Developments in IAEA Non-Destructive Assay of Nuclear Materials and Facilities

Non Destructive Assay (NDA) measurement techniques play a central role in the verification of nuclear material placed under safeguards. In recent years, the International Atomic Energy Agency (“The Agency”) has promoted the development and implementation of several new or improved technologies in order to face international safeguards challenges. This article describes some of these developments and how they will allow the Agency to meet its strategic objective of providing improved detection capabilities for nuclear material verification. The presentation describes several examples of field applications of NDA instruments, illustrating recent improvements in the Agency's detection capabilities. The paper discusses a measurement campaign performed in the spent fuel pond of a reprocessing plant utilizing the underwater Safeguards Mox Python (SMOPY) device for spent fuel verification. This work led to an ability to successfully re-establish continuity of knowledge in respect of MOX Material Test Reactor (MTR) fuels, which was achieved through discriminating between irradiated MOX fuel assemblies and LEU assemblies with the combined gamma and neutron detection capabilities of the SMOPY device. This presentation also describes some work performed in the field with a high-resolution gamma ray spectrometry system coupled with absolute efficiency calibrations generated by the In-Situ Object Counting Software (ISOCS). This approach permitted the partial defect verification of natural, LEU and HEU fresh fuel pins thus extending the range of verifications currently performed by Active Well Coincidence Counter (AWCC) measurements. The presentation also addresses developments in the use of Monte Carlo (MCNP-5) techniques for establishing and validating the calibration curves of gamma detectors in order to perform the quantitative verification 235U of MTR fresh fuels and CANDU fuel pellets. As a result of the support of the EC Joint Research Centre (JRC) at Ispra, Italy, which delivered the MCNP-PTA code and validated models of NDA instruments, the Agency is now able to produce and validate the calibration curves applicable to all neutron coincidence-counting instruments used within the Department of Safeguards. The presentation concludes with a description of a non-nuclear based NDA technique, ground penetrating radar systems, which present a significant opportunity to improve substantially the Agency's capabilities in the verification of facility design information.