• 분석과학
• /
• 제23권6호
• /
• pp.518-523
• /
• 2010

본 논문에서는 반응속도론적 인광 분석기(Kinetic Phosphorescence Analyzer, KPA)를 이 용하여 환경 시료 중의 우라늄 동위원소 분석에 대한 연구를 기술하였다. 극초단파 산분해 기술을 이용하여 토양 및 유리 재질 시료로부터 우라늄 성분을 추출한 후, UTEVA 수지를 통해서 우라늄 동위원소를 순수하게 분리하였고 KPA로 우라늄 농도를 정량하였다. 우라늄 표준용액을 사용하여 KPA를 이용한 우라늄 측정법에 대한 선형성 및 재현성 실험을 수행하였다. 우라늄 표준용액, 지하수 및 인증 표준시료에 대해 KPA를 사용하여 우라늄 농도를 측정하여 KPA를 이용한 우라늄 분석법에 대한 신뢰도를 검증하였다.

• Mass Spectrometry Letters
• /
• 제7권3호
• /
• pp.64-68
• /
• 2016

Scanning electron microscopy combined with thermal ionization mass spectrometry (SEM-TIMS) was used to determine the precise isotope ratios of ultra-trace levels of uranium contained in individual microparticles. An advanced multiple ion counter system consisting of three secondary ion multipliers and two compact discrete dynodes was used for complete simultaneous ion detection. For verification purposes, using TIMS with complete simultaneous measurement, isotopes were analyzed in 5 pg of uranium of a certified reference material. A microprobe in the SEM was used to transfer individual particles from a NUSIMEP-7 sample to TIMS filaments, which were then subjected to SEM-TIMS and complete simultaneous measurement. The excellent agreement in the resulting uranium isotope ratios with the certified NUSIMEP-7 values shows the validity of SEM-TIMS with complete simultaneous measurement for the analysis of uranium isotopes in individual particles. Further experimental study required for investigation of simultaneous measurement using the advanced multiple ion counter system is presented.

• Journal of Radiation Protection and Research
• /
• 제24권1호
• /
• pp.1-7
• /
• 1999

기존의 TBP 용매 추출법을 토대로 간단하고 정밀한 환경시료중 우라늄 동위원소 분석법을 개발했다. 질산-불화수소를 가해 토양시료를 분해하였고 TBP와 $CCl_4$등의 유기용매 혼합비율을 조절하여 우라늄을 수층에서 유기 층으로 추출하였으며 8 M HCl를 사용하여 토륨성분을 제거한 후 1 M HCl로 우라늄성분을 유기 층에서 수층으로 역 추출하여 우라늄만을 순수분리하였다. 기존의 전기전착 용액에 DTPA 착화제를 첨가한 새로운 전기전착 용액을 개발하여 최적의 우라늄 전착조건을 설정하였다. 수립된 우라늄 동위원소 분석법을 IAEA Reference 시료에 적용하여 개발된 분석법에 대한 신뢰성을 검증하였다.

• Journal of Radiation Protection and Research
• /
• 제26권1호
• /
• pp.1-6
• /
• 2001

방사성 동위원소에 오염된 토양시료에 대하여 정확하고 신속한 U 등위원소 분석법을 개발하였고 IAEA 표준시료에 적용하여 분석법의 타당성을 검증하였다. TBP 용매추출법의 단점을 보완하기 위해서 토양시료를 질산 및 불산을 사용하여 메트릭스 성분으로부터 우라늄을 완벽하게 추출하였고 이온교환수지와 TRU Spec 수지를 이용하여 우라늄 등위원소를 악티나이드 원소로부터 순수분리하였다. 크로마토 그래피 추출법을 사용하여 토양시료에서 우라늄 등위원소 화학수율은 TBP 용매추출법의 경우보다 10% 정도 증가하였다. 크로마토 그래피 추출법을 사용한 IAEA 토양시료에 분석결과는 IAEA에서 보고된 수치와 일치하였다.

• 분석과학
• /
• 제31권3호
• /
• pp.134-142
• /
• 2018

The uranium isotopic ratio in environmental samples around nuclear facilities is important because it reveals information regarding illegal activities or anthropogenic pollution. Determination of uranium isotopes, however, is a challenging task requiring much labor and time because of the complex separation procedures and lengthy process. In this study, a rapid determination method for uranium isotopes in environmental samples was developed using. The sample was completely decomposed using the alkali fusion method. The separation procedure using extraction chromatography (UTEVA) was simplified in a single step without any further removal process for Si and major matrix elements. The established method can be completed within 3 h from sample dissolution to ICP-MS measurement. Most matrix elements and uranium isotopes in the soil samples were well separated and purified. Five types of were used to assess the method's accuracy and precision for a rapid uranium analysis method. The analytical accuracy for all CRM samples ranged from 95.1 % to 97.8 %, and the relative standard deviation was below 3.9 %. From the analytical results, one may draw conclusions that the evaluated method for uranium isotopes using alkali-fusion, the extraction chromatography process, and ICP-MS measurements is fast and fairly reliable owing to its recovering efficiencies. Thus, it is expected that the evaluated method can contribute to the improvement of environmental monitoring ability.

• Nuclear Engineering and Technology
• /
• 제52권12호
• /
• pp.2867-2873
• /
• 2020

In reprocessed uranium, derived from an impoverished fuel of light-water moderated reactors, there are isotopes of ^{232, 234, 236}U, which make its recycling remarkably difficult. A method of concentration of ²³⁵U target isotope in cascade's additional product was proposed to recover the isotopic composition of reprocessed uranium. A general calculation procedure is presented and a parameters' optimization of multi-flow cascades with additional products. For the first time a numeric model of a cascade that uses the cuts of partial flows of stages with relatively high separation factors was applied in this procedure. A novel computing experiment is carried out on separation of reprocessed uranium hexafluoride with providing a high concentration of ²³⁵U in cascade's additional product with subsequent dilution. The parameters of cascades' stages are determined so as to allow reducing the ^{232, 234, 236}U isotope content up to the acceptable. It was demonstrated that the dilution of selected products by the natural waste makes it possible to receive a low enriched uranium hexafluoride that meets the ASTM C996-15 specification for commercial grade.

• Nuclear Engineering and Technology
• /
• 제54권10호
• /
• pp.3650-3659
• /
• 2022

We proposed a modification of a double cascade scheme to enrich reprocessed uranium. Such a cascade scheme represents a combination of one cascade with "broadening" of the flow and an ordinary three-flow cascade. A calculation and optimization method has been developed for the proposed scheme according to various efficiency criteria. It is shown that the proposed scheme makes it possible to obtain low-enriched uranium of commercial quality using reprocessed uranium of different initial compositions. For example, the enrichment of reprocessed uranium, which had gone through five consequent recycles, was considered. The proposed scheme allowed to enrich it with simultaneous fulfillment of restrictions on isotopes ²³²U, ²³⁴U, and ²³⁶U. Such results indicate the scheme's applicability under conditions of multiple recycling of uranium in reactor fuel. Computational experiments have shown that in the proposed modification, a noticeable saving of natural uranium in the cycle (~18%) can be achieved, provided that the additional consumption of separative work does not exceed 10%, compared with the case of enrichment of natural uranium to obtain LEU of equivalent quality.

• 한국수소및신에너지학회논문집
• /
• 제27권1호
• /
• pp.22-28
• /
• 2016

It is necessary to store and supply hydrogen isotopes for Tokamak operation. A storage and delivery system (SDS) is used for storing hydrogen isotopes as a metal hydride form. We designed and fabricated a depleted uranium (DU) bed to store hydrogen isotopes. The rapid storage of hydrogen isotopes is very important not only for safety reasons but also for the economic design and operation of the SDS. The delivery rate at the desorption temperatures without the operation of a dry pump was analyzed in comparison with that with the operation of the dry pump. The effect of the initial desorption temperatures on the dehydriding of the DU without the operation of the dry pump was measured. The effect of the initial desorption temperatures on the dehydriding of DU with the operation of the dry pump was also measured and analyzed. The primary pressure on the desorption temperatures without the operation of the dry pump was analyzed in comparison with that with the operation of the dry pump. The temperature gradient of the coil heater and the primary vessel was also analyzed. Our results will be used to develop pilot scale hydrogen isotope processes. It was confirmed that dehydriding of a medium-scale DU bed has enabled without the operation of the dry pump.

• Mass Spectrometry Letters
• /
• 제3권2호
• /
• pp.54-57
• /
• 2012

Mass spectrometric analysis was carried out using multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) for the precise and accurate determination of the isotope ratios of ultratrace levels of uranium dissolved in 3% $HNO_3$. We used the certified reference material (CRM) 112-A at a trace level of 100 pg/mL for the uranium isotopic measurement. Multiple collectors were utilized for the simultaneous measurement of uranium isotopes to reduce the signal uncertainty due to variations in the ion beam intensity over time. Mass bias correction was applied to the measured U isotopes to improve the precision and accuracy. Furthermore, elemental standard solution with certified values of platinum, iridium, gold, and thallium dissolved in 3% $HNO_3$ were analyzed to investigate the formation rates of the polyatomic ions of $Ir^{40}$ $Ar^+$, $Pt^{40}$ $Ar^+$, $Tl^{40}$ $Ar^+$, $Au^{40}$ $Ar^+$ for the concentration range of 50-400 pg/mL. Those polyatomic ions have mass-to-charge ratios in the 230-245 m/z region that it would contribute to the increase of background intensity of uranium, thorium, plutonium, and americium isotopes. The effect of the polyatomic ion interference on uranium isotope measurement has been estimated.

• Bulletin of the Korean Chemical Society
• /
• 제32권12호
• /
• pp.4327-4331
• /
• 2011

A new method in thermal ionization mass spectrometry (TIMS) was developed to correct peak tailing backgrounds in the isotope ratio measurements of uranium in ultra trace levels for higher accuracy. Two different uranium standard reference materials (U005 and U030) were used to construct databases of signal intensities at mass 234 u and mass 236 u, which correspond to the two uranium minor isotopes, and signal intensity of $^{238}U$. Correlations between peak tailing backgrounds and $^{238}U$ were obtained by least-squares regression on calculated backgrounds at mass 234 u and mass 236 u with respect to the signal intensity of $^{238}U$ followed by separation of the peak tails of the two major isotopes of uranium ($^{235}U$ and $^{238}U$), which enables us to obtain a master equation for peak tailing background correction on all kinds of samples. Verification of the correction method was carried out using U010 and IRMM-040a.