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Oxygen Isotopic Composition of U3O8 Synthesized From U Metal, Uranyl Nitrate Hydrate, and UO3 as a Signature for Nuclear Forensics
ACS Omega ( IF 3.7 ) Pub Date : 2022-02-22 , DOI: 10.1021/acsomega.1c07042
Maor Assulin 1, 2 , Ruth Yam 1 , Eyal Elish 2 , Aldo Shemesh 1
Affiliation  

Triuranium octoxide (U3O8) is one of the main compounds in the nuclear fuel cycle. As such, identifying its processing parameters that control the oxygen isotopic composition could be developed as a new signature for nuclear forensic investigation. This study investigated the effect of different synthesis conditions such as calcination time, temperature, and cooling rates on the final δ18O values of U3O8, produced from uranium metal, uranyl nitrate hydrate, and uranium trioxide as starting materials. The results showed that δ18O of U3O8 is independent of the above-listed starting materials. δ18O values of 10 synthetic U3O8 were similar (9.35 ± 0.46‰) and did not change as a function of calcination time or calcination temperature. We showed that the cooling rate of U3O8 at the end of the synthesis process determines the final oxygen isotope composition, yielding a significant isotope effect on the order of 30‰. Experiments with two isotopically spiked 10 M HNO3, with a difference of δ18O ∼75‰, show that no memory of the starting solution oxygen isotope signature is expressed in the final U3O8 product. We suggest that the interaction with atmospheric oxygen is the main process parameter that controls the δ18O value in U3O8. The uranium mass effect, the tendency of uranium ions to preferentially incorporate 16O, is expressed during the solid–gas oxygen exchange, which occurs throughout cooling of the system.

中文翻译:

由 U 金属、硝酸铀酰水合物和 UO3 合成的 U3O8 的氧同位素组成作为核法医学的特征

三氧化铀 (U 3 O 8 ) 是核燃料循环中的主要化合物之一。因此,确定控制氧同位素组成的工艺参数可以作为核法证调查的新标志。本研究调查了不同合成条件(例如煅烧时间、温度和冷却速率)对以金属铀、硝酸铀酰水合物和三氧化铀为原料生产的 U 3 O 8的最终 δ 18 O 值的影响。结果表明,U 3 O 8的δ 18 O与上述起始原料无关。δ 1810 合成U 3 O 8的O 值相似(9.35 ± 0.46‰)并且不随煅烧时间或煅烧温度而变化。我们表明,合成过程结束时 U 3 O 8的冷却速率决定了最终的氧同位素组成,产生了 30‰ 左右的显着同位素效应。用两个同位素加标的 10 M HNO 3进行的实验表明,在最终的 U 3 O 8产品中没有表达对起始溶液氧同位素特征的记忆,差异为 δ 18 O ∼75‰ 。我们认为与大气氧的相互作用是控制 δ18 的主要过程参数U 3 O 8中的 O 值。铀质量效应,即铀离子优先结合16 O的趋势,在整个系统冷却过程中发生的固-气氧交换过程中表现出来。
更新日期:2022-02-22
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