Performance test results of the advanced verification for inventory sample system (AVIS) (2)

The Advanced Verification for Inventory sample System (AVIS) is a nondestructive assay (NDA) system to verify the plutonium mass with high accuracy in the small plutonium uranium mixed oxide (MOX) powder and pellet samples at Japan Nuclear Fuel Limited MOX fuel fabrication plant (J-MOX) under construction. The AVIS was designed by Los Alamos National Laboratory (LANL) under the auspices of the Secretariat of Nuclear Regulation Authority. The AVIS will fulfill an important role in the safeguards approach for J-MOX because the AVIS will be used as a verification tool instead of destructive analysis for a part of the samples for bias defect. Japan Atomic Energy Agency (JAEA), which has experience and knowledge to develop the NDA systems and plutonium handling fields, was entrusted with performance testing for the AVIS by the Nuclear Material Control Center of Japan. As a first phase, JAEA conducted the performance tests by using ²⁵²Cf neutron sources. In this test, neutron detection efficiency, die-away time and other detector properties were evaluated, and it was confirmed that the AVIS had the performance designed by LANL. As a second phase, JAEA conducted the performance tests by using MOX samples. In this test, the measurement accuracy of the AVIS was evaluated. From the results, it was confirmed that the AVIS could almost satisfy the performance requirements on the accuracy by IAEA. (author)