Interim report of performance test of the Advanced Verification for Inventory Sample System (AVIS)

This paper describes an interim summary on the results of performance test of the Advanced Verification for Inventory Sample System (AVIS). The AVIS is a safeguards system for small samples from the pellet fabrication process at the Japan Nuclear Fuel Limited (JNFL) mixed oxide fuel fabrication plant (J-MOX). The target accuracy required by IAEA is a total measurement uncertainty (TMU) for 240 Pu effective mass that is less than 0.5% in order to reduce the number of destructive assay (DA) samples. Japan Atomic Energy Agency (JAEA) has conducted the performance test by using 252 Cf neutron sources (phase 1) in order to evaluate the detector features such as the neutron detection efficiency and the die-away time. JAEA also performed the preliminary TMU evaluation of the AVIS based on the result of the phase 1 test. Based on these evaluations, JAEA concluded that the AVIS would achieve the target uncertainty for MOX samples and have an enough capability to reduce the number of DA samples. The validity of the evaluation will be confirmed by the performance test by using MOX materials (phase 2) this year.