The Impact of 234U α-emission Induced Radiolysis on UF6 Storage Composition for Non-destructive Verification via Passive Neutron Counting

Byrne, S. and Favalli, A. and Croft, S. (2024) The Impact of 234U α-emission Induced Radiolysis on UF6 Storage Composition for Non-destructive Verification via Passive Neutron Counting. ESARDA Bulletin, 66. pp. 28-34. ISSN 0392-3029

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Abstract

The mass of 235 U present in storage cylinders containing low enriched uranium (LEU) in the form of uranium hexafluoride (UF 6) may be verified nondestructively using a combination of gamma-ray based enrichment meter and passive neutron counting techniques. A hypothetical concern is that the (α,n) production rate in aged bulk UF 6 might differ from that of fresh material if the chemical composition changes over time, the thought being that this could be initiated by the self-induced radiation field, the process known as radiolysis. To support the physics-based interpretation of the observations Croft et al. measured, in 2020, for the specific 234 U-driven (α,n)-yield in UF 6, this work reviews available literature to quantify the possible impact of radiolysis on (α,n) production rate. Building on the review, a radiochemical yield value, G = 0.5 molecules of F 2 per 100 eV is selected, to calculate the impact of UF5 production – via radiolysis – on the (α,n)-yield. Calculations demonstrate a negligible impact on bulk UF 6 concentration and respective neutron yield.