• Nuclear Engineering and Technology
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• 제47권7호
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• pp.924-933
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• 2015

The correlation of the isotopic composition of uranium, plutonium, neodymium, and cesium with the burnup for high burnup pressurized water reactor fuels irradiated in nuclear power reactors has been experimentally investigated. The total burnup was determined by Nd-148 and the fractional $^{235}U$ burnup was determined by U and Pu mass spectrometric methods. The isotopic compositions of U, Pu, Nd, and Cs after their separation from the irradiated fuel samples were measured using thermal ionization mass spectrometry. The contents of these elements in the irradiated fuel were determined through an isotope dilution mass spectrometric method using $^{233}U$, $^{242}Pu$, $^{150}Nd$, and $^{133}Cs$ as spikes. The activity ratios of Cs isotopes in the fuel samples were determined using gamma-ray spectrometry. The content of each element and its isotopic compositions in the irradiated fuel were expressed by their correlation with the total and fractional burnup, burnup parameters, and the isotopic compositions of different elements. The results obtained from the experimental methods were compared with those calculated using the ORIGEN-S code.

• 자원환경지질
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• 제56권5호
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• pp.557-564
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• 2023

우라늄 등의 핵물질은 원자력 발전의 연료로 사용되지만, 비평화적 용도로 전용될 가능성이 커서 이에 대한 국제적인 사찰과 규제가 이루어지고 있다. 핵물질 사용 시설에서 확보한 미세 입자상 물질의 동위원소 분석 자료는 핵물질의 기원 및 농축 방법등에 대한 중요한 정보를 제공할 수 있어 핵 안전 및 핵 사찰 분야에서 널리 활용되고 있다. 이번 연구에서는 국내 최초로 국내에 설치된 대형 이차이온 질량분석기를 활용해 미세 입자 시료에 대한 우라늄 동위원소를 측정한 결과를 소개한다. U-200 표준물질을 사용해 미세 입자의 위치를 확인하고 고정밀 정밀분석을 통해 오차범위내에서 표준값과 일치하는 결과를 얻을 수 있었다.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.275-279
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• 2001

In uranium enrichment plants and nuclear fuel fabrication facilities, exact measurement of fissile isotope enrichment of uranium is required for material accounting in international safeguards inspection as well as process quality control. The purpose of this study was to develop a simple measurement system which can portably be used at nuclear fuel fabrication plants especially dealing with low enriched uranium. For this purpose, a small size CZT (CdZnTe) detector was used, and the detector performance in low uranium gamma/X -rays energy range was investigated by use of various enriched uranium oxide samples. New enrichment measurement technique and analysis method for low enriched uranium oxide, so-called, 'semi-peak ratio technique' was developed. The newly developed method was considered as an alternative technique for the low enrichment and would be useful to account nuclear material in safeguarding activity at nuclear fuel fabrication facility.

• Journal of Radiation Protection and Research
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• 제35권3호
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• pp.105-110
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• 2010

고순도 반도체 감마분광시스템을 이용하여 토양 시료를 파괴하지 않고 화학 전처리 단계가 필요없는 우라늄 방사능 분석 기술을 개발하였다. 본 논문에서 제시한 방법을 이용한 분석결과와 기존에 일반적으로 사용하는 알파분광분석법(Alpha Spectrometry)의 결과를 비교하였다. 비교결과 불확도 범위 내에서 비슷한 측정값을 보였다. 따라서 본 논문에서 제시한 방법은 토양시료의 우라늄 분석에 이용될 수 있을 것이다.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.613-623
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• 2016

Molybdenum-99 ($^{99}Mo$) is the most important isotope because its daughter isotope, technetium-99m ($^{99m}Tc$), has been the most widely used medical radioisotope for more than 50 years, accounting for > 80% of total nuclear diagnostics worldwide. In this review, radiochemical routes for the production of $^{99}Mo$, and the aspects for selecting a suitable process strategy are discussed from the historical viewpoint of $^{99}Mo$ technology developments. Most of the industrial-scale $^{99}Mo$ processes have been based on the fission of $^{235}U$. Recently, important issues have been raised for the conversion of fission $^{99}Mo$ targets from highly enriched uranium to low enriched uranium (LEU). The development of new LEU targets with higher density was requested to compensate for the loss of $^{99}Mo$ yield, caused by a significant reduction of $^{235}U$ enrichment, from the conversion. As the dramatic increment of intermediate level liquid waste is also expected from the conversion, an effective strategy to reduce the waste generation from the fission $^{99}Mo$ production is required. The mitigation of radioxenon emission from medical radioisotope production facilities is discussed in relation with the monitoring of nuclear explosions and comprehensive nuclear test ban. Lastly, the $^{99}Mo$ production process paired with the Korea Atomic Energy Research Institute's own LEU target is proposed as one of the most suitable processes for the LEU target.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.608-609
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• 2018

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
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• pp.67-68
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• 2017

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.551-556
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• 1998

The correlation of isotope composition of Zr with the turnup and some heavy isotopes in PWR uranium dioxide fuel has been investigated. The total and partial ($^{235}$ U) burnup were determined by $^{148Nd}$ and by U and Pu mass spectrometric method, respectively. After separating Zr from the fuel samples, its isotope composition was measured by mass spectrometry. In addition, the quantities of the U and Pu in the spent fuel were determined by isotope di lution mass spectrometric method using $^{233}$ U and $^{242}$ Pu as spikes. The content of some heavy isotopes, $^{235}$ U, $^{239}$ Pu and $^{241}$ Pu, and the Pu Contribution to total turnup were expressed by the correlation with Zr isotope ratios, $^{91}$ Zr/$^{96}$ Zr and $^{93}$ Zr/$^{96}$ Zr The correlations by isotope compositions measured were compared wi th those calculated from ORIGEN2 code.

• 방사선산업학회지
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• 제17권4호
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• pp.457-469
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• 2023

The clearance level by nuclide is announced by the Nuclear Safety and Security Commission. However, the clearance level of uranium existing in nature has not been announced, and research is needed. Therefore, the purpose of this study was to evaluate the clearance level of uranium nuclides appropriate to domestic conditions preliminary. For this purpose, this study selected major processes for recycling metal wastes and analyzed the exposure scenarios and major input factors by investigating the characteristics of each process. Then, the radiation dose to the general public and workers was evaluated according to the selected scenarios. Finally, the results of the radiation dose per unit radioactivity for each scenario were analyzed to derive the clearance level of uranium in metal waste. The results of the radiation dose assessment for both the general public and workers per unit radioactivity of uranium isotopes were shown to meet the allowable dose (individual dose of 10 µSv y^-1 and collective dose of 1 Man-Sv y^-1) regulated by the Nuclear Safety and Security Commission. The most conservative scenarios for volumetric and surface contamination were evaluated for the handling of the slag generated after the melting of the metal waste and the direct reuse of the contaminated metal waste into the building without further disposal. For each of these scenarios, the radioactivity concentration by uranium isotope was calculated, and the clearance level of uranium in metal waste was calculated through the radioactivity ratio by enrichment. The results of this study can be used as a basic data for defining the clearance level of uranium-contaminated radioactive waste.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3913-3923
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• 2023

Todays, medium energy resolution detectors are preferably used in radioisotope identification devices(RID) in nuclear and radioactive material categorization. However, there is still a need to develop or enhance « automated identifiers » for the useful RID algorithms. To decide whether any material is SNM or NORM, a key parameter is the better energy resolution of the detector. Although masking, shielding and gain shift/stabilization and other affecting parameters on site are also important for successful operations, the suitability of the RID algorithm is also a critical point to enhance the identification reliability while extracting the features from the spectral analysis. In this study, a RID algorithm based on Bayesian statistical method has been modified for medium energy resolution detectors and applied to the uranium gamma-ray spectra taken by a LaBr3:Ce detector. The present Bayesian RID algorithm covers up to 2000 keV energy range. It uses the peak centroids, the peak areas from the measured gamma-ray spectra. The extraction features are derived from the peak-based Bayesian classifiers to estimate a posterior probability for each isotope in the ANSI library. The program operations were tested under a MATLAB platform. The present peak based Bayesian RID algorithm was validated by using single isotopes(²⁴¹Am, ⁵⁷Co, ¹³⁷Cs, ⁵⁴Mn, ⁶⁰Co), and then applied to five standard nuclear materials(0.32-4.51% at.²³⁵U), as well as natural U- and Th-ores. The ID performance of the RID algorithm was quantified in terms of F-score for each isotope. The posterior probability is calculated to be 54.5-74.4% for ²³⁸U and 4.7-10.5% for ²³⁵U in EC-NRM171 uranium materials. For the case of the more complex gamma-ray spectra from CRMs, the total scoring (ST) method was preferred for its ID performance evaluation. It was shown that the present peak based Bayesian RID algorithm can be applied to identify ²³⁵U and ²³⁸U isotopes in LEU or natural U-Th samples if a medium energy resolution detector is was in the measurements.