclear facilities, including those with hot cells. In States that have an Additional Protocol to their safeguards agreement in force, ES may be implemented randomly and on short notice during complementary access or unannounced inspections. At a time when the IAEA is seeking greater confidence in the absence of undeclared nuclear materials and activities, the ES technique in combination with other inspection activities is proving to be effective in providing such assurance.