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Fixation of $\gamma$-Radionuclides by the PVA-PMAA System
Won, Hui-Jun,Ahn, Byung-Gil,Jung, Chong-Hun,Kim, Gye-Nam,Oh, Won-Zin Korean Nuclear Society 2000 Nuclear Engineering and Technology Vol.32 No.3
A series of laboratory experiments was conducted to investigate the fixation characteristics of poly(vinylalcohol)-poly(methacrylic acid)(PVA-PMAA) mixed solution on the soluble ${\gamma}$- radionuclides. Using the potentiometric titration technique, it was found out that the PVA and PMAA in a solution form intermacromolecular complex. The mobilized portion of each radionuclide by water from sand surface treated with a fixative was measured by ${\gamma}$-ray spectroscopy. The mobilized portion of minor radionuclides such as 241Am, 154Eu, 155Eu and 144Ce were higher than those of 134Cs and 137Cs. The capability of PVA-PMAA system was better among the candidate solutions for the fixation of total ${\gamma}$-radioactivity. 134,137Cs which is composed of more than 85 % of total ${\gamma}$-radioactivity could be fixed effectively by the PVA-PMAA solution.
Studies on Electrokinetic Remediation of Radioactively Contaminated Soil By Using Sulfuric Acid
Won-Zin Oh,Gye-Nam Kim 한국방사성폐기물학회 2004 방사성폐기물학회지 Vol.2 No.2
10년 이상 된 방사능오염 토양에서 동전기적 방법에 의한 Cs과 Co의 제염효율을 높이기 위해 HSO과 시트르산을 첨가제로 사용했다. 동전기 토양복원 컬럼의 방출수 평균속도는 2.0 cm/min이고, 10일 동안 방출된 토양폐액의 부피는 컬럼의 3.6 공극부피다. 10일간 Cs 의 제거효율이 54%에 불과한 반면에, Co는 97%나 제거되었다. 이것은 Cs의 흡착평형계수가 Co 보다 크기 때문이라고 생각된다. 본 연구에서 제시한 수학적 모델에 의한 컬럼 잔류 오염도는 실험 오차 범위에서 실험결과와 잘 일치하였다. H2SO4 and citric acid were used as additives for the electrokinetic remediation experiment to increase removal efficiency of Cs and Co from the radioactive soil waste stored for more than 10 years. The average effluent velocity discharged from the elctrokinectic remediation experimental column was 2.010 cm/min and the discharged soil wastewater volume for 10 days is 3.6 pore volume of the column. 97% of Co in the column was decontaminated for 10 days of operation, while only 54% of Cs was decontaminated. These results are considered that the absorption equilibrium coefficient of Cs is higher than that of Co. The predicted values of the residual concentration by the proposed mathematical model were well coincided with the experimental results within the experimental error range
Hui-Jun Won,Min-Gil Kim,Gye-Nam Kim,Chung-Hun Jung,Jin-Ho Park,Won-Zin Oh 한국방사성폐기물학회 2005 방사성폐기물학회지 Vol.3 No.1
Cs 이온에 대해 선택성을 갖는 ferrocyanide-음이온 교환수지를 제조하여 모의 제 염폐액 내에 존재하는 Cs 이온에 대한 흡착실험을 수행하였다. 제조된 이온교환 수지가 citric acid를 주제염제로 하는 제염폐액 내에 존재하는 Cs+ 이온에 대한 흡착능력은 상용 양이온교환수지에 비해 4배 이상 효과적인 것으로 나타났다. 모의 제염폐액과 선택성 이온교환수지를 접촉시킨 후 360분이 경과하면 금속이온에 대한 흡착반웅이 평형에 도달하였다. 본 연구범위에서 Co 이온농도가 필요이상 증가하게 되면 Cs 이온의 흡착율은 감소하였다. 과산화수소와 히드라진을 사용한 선택성 폐 이온교환수지의 재생실험 결과 전기중성화조건을 만족시키기 위해 Cs 이온이 수지로부터 용출됨을 확인하였고 열화없이 재 사용가능성을 확인하였다. Preparation of ferrocyanide-anion exchange resin and adsorption test of the prepared resin on the Cs$ion were performed. Adsorption capability of the prepared resin on the Csion in the simulated citric acid based soil decontamination waste solution was 4 times greater than that of the commercial cation exchange resin. Adsorption equilibrium of the prepared resin on the Csion reached within 360 minutes. Adsorption capability on the Csion became to decrease above the necessary Coion concentration in the experimental range. Recycling test of the spent ion exchange resin by the successive application of hydrogen peroxide and hydrazine was also performed. It was found that desorption of Csion from the resin occurred to satisfy the electroneutrality condition without any degradation of the resin.
PFC Ultrasonic Decontamination Efficiency on the Various Types of Metal Specimens
Hui-Jun Won,Gye-Nam Kim,Chung-Hun Jung,Jin Ho Park,Won Zin Oh 한국방사성폐기물학회 2005 방사성폐기물학회지 Vol.3 No.4
Type 304 stainless steel 시편에 느슨하게 붙어있는 분말에 대한 초음파 제염 거동을 조사하였다. 매질을 물, PFC 및 의 음이온 계면활성제를 함유한 PFC 용액으로 변화시킴에 따라 제염계수는 20, 50 및 200으로 증가하였다. 제염계수에 차이가 생기는 이유를 초음파 매질의 표면장력 및 양으로 하전된 산화물 표면과 음이온 계면활성제 사이의 상호작용에 기인한 것으로 설명할 수 있었다. 음이온 계면활성제를 함유한 PFC 용액 내에서 분말로 오염된 평면 시편, 파이프 시편, 틈새 시편 및 용접 시편에 대한 초음파 제염 효과를 관찰하였다. 연구된 모든 시편에 대해, 대부분의 오염물이 완벽하게 제거되는 것으로 나타났다. 길이가 6cm인 파이프 시편에 대해서는 오염물의 가 제거되었다. Ultrasonic decontamination of the type 304 stainless steel specimen loosely contaminated with powders was investigated. Decontamination factors (DFs) by the three kinds of ultrasonic media such as water, pure PFC (Pefluorocarbon, ) and a mixed solution of anionic surfactant were determined. The determined DF values were 20, 50 and 200, respectively. This significant difference in the decontamination factors for the different decontamination solution was well explained by the surface tension of the media as well as the interaction between the positively charged surface of powders and the anionic surfactant. Ultrasonic decontamination behavior of the loosely contaminated metal specimens such as plate, pipe, welding specimen and crevice specimen in the mixed solution of PFC and anionic surfactant was also investigated. The contaminants were completely removed for the tested specimens except for the longest specimen. For 6-cm long pipe specimen, however, of the contaminants were removed.
PARTITIONING RATIO OF DEPLETED URANIUM DURING A MELT DECONTAMINATION BY ARC MELTING
민병연,최왕규,WON-ZIN OH,정종헌 한국원자력학회 2008 Nuclear Engineering and Technology Vol.40 No.6
In a study of the optimum operational condition for a melting decontamination, the effects of the basicity, slag type and slag composition on the distribution of depleted uranium were investigated for radioactively contaminated metallic wastes of iron-based metals such as stainless steel (SUS 304L) in a direct current graphite arc furnace. Most of the depleted uranium was easily moved into the slag from the radioactive metal waste. The partitioning ratio of the depleted uranium was influenced by the amount of added slag former and the slag basicity. The composition of the slag former used to capture contaminants such as depleted uranium during the melt decontamination process generally consists of silica (SiO₂), calcium oxide (CaO) and aluminum oxide (Al₂O₃). Furthermore, calcium fluoride (CaF₂), magnesium oxide (MgO), and ferric oxide (Fe₂O₃) were added to increase the slag fluidity and oxidative potential. The partitioning ratio of the depleted uranium was increased as the amount of slag former was increased. Up to 97% of the depleted uranium was captured between the ingot phase and the slag phase. The partitioning ratio of the uranium was considerably dependent on the basicity and composition of the slag. The optimum condition for the removal of the depleted uranium was a basicity level of about 1.5. The partitioning ratio of uranium was high, exceeding 5.5 103. The slag formers containing calcium fluoride (CaF₂) and a high amount of silica proved to be more effective for a melt decontamination of stainless steel wastes contaminated with depleted uranium.
Electrosorption of U(IV) by Electochemically Modified Activated Carbon Fibers
Chong-Hun Jung,Won-Zin Oh,Yu-Ri Lee,Soo-Jin Park 한국탄소학회 2005 Carbon Letters Vol.6 No.1
The electrosorption of U(VI) from waste water was carried out by using an activated carbon fiber (ACF) felt electrode in a continuous electrosorption cell. In order to enhance the electrosorption capacity at a lower potential, the ACF was electrochemically modified in an acidic and a basic solution. Pore structure and functional groups of the electrochemically modified ACF were examined, and the effects of the modification conditions were studied for the adsorption of U(VI). Specific surface area of all the ACFs was decreased by this modification. The amount of the acidic functional groups decreased with a basic modification, while the amount increased a lot with an acidic modification. The electrosorption capacity of U(VI) decreased on the acid modified electrode due to the shielding effect of the acidic functional groups. The base modified electrode enhanced the capacity due to a reduction of the acidic functional groups. The electrosorption amount of U(VI) on the base modified electrode at .0.3 V corresponds to that of the as-received ACF electrode at .0.9 V. Such a good adsorption capacity was due to a reduction of the shielding effect and an increase of the hydroxyl ions in the electric double layer on the ACF surface by the application of negative potential.