Assulin Maor, Yam Ruth, Grego-Shnaiderman Alina, Eretz Kdosha Yizhaq, Lulu-Bitton Noa, Elish Eyal, Shemesh Aldo
Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
Analytical Chemistry Department, Nuclear Research Center Negev (NRCN), Beer Sheva 84190, Israel.
ACS Omega. 2023 Sep 5;8(37):33651-33657. doi: 10.1021/acsomega.3c03903. eCollection 2023 Sep 19.
The fabrication of UO from UO is an essential reaction in the nuclear fuel cycle. The oxygen isotope fractionation associated with this reaction has significant implications in the general field of nuclear forensics. Hence, the oxygen isotope fractionation during the reduction of UO to UO was determined in the temperature range of 500-700 °C and for a duration of 2 to 6 h under a high-purity H atmosphere. Three UO samples, possessing a different oxygen isotopic composition, were used to investigate key parameters involved with the fractionation during the reduction process. All UO products did not maintain the original isotope composition of the starting UO under all conditions. The results show that the system UO-HO attains isotope equilibrium at 600 °C, provided the reduction process lasts at least 4 h or more. At 600 °C, UO was isotopically depleted by 2.89 ± 0.82‰ compared to the UO from which it was produced. We find that the HO formed during the reduction plays a major role in determining the final δO of UO prepared from UO The isotope equilibrium of the system UO-HO at 600 °C was calculated, indicating that δO of the HO was enriched by about 11‰ relative to the UO due to the uranium mass effect. These findings could potentially have important implications for nuclear forensics, as they provide a new method for determining the history of UO samples and tracing back their production process.
从UO制备UO是核燃料循环中的一个重要反应。与该反应相关的氧同位素分馏在核取证的一般领域具有重要意义。因此，在500 - 700°C的温度范围内，于高纯H气氛下持续2至6小时，测定了UO还原为UO过程中的氧同位素分馏。使用了三个具有不同氧同位素组成的UO样品来研究还原过程中与分馏相关的关键参数。在所有条件下，所有UO产物均未保持起始UO的原始同位素组成。结果表明，若还原过程持续至少4小时或更长时间，UO - HO体系在600°C时达到同位素平衡。在600°C时，与生成它的UO相比，UO的同位素贫化了2.89±0.82‰。我们发现还原过程中形成的HO在决定由UO制备的UO的最终δO方面起主要作用。计算了UO - HO体系在600°C时的同位素平衡，表明由于铀质量效应，HO的δO相对于UO富集了约11‰。这些发现可能对核取证具有重要意义，因为它们提供了一种确定UO样品历史并追溯其生产过程的新方法。
