HA-AWCC Instrumental test prior hot commissioning for characterisation of U- residue from 99Mo production process in Republic of South Africa.

99Mo is produced by the irradiation of high and low-enriched uranium (HEU and LEU) resulting in the accumulation of large quantities of uranium residues. The 235U content of these uranium residues (U-residue) must be characterized or quantified for International Atomic Energy Agency (IAEA) safeguards purposes. Conventional neutron counting techniques such as Active Well Coincidence Counting (AWCC) are incapable of quantifying the 235U content of the U-residue due to high level of radiation emitted and potentially moisture present. In 2010, the High Activity Active Well Coincidence Counter (HA-AWCC) was designed and developed by Non-Destructive Assay (NDA) experts from Oak Ridge National Laboratory (ORNL, USA), The South African Nuclear Energy Corporation SOC Limited ( NECSA, RSA) and (IAEA) with the purpose of quantifying the 235U content in the U-residue. In this work, the set-up of the HA-AWCC instrument as well as its behavior during the hot commissioning pre- test activities will be discussed. The HA-AWCC tests included background measurements, neutron counting measurements with Californium (252Cf) sources of activities 11.5 and 30 µCi, high voltage plateau measurements as well as a cold canister run.