• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 춘계학술발표회요약집
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• pp.353-353
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• 1999

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.328.1-328
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• 1999

• 방사성폐기물학회지
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• 제4권2호
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• pp.179-186
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• 2006

원자력을 이용하는 시설 및 그와 관련한 연구개발실험실로부터 각종 화학폐수가 다량으로 발생되고 있으며 이들 폐수를 화학폐수 전용처리시설로 처리하고 있으나 최종 건조 케이크내에 함유된 우라늄의 농도가 규제면제농도인 10 Bq/g을 약간 초과하므로서 방사성폐기물로 분류하여 별도로 저장하고 있다. 화학폐수 처리후 침전된 슬러지내의 우라늄 농도를 분석한 결과 우라늄이 용액상이 아닌 침전물상에 존재함을 알았으며, 이들 우라늄을 침전물로부터 용액상으로 용해하기 위하여 강질산으로 용해시켰다. 그 결과 대부분의 우라늄이 슬러지의 침전물로부터 용액상으로 용출되었으며, 용해후 얻어진 슬러지 산용해액에 대해 IRN-77과 비드형으로 새로 제조한 다이포실 수지를 실 폐액처리에 적용하기 위한 흡착실험을 수행하였다. IRN-77과 다이포실 비드를 단독, 혼합 또는 단계적으로 사용한 결과, 80%이상의 우라늄 흡착효율을 얻기 위해서는 산용해액과 동등량 또는 그 이상의 다량의 수지가 소요되었다. 한편 침전 슬러지를 압착하여 부피가 더욱 축소된 탈수케이크를 산용해한 결과, 탈수케이크 대 질산의 비율이 3:2에서 우라늄의 함량을 최대 11 mg/L을 얻었으며 슬러지 용해시보다 적은 양으로 산용해가 가능하였다. 탈수 케이크 산용해액의 방사능 농도는 6.97E-01 Bq/ml 로서 기존의 자연증발처리시설에서 처리가 가능한 수준이었으며, 건조케이크의 비방사능은 11.2 Bq/g로서 최종 폐기물로 발생될 폐증발천의 비방사능이 4.3 Bq/g으로 평가되어 우라늄 동위원소의 규제면제치인 10 Bq/g 미만이므로 자체처분이 가능한 수준이었다. 결론적으로 화학폐수를 처리한 후 부피가 최소화된 탈수케이크에서 우라늄을 산용해시키고 최종 산용해액은 기존의 자연증발시설로 증발처리하면 방사성 건조케이크의 발생 없이 또한 자연증발천도 자체처분이 가능한 최적의 방안을 도출하였다.

• 분석과학
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• 제25권2호
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• pp.146-151
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• 2012

액체섬광계수기를 이용한 지하수 내 우라늄 동위원소의 최적 측정방법에 대한 연구를 수행하였다. 용매추출법을 이용해 우라늄을 추출하였고, 시료량과 pH에 따른 추출효율을 조사하였다. 우라늄 추출효율에 미치는 영향을 조사하기 위해 표준용액을 사용하여 100 mL~1 L 범위에서 시료량을 변화 시켰으며 pH는 0.5~10 범위에서 측정하였다. 실험결과 우라늄의 추출효율은 pH에 매우 민감한 것으로 나타났으며 pH 2 에서 최고치를 나타냈다. 이에 반해 시료량은 추출효율에 큰 영향을 미치지 않는 것으로 나타났다. 우라늄 표준시료를 이용한 실험 결과 추출효율은 $95.93{\pm}0.77%$ 이었고, 계측시간 5시간을 기준으로 한 우라늄의 검출한계는 0.018 Bq/L 이었다. 본 연구결과로부터 지하수에 함유된 우라늄의 최적추출 및 측정법을 확립할 수 있었고 본 방법의 검증을 위해서 지하수 중 우라늄의 분석에 일반적으로 사용되는 ICP-MS 측정결과와의 비교분석도 함께 수행하였다. 본 연구에서 개발된 분석법을 대전 주변 지역 네 곳의 지하수를 대상으로 우라늄 함량 및 동위원소 비의 측정에 적용한 결과 우라늄의 농도는 0.59~6.69 Bq/L 그리고 $^{234}U/^{238}U$의 방사성 비는 0.88~1.40 범위로 나타내었다.

• Journal of Radiation Protection and Research
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• 제43권3호
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• pp.120-123
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• 2018

Background: Analysis of enrichment of $UO_2$ is important to verify the information declared by the license-holders. The redundancy methods are required to guarantee the analysis result. Korea Institute of Nuclear Nonproliferation and Control (KINAC) used to analyze it with alpha spectrometry and consign to Korea Basic Science Institute (KBSI) Thermal Ionization Mass Spectrometry (TIMS). This article evaluated the similarity of the results with two methods and derive correlation equation. It could be compared to the results measured by TIMS running by KBSI. Materials and Methods: There are not many certified materials for the uranium enrichment value. Therefore, 34 uranium pellets, which have the wide range of uranium enrichment from 0.21 to 4.69 wt%, were used for the experiments by the alpha spectrometry and the TIMS. Results and Discussion: The study shows there are the tendency of analyzed enrichment by each equipment. It shows uranium enrichment with alpha spectrometry evaluated 17% higher than that with TIMS on average. The regression equations were also derived in case the similarity between the two results with two methods is lower than predicted. Two experiments were designed to compare the effect of number of samples. The $R^2$ was 0.9977 with 34 pellets. It shows the equation is appropriate to predict the enrichment values by TIMS with that of alpha spectrometry. The $R^2$ was 0.9858 with four pellets for ten times. The $R^2$ decreased while the number of samples increased. The discrepancy between the lowest and highest enrichment seems to be one of the reason for it. Conclusion: KINAC expects the first equation with 34 samples is useful to predict the result with TIMS, the redundancy method, based on the alpha spectrometry. The extra samples are necessary to collect if the enrichment value analyzed by TIMS is lower than the value predicted with the equation. Further study would be followed related to the impact of the peak counts for each uranium isotopes, sample amount and number of experiments when TIMS established in KINAC by the end of 2018.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.378-390
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• 2023

The SPES (Selective Production of Exotic Species) facility, currently under development at Legnaro National Laboratories of INFN, aims at the production of intense RIB (Radioactive Ion Beams) employing the Isotope Separation On-Line (ISOL) technique for interdisciplinary research. The radioactive isotopes of interest are produced by the interaction of a multi-foil uranium carbide target with a 40 MeV 200 μA proton beam generated by a cyclotron proton driver. The Target Ion Source (TIS) is the core of the SPES project, here the radioactive nuclei, mainly neutron-rich isotopes, are stopped, extracted, ionized, separated, accelerated and delivered to specific experimental areas. Due to efficiency reasons, the TIS unit needs to be replaced periodically during operation. In this highly radioactive environment, the employment of autonomous systems allows the manipulation, transport, and storage of the TIS unit without the need for human intervention. A dedicated remote handling infrastructure is therefore under development to fulfill the functional and safety requirement of the project. This contribution describes the layout of the SPES target area, where all the remote handling systems operate to grant the smooth operation of the facility avoiding personnel exposure to a high dose rate or contamination issues.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.601-610
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• 2024

This paper gives an extensive analysis on the characterization of xenon isotopic ratios for various nuclear reactors and nuclear explosions through neutronic depletion codes. The results of the characterization can be used for discriminating the sources of the xenon isotopes' release among the nuclear explosions and nuclear reactors. The considered sources of the xenon radionuclides do not only include PWR, CANDU, and nuclear explosions using uranium and plutonium bombs, but also IRT-200 and 5MWe Yongbyon (MAGNOX reactor) research reactors operated in North Korea. A new data base (DB) on xenon isotopic activity ratios was produced using the results of the characterization, which can be used in discrimination of the sources of xenon isotopes. The results of the study show that 5MWe Yongbyon reactor has quite different characteristics in ¹³⁵Xe/¹³³Xe ratio from the PWRs and the nuclear reactors have different characteristics in ¹³⁵Xe/¹³³Xe ratios from the nuclear explosions.

• 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.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2830-2838
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• 2021

This work deals with the assessment of the burnup capabilities of the Serpent Monte Carlo code to predict spent nuclear fuel (SNF) isotopic concentrations for low-enriched uranium (LEU) fuel at different burnup levels up to 47 MWd/kgU. The irradiation of six UO₂ experimental samples in three different VVER-1000 reactor units has been simulated and the predicted concentrations of actinides up to ²⁴⁴Cm have been compared with the corresponding measured values. The results show a global good agreement between calculated and experimental concentrations, in several cases within the margins of the nuclear data uncertainties and in a few cases even within the reported experimental uncertainties. The differences in the performances of the JEFF3.1.1, ENDF/B-VII.1 and ENDF/B-VIII.0 nuclear data libraries (NDLs) have also been assessed and the use of the newly released ENDF/B-VIII.0 library has shown an increased accuracy in the prediction of the C/E's for some of the actinides considered, particularly for the plutonium isotopes. This work represents a step forward towards the validation of advanced simulation tools against post irradiation experimental data and the obtained results provide an evidence of the capabilities of the Serpent Monte-Carlo code with the associated modern NDLs to accurately compute SNF nuclide inventory concentrations for VVER-1000 type reactors.

• 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.