• 분석과학
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• 제13권6호
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• pp.743-750
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• 2000

라듐 및 라돈과 같은 환경 방사성 핵종의 분석 방법 중 HPGe 검출기를 이용한 감마선 분광 분석법은 대부분 플라스틱 용기를 많이 이용하고 있다. 그러나 플라스틱 용기는 대기 중 라돈 딸 핵종의 흡착에 의해 백그라운드가 증가할 뿐만 아니라 방사 평형 과정에서 생성된 기체 상의 라돈의 손실에 의하여 완전한 방사 평형에 도달하지 않는다는 것이다. 이러한 문제점을 해결하기 위하여 알루미늄 재질의 측정 용기를 제작하였고, 그 특성을 조사하였다. 알루미늄 용기를 이용하여 방사 평형 과정을 조사한 결과, 고체 및 액체 시료 모두 기체 상태의 라돈 손실 없이 라듐과 그 딸핵종들이 측정 용기 안에서 완전한 방사 평형에 도달하는 것을 알았다. 또한 감마선 분광 분석법을 이용한 고체 및 액체 시료 중의 라듐 및 라돈의 비파괴 분석이 가능함을 확인하였다.

• 방사성폐기물학회지
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• 제20권2호
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• pp.171-183
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• 2022

The parent and daughter nuclides in a radioactive decay chain arrive at secular equilibrium once they have a large half-life difference. The characteristics of this equilibrium state can be used to estimate the production time of nuclear materials. In this study, a mathematical model and algorithm that can be applied to radio-chronometry using the radioactive equilibrium relationship were investigated, reviewed, and implemented. A Bateman equation that can analyze the decay of radioactive materials over time was used for the mathematical model. To obtain a differential-based solution of the Bateman equation, an algebraic numerical solution approach and two different matrix exponential functions (Moral and Levy) were implemented. The obtained result was compared with those of commonly used algorithms, such as the Chebyshev rational approximation method and WISE Uranium. The experimental analysis confirmed the similarity of the results. However, the Moral method led to an increasing calculation uncertainty once there was a branching decay, so this aspect must be improved. The time period corresponding to the production of nuclear materials or nuclear activity can be estimated using the proposed algorithm when uranium or its daughter nuclides are included in the target materials for nuclear forensics.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.3935-3939
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• 2023

The paper presents the results of a study of radioactive noble gases and from decay products in the atmosphere of the reactor hall of the research nuclear reactor IVV-2M. The distribution of short-lived ⁸⁸Rb and ¹³⁸Cs activity by sizes of aerosol particles was measured in the range of 0.5-1000 nm. It is shown that radioactive aerosols are characterized by three main modes with AMTD 2-3 nm, 7-15 nm and 400 nm. About 70% of aerosol activity is due to ⁸⁸Rb. The equilibrium factor between ⁸⁸Kr and ⁸⁸Rb is 0.2 ± 0.1. The total concentration of aerosols particles was measured using an aerosol diffusion spectrometer. The value of unattached fraction of radioactive aerosols in the atmosphere of reactor hall IVV2M was f = 0.15-0.25 at the average total aerosol particles concentration from 20,000 cm³ to 53,000 cm³.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2006년도 학술논문요약집
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• pp.301-301
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• 2006

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2006년도 학술논문요약집
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• pp.193-193
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• 2006

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.335-336
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• 2018

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.105-114
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• 2004

This study investigated the thermal behavior of the nuclear graphite waste generated from the decommissioning of the Korean nuclear research reactor, The first part study investigated the decomposition rate of the nuclear graphite waste up to $1000^{\circ}C$ under various oxygen partial pressures using a thermo-gravimetric analyzer (TGA). Tested graphite waste sample not easily destroyed in the oxygen-deficient condition. However, the gas-solid oxidation reaction was found to be very effective in the presence of oxygen. No significant amount of the product of incomplete combustion was formed even in the limited oxygen concentration of 4% $O_2$. The influence of temperature and oxygen partial pressure was evaluated by the theoretical model analysis of the thermo-gravimetric data. The activation energy and the reaction order of graphite oxidation were evaluated as 128 kJ/mole and 1.1, respectively. The second part of this study investigated the behavior of radioactive elements under graphite oxidation atmosphere using thermodynamic equilibrium model. $^{22}Na$, $^{134}Cs$ and $^{137}Cs$ were found be the semi-volatile elements. Since volatile uranium species can be formulated at high temperatures above $1050^{\circ}C$, the temperature of incinerator furnace should be minimized. Other corrosion/activation products, fission products and uranium were found to be the non-volatile species.

• 대한기계학회논문집B
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• 제27권10호
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• pp.1489-1497
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• 2003

Aerosol charge neutralizers with various radioactive sources have been used to apply an equilibrium charge distribution to aerosols of unknown charge distribution. However, the performance of aerosol charge neutralizers is not well known, especially for highly charged particles. Measurements of highly charged particles are needed in air cleaning devices, e.g. electrostatic precipitator, bag filter with a pre-charger, and electrical cyclone. In this study, the particle charging characteristics of two different aerosol charge neutralizers were experimentally investigated for singly charged monodisperse particles and highly charged polydisperse particles. One has radioactive source of $^{85}$ Kr (beta source, 2 mCi) and the other has $^{210}$ Po (alpha source, 0,5 mCi). The air flow rate passing through each aerosol charge neutralizer was changed from 0.2 to 2.5 L/min. The results show that the charge distribution of singly charged monodisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer is well agreed with the Boltzmann equilibrium charge distribution at an air flow rate of 0.3 L/min, However, it deviates from the equilibrium charge distribution when the air flow rates are 0.6, 1,0, and 1,5 L/min, On the other hands, the effect of air flow rate is insignificant for the $^{210}$ Po aerosol charge neutralizer. The non-equilibrium character in charge distribution of highly charged polydisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer greatly depends on the air flow rate, however it is insensitive to the air flow rate for the $^{210}$ Po aerosol charge neutralizer.

• Journal of Radiation Protection and Research
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• 제29권1호
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• pp.1-8
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• 2004

ANL에서 개발한 유 무기 복합의 신이온교환수지인 Diphosil은 silica 물질에 diphosphonic acid 그룹을 결합시킨 구조를 가지고 있다. Diphosil을 원전 운영 중 발생되는 방사성폐액 처리에 적용하기 위해 주대상 핵종인 $^{137}Cs,\;^{60}Co$을 사용하여 흡착 평형과 컬럼 실험을 수행하였다. 흡착 평형 실험을 통하여 $^{137}Cs$과 $^{60}Co$의 제거율과 그 제거율에 미치는 다양한 조건에서 비방사성 이온의 영향을 조사하였다. 대상 핵종에 대한 파과곡선은 모의 방사성 폐액을 이용한 실험실 수준의 컬럼 실험을 통해 구하였고, Diphosil의 제거능력을 현재 원전에서 쓰이고 있는 Amberlite IRN 77 수지와 비교하였다.

• 방사성폐기물학회지
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• 제8권3호
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• pp.207-213
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• 2010

국산 칼슘 벤토나이트를 대상으로 온도가 팽윤압에 미치는 영향을 관찰하였다. 벤토나이트를 건조밀도 1.6 g/$cm^3$으로 압축하고, 0.69 MPa의 일정한 수압으로 증류수를 공급하여 팽윤압을 측정하였다. 온도 영향 실험은 $25^{\circ}C$, $30^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$, $60^{\circ}C$, $70^{\circ}C$, respectively. The Ca-bentonite showed a sufficiently high swelling pressure of 5.3 MPa에서 승온조건과 감온조건으로 수행하였다. 압축 벤토나이트가 물과 접촉하여 상온에서 5.3 MPa의 충분히 높은 팽윤압이 작용하는 것을 실험적으로 확인하였다. 팽윤압은 온도가 높을수록 감소하는 것으로 나타났다. 승온조건과 감온조건에서의 온도에 따른 팽윤압 거동에 차이를 보이며, 승온조건에서 온도에 따른 변화가 심하게 나타났다. 향후 온도 조건 외에 벤토나이트의 압축밀도 변화, 지하수 조성에 따라 팽윤압 특성이 어떻게 변화하는지에 대해 평가한다면, 앞으로 국내 고준위 폐기물 처분장의 개념 설계에 유용하게 활용될 수 있을 것으로 본다.