Speaker
Description
HA-AWCC Instrumental Test Prior Hot Commissioning for Characterisation of U-residue from 99Mo Production Process in the Republic of South Africa.
TM Leshilo1, R Chauke1, PP Magampa1, HM Bohlolo 1, JA Chapman 2, RD McElroy 2
1. South African Nuclear Energy Corporation, Pretoria, South Africa.
2. Oak Ridge National Laboratory, Oak Ridge, USA
Abstract
99Mo is produced by the irradiation of high and low-enriched uranium (HEU and LEU) resulting in uranium residues accumulation as waste from 99Mo production process. These residues are highly radioactive with surface exposure rates of up to 100 R/h and is stored in stainless steel canisters. The 235U content of these uranium residues must be characterized or quantified for State and 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 moisture that might be present. In 2010 the High Activity-Active Well Coincidence Counter (HA-AWCC) was designed and developed by Non-Destructive Assay 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 activites 11.5 and 30 µCI, high voltage plateau measurements as well as a cold canister run. This work will provide a critical role in the characterization and quantification of safeguarded U-residue material by the State Safeguards Authority.
Key Words: HA-AWCC, U-residue, 235U content, pre-test activities
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