• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1206-1212
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• 2022

Cold-crucible induction melting (CCIM) technology has been intensively studied as an advanced vitrification process for the immobilization of highly radioactive waste. This technology uses high-frequency induction to melt a glass matrix and waste, while the outer surface of the crucible is water-cooled, resulting in the formation of a frozen glass layer (skull). In this study, for the fabrication of borosilicate glass waste form, CCIM operation test with 60 kg of glass per batch was conducted using surrogate wastes composed of Cs, Sr, and Nd as a representative of highly radioactive nuclides generated during spent nuclear fuel management. A 60 kg-scale glass waste form was successfully fabricated through melting and draining processes using a CCIM system, and its physicochemical properties were analyzed. In particular, to enhance the controllability and reliability of the draining process, an air-cooling drain control method that can control draining through air-cooling near drain holes was developed, and its validity for draining control was verified. The method can offer controllability on various draining processes, such as molten salt or molten metal draining processes, and can be applied to a process requiring high throughput draining.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.650-654
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• 2003

원자력분야에서 방사성폐기물 처리 및 처분은 해결해야 할 중요한 문제가 된다. 보다 청정한 방법을 사용한 제염법이 요구되고 있다. 이산화탄소를 이용한 제염법은 두가지로 나눠지는데-킬레이트제를 이용한 방법과 에멀젼을 이용한 방법이다. 킬레이트제 방법은 시너지효과를 낼 수 있는 방안이 중요하다. 마이크로 에멀젼을 사용한 방법은 에멀젼 코어속에 산을 넣어 금속표면이나 토양에서 오염물질을 직접 꺼내는 방법이다. 표면제거율을 QCM을 사용하여 측정하였다. 에멀젼을 만드는데 사용된 계면활성제의 회수 방법에 대하여 아울러 논의하였다.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1830-1837
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• 2023

The thermal cutting of contaminated or activated metals during decommissioning nuclear power plants inevitably results in the release of radioactive aerosol. Since radioactive aerosols are pernicious particles that contribute to the internal dose of workers, air conditioning units with a HEPA filter are used to remove radioactive aerosols. However, a HEPA filter cannot be used permanently. This study evaluates the efficiency and lifetime of filters in actual metal cutting condition using a plasma arc cutter and a high-resolution aerosol detector. The number concentration and size distribution of aerosols from 6 nm to 10 ㎛ were measured on both the upstream and downstream sides of the filter. The total aerosol removal efficiency of HEPA filter satisfies the standard of removing at least 99.97% of 0.3 ㎛ airborne particles, even if the pressure drop increases due to dust feeding load. The pressure drop and particle size removal efficiency at 0.3 ㎛ of the HEPA filter were found to increase with repeated cutting experiments. By contrast, the efficiency of used HEPA filter reduced in removing nano-sized aerosols by up to 79.26%. Altogether, these results can be used to determine the performance guidance and replacement frequency of HEPA filters used in nuclear power plants.

• 방사성폐기물학회지
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• 제19권2호
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• pp.233-241
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• 2021

A series of three bench-scale experiments was performed to investigate the conversion of sodium metal to sodium chloride via reactions with non-metal and metal chlorides. Specifically, batches of molten sodium metal were separately contacted with ammonium chloride and ferrous chloride to form sodium chloride in both cases along with iron in the latter case. Additional ferrous chloride was added to two of the three batches to form low melting point consolidated mixtures of sodium chloride and ferrous chloride, whereas consolidation of a sodium-chloride product was performed in a separate batch. Samples of the products were characterized via X-ray diffraction to identify attendant compounds. The reaction of sodium metal with metered ammonium chloride particulate feeds proceeded without reaction excursions and produced pure colorless sodium chloride. The reaction of sodium metal with ferrous chloride yielded occasional reaction excursions as evidenced by temperature spikes and fuming ferrous chloride, producing a dark salt-metal mixture. This investigation into a method for controlled conversion of sodium metal to sodium chloride is particularly applicable to sodium containing elevated levels of radioactivity-including bond sodium from nuclear fuels-in remote-handled inert-atmosphere environments.

• 대한화학회지
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• 제15권4호
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• pp.199-203
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• 1971

The adsorption method for the determination of the formation constants of the metal complexes with organic acids was developed by using membrane filters. The adsorption method involved the measurements of radioactivities of the adsorbed metal on membrane filters and the filtrate solution after the radioactive metal ion were filtered through membrane filters in the presence of organic ions of varying concentration. Comparing the adsorption method with the ion exchange method, it was seen that the adsorption method was simpler and faster than the ion exchange method. As an example of the metal complex with organic acid yttrium citrate complex was chosen, and the formation constant of the complex obtained by the adsorption method showed $K_f=2.0{\times}10^{-4}(l. mole^{-1})$ at a pH of 7. Also the present study revealed that the carrierfree state of yttrium in aqueous solution was present in the completely ionized state.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.183-183
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• 2018

In this study, 5-bromo-2,9-bis(5,6-diphenyl-1,2,4-triazin-3-yl)-1,10-phenanthroline (5-bromo-Ph4-BTPhen) was synthesized and evaluated for its ability to remove major radionuclides ($Cs^+$, $Sr^{2+}$, and $Co^{2+}$). The synthesized ligand removed both $Sr^{2+}$ and $Co^{2+}$ from $1mg\;L^{-1}$ aqueous solutions with extraction efficiencies of up to 99% at neutral and alkaline pH. The $Sr^{2+}$ and $Co^{2+}$ removal efficiencies decreased as a consequence of the higher bonding strengths of competing metal ions to the N-donor atoms in the cavity of the ligand; competing divalent ions affected the $Sr^{2+}$ and $Co^{2+}$ removal efficiencies more than monovalent ions.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1878-1886
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• 2021

For industrial package (IP)-type transport containers for radioactive materials, a free drop test should be conducted under regulatory conditions. Owing to various uncertainties observed during the drop test, errors in drop angles inevitably occur. In IP-type metal transport containers in which the container directly impacts onto a rigid target without any shock absorbing materials, the error in the drop angle due to a slight misalignment makes a significant difference from the ideal drop. In particular, in a vertical drop, the error in the drop angle causes a strong secondary impact. In this paper, a numerical method is proposed to estimate the error in the drop angle occurring during the test. To determine this error, an optimization method accompanying a computational drop analysis is proposed, and a surrogate model is introduced to ensure calculation efficiency. Effectiveness of the proposed method is validated by performing the verification and comparison between the test and the analysis applied with the drop angle error.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.109-116
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• 2003

국내 원자력 산업의 급속한 성장과 더불어 하나로 시설의 본격적인 가동 및 핵연료주기시험과 관련한 연구의 증가로 인하여 방사성폐기물의 발생량 및 누적량이 지속적으로 증가될 전망이며, 이에 따라 방사성폐기물의 안전성 확보 및 감용 처리를 위한 노력이 더욱 강조되고 있다. 조사후시험시설에서는 원자력발전소에서 발생하는 사용후핵연료봉의 결함원인 규명과 건전성 평가를 위한 조사후시험을 수행하고 있으며, 본 연구에서는 조사후시험시설에 설치되어 있는 방사성고체폐기물 처리설비를 활용하여 조사후시험에서 발생하는 폐기물의 압축, 파쇄, 절단기술 및 경험사례에 대하여 기술하였다. 고준위 방사성고체폐기물 처리는 특수 제작하여 핫셀에 설치되어 있는 100톤 압축기로 방사성고체폐기물을 압축하여 폐기물의 양을 1/12정도로 감용 처리하였으며, 중ㆍ저 위 방사성고체폐기물은 인터벤션에 설치된 60톤 압축기를 사용하여 가연성폐기물을 1/8정도로 압축 감용 처리하였다. 폐플라스틱 통은 파쇄기를 사용하여 절단처리 함으로써 1/5, 폐 필터는 1/6의 감용 비를 얻었으며, 비 가연성물질인 금속류 물질 또한 절단 처리하여 드럼의 양을 줄일 수 있었다.

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2002년도 International Symposium on Magnetic Resonance
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• pp.72-72
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• 2002

In most traditional sorption study in environmental conditions, experimental sorption data have been measured and interpreted by empirical ways such as partition coefficient and sorption isotherms. A mechanistic understanding of heavy metal interactions with various minerals (metal oxides, clay minerals) in aqueous medium is required to describe the behavior of radioactive metal ions in the environment. Various spectroscopic methods provide direct or indirect information on sorption mechanisms involved. We applied EPR (Electron Paramagnetic Resonance) spectroscopy to investigate the nature of metal ion sorption at water/mineral interfaces using Cu(II) as a spin probe. The major sorbed species and their motional state was identified by their EPR spectra. They showed distinct signals due to their strength of binding, local structure and motional state. The EPR results together with macroscopic sorption data show that sorption involved at least three different mechanisms depending on chemical environments (1).

• Journal of Radiation Protection and Research
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• 제25권2호
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• pp.99-107
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• 2000

플라즈마 아크 용융방식 유리화 시험설비의 계통내 기체 및 최종배출구 전단의 배기체를 분석함으로써 배기체중에 포함된 분석용 첨가물의 거동 및 배기가스 처리장치의 제염성능을 평가하였다. 중금속 물질(Pb, Cd, Hg), 방사성 모의물질(Co, Cs) 그리고 방사성핵종($^{60}Co,\;^{137}Cs$)을 분석용 첨가물로 사용한 실험결과로부터 첨가물질의 거동에 따른 유리화 설비 배기체처리시스템의 제염특성 및 제염제수를 구하였다.