Mobility of radionuclides (RNs) in natural water systems can be increased by complex formation with organic materials. In alkaline cement pore-water conditions, cellulose materials in radwastes such as woods and papers are degraded fast to small organic materials. As a major cellulose degradation product, isosaccharinate (ISA) has been paid attention recently due to its effect on facilitating RNs migration. ISA contains a carboxyl and four hydroxyl functional groups, which cooperatively interact to form chelating bonds with positively charged radionuclides. In our previous study, we determined thermodynamic formation constants, reaction enthalpy and entropy of trivalent americium complexes with ISA, Am(ISA)n (3-n)+ (n=1, 2), in weak acidic condition by conducting temperature-dependent UVVis absorption spectroscopy. Based on those thermodynamic constants along with the experimental results from time-resolved laser induced fluorescence spectroscopy and DFT calculations, we suggested two different chelating-modes of ISA on Am(III). It is more relevant to study Am(III)-ISA complexation under alkaline conditions around pH 12.5, which correspond to the pore-water condition of calciumsilicate- hydrate. Under the alkaline conditions, deprotonated hydroxyl groups of ISA can form more strong interactions with Am. Aquatic hydroxide group can also act as a ligand to form ternary Am(III) -ISA-OH complexes. In this study, absorption spectra of Am-ISA systems were monitored with two variations: first, pH variation (5.5–13) in the presence of constant 30 mM ISA, and second, ISA concentration variation (20 μM – 30 mM) at constant pH of 12.5. As increasing the pH at constant 30 mM ISA, absorption spectra of Am(ISA)2 + were red-shifted from 506.3 to 509.5 nm. The samples showed stable absorption spectra over 30 days. On the other hand, samples with lower ISA concentrations below 10 mM at pH 12.5, showed gradual decrease in the absorbance as sample aging time. By examining filtrates after ultrafiltration (1 kDa), we confirmed that aqueous Am(III)-ISA complexes were formed in the presence of 30 mM ISA at pH 12.5, while colloidal particles and precipitations were formed in the conditions of ISA concentrations lower than 10 mM. In this presentation, we will discuss about probable ternary complex forms of Am(III)-ISA-OH, colloidal forms, and solubility of Am(III) as a function of ISA concentration under alkaline conditions. Absorption and luminescence spectroscopic properties of the Am(III)-ISA-OH ternary system will also be presented.

Radioactive nickel (Ni59 and Ni63) is a major radionuclide that needs to be determined for quantifying the total radioactivity in radioactive waste disposal repository. Also, radioactive waste containing organic wastes, such as cotton and tissue can be decomposed to produce the Isosaccharinic acid (ISA) in a disposal facility. The presence of ISA in the disposal facility could increase the mobility of radionuclides. Therefore, it is necessary to confirm the mobility of Ni with the presence of ISA in the repository. This study investigated the effect of ISA on the sorption and the solubility of Ni in synthesized groundwater. The sorption test was conducted in different time intervals with Ni and ISA. Nickel nitrate hexahydrate and Ca(ISA)2 were used after purchase. Granite was used as the solid medium to simulate the major rock type of the repository. Ni and ISA solution with the medium were mixed using a platform shaker for 6 days. After 6 days, the solid parts were separated by centrifugation and additional syringe filters, and the supernatant was analyzed for Ni and ISA concentration using ICP-MS and IC, respectively. The solubility experiments were conducted at different temperatures (20, 40, and 80°C). Nickel hydroxide was used as the solubility limiting solid phase. To balance the ionic strength and confirm the effect of ISA on Ni solubility, 0.01 M of CaCl2 solution was prepared in a sample without ISA, and 0.01 M of Ca(ISA)2 solution was prepared in a sample with ISA. In solubility tests, the solution was also analyzed by ICP-MS and IC for Ni and ISA, respectively. The concentration of Ni was found to increase with ISA compared to Ni concentration without ISA. The concentration of ISA was not changed during the solubility test periods. For solubility tests, the concentration of Ni also increased according to the increase in temperature. The solid phase was characterized by XRD, FT-IR, and SEM-EDS. Based on the results of this study, the presence and effect of ISA on radioactive Ni mobility should be carefully investigated to secure the long-term safety assessment for the low and intermediate-level waste repository.

Radionuclides stored in a radioactive waste repository over a long period of time might be leached through the barriers such as engineered rock (cement) and natural rock (granite). Organic complexing agents such as ethylenediaminetetraacetic acid (EDTA) and isosaccharinic acid (ISA) may also influence the mobility of radionuclides. In this study, a continuous fixed-column reactor packed with engineered and natural rocks was designed to investigate the effect of organic complexing agents on cesium mobility through cement and granite under anaerobic conditions. The influent flow rate of the mixed solution (organic complexing agent and cesium) at the column bottom was 0.1 mL/min, while that of groundwater was 0.2 mL/min, which was introduced between cement and granite layers in the middle of the column. The hydraulic properties such as diffusion coefficient and retardation factor were derived by a bromide tracer test. The effects of different operating parameters, such as initial cesium concentrations, initial EDTA or ISA concentrations, and bed size, on the cesium adsorption were investigated. The Thomas, Adams-Bohart, and Yoon-Nelson models were applied to the experimental data to predict the breakthrough curves using non-linear regression. These results suggest that organic complexing agents such as EDTA and ISA significantly influence the mobility of cesium in the barriers, indicating that the presence of complexing agents enhances the migration of cesium to the geosphere.

Radionuclides can be leached into groundwater or soil over a long period of time due to unexpected situations even after being permanently disposed of in a repository. Therefore, it is necessary to investigate the mobility of radionuclides for the safety assessment of radioactive waste disposal. In this study, the effects of organic complexing agents such as ethylenediaminetetraacetic acid (EDTA) and isosaccharinic acid (ISA) on the sorption behavior of 239Pu and 99Tc over cementitious (concrete and grout) and natural rock samples (granite and sedimentary rock) were investigated in batch sorption experiments. For characterization of rock samples, XRD, XRF, FT-IR, FE-SEM, BET, and Zeta-potential analyses were performed. For the evaluation of mobility, the distribution coefficient (Kd) was selected and compared. The adsorption experiment was carried out at two pHs (7 and 13), a temperature of 20°C, and a range of organic complexing agents concentrations (10-7~10-2 M and 10- 5~10-2 M for 239Pu and 99Tc, respectively). The radionuclides concentrations in adsorption samples were analyzed using ICP-MS. The Kd values for 239Pu in all rock samples reduced significantly due to the presence of EDTA, even at low concentrations such as 10-5 M. In the case of ISA, the limiting noeffect concentration was much higher than that of EDTA. On the other hand, 99Tc showed relatively lower Kd values than 239Pu, and the sorption behavior of 99Tc was almost unaffected by the organic complexing agents for all rock samples. Therefore, it is possible to assume that the increased mobility of radionuclides, especially, 239Pu, in groundwater caused by the lowering of sorption at even low concentrations of organic complexing agents may result in the transport of radionuclides to the nearand far-field location of the repository.

Technetium (Tc) is a long-lived radioactive isotope, which exists as TcO4 - with high solubility under oxidative condition. The solubility of Tc is fundamental to assess the safety of radioactive waste repository in the case of a leakage of radioactive wastes. Cellulosic materials (paper, wood, cotton, etc.) contaminated by radionuclides are disposed of in low-level and intermediate-level radioactive waste repositories. Cellulose can be decomposed under anaerobic and alkaline conditions when cement pore water is saturated, and then isosaccharinic acid (ISA) is generated as a degradation product of cellulose. ISA forms complexations with radionuclides in solution and affects the solubilities of radionuclides. Therefore, the effect of ISA should be accurately evaluated to predict and assess the mobility of radionuclides in repository environments. In this study, batch tests were conducted to confirm the effect of ISA on the solubility of Rhenium(IV) Oxide. Herein, rhenium was used as a non-radioactive analog of Tc due to their similar chemical properties. Deionized water (DIW) and 0.1 M NaOH solution in pH 12.5 were used as background solutions, and ISA concentration was varied to 1~20 mM using Ca(ISA)2 and NaISA, respectively. The batch tests were conducted under both aerobic and anaerobic conditions. The whole batch tests under anaerobic conditions were performed in the glove box using oxygen purged DIW with a high purity nitrogen gas (99.9%) and low oxygen concentration (< 0.5 ppm). As a result, the rhenium concentration decreases as more ISA is dissolved in the solution, which shows the contrary effect of ISA on the solubility of other metals and radionuclides (e.g., Co, Th, Fe, Ni, etc.). It is assumed that the reducing capacity of ISA decreases the rhenium dissolution in the solution. Additional characterization of the oxidation state of rhenium oxide and the mechanism will be tested and presented.

Safety for the radioactive waste disposed of in the disposal facility should be secured through safety assessment in consideration of the various situations. In this study, the influence and correlation of EDTA and ISA, which are the factors that can impede the safety of the disposal facility, were analyzed using the PHREEQC computational code. Thermodynamic database (TDB) of Andra, specific ion interaction theory (SIT) model as ionic strength correction model, radionuclides (Ni, Am, Pu) were adopted to perform the calculation on the distribution of chemical species by pH. According to the results, EDTA dominated the system and the effect of ISA is relatively small for the distribution of the chemical species of divalent and trivalent cations in neutral and weak base conditions. In the case of the tetravalent cations, the effect of ISA increased compared to the previous case especially in the strong base conditions. In conclusion, EDTA has a more significant effect on the system than ISA under the environment of the domestic disposal facility. Furthermore, when EDTA and ISA are present simultaneously in the system, the effects of two materials are inversely proportional and this characteristic should be considered during the safety assessment.

이 글은 오영수의 ｢이사｣ 발표 지면을 확인하기 위한 것이다. ｢이사｣는 1951년 발표로 알려져 있다. 그런데 1951년 ｢이사｣를 발표했다는 잡지 󰡔문예󰡕는 1951년에 발간되지 않은 것으로 확인된다. 따라서 이 글은 ｢이사｣가 들어있는 1953년 부산지역 잡지를 발굴하여 오영수 작품 연대를 보완하고자 한다. ｢이사｣가 발표된 지역 잡지는 남선전기주식회사에서 발행한 󰡔전우󰡕이다. 1953년 창간된 󰡔전우󰡕는 부산에서 나온 사외보로써 전기 문명에 대한 홍보와 더불어 구성원들의 소통과 교양을 위하여 창간되었다. 거의 절반 분량의 문예란을 두고 있는 것이 특징이다. ｢이사｣는 창간호 문예란에서 발견되었다. 이 글은 단편소설의 대가로 알려진 오영수의 ｢이사｣에 대한 서지학적 연구로써 지금까지 알려지지 않은 발표 지면을 발굴하였 다. 이를 통하여 지역 문학 연구를 위한 지역 잡지 발굴의 중요성을 확인하였다

상사호에서 순천만까지 짧은 수역 특성을 나타내는 이 사천 수계 (Isa Stream systems)의 수질 환경 및 식물플랑크 톤 군집의 시ㆍ공간 분포 특성을 분석하였다. 결과, 상사호는 상대적으로 빈영양 및 중영양 조건을 나타내지만, 순천만에 이루는 담수역과 기수역은 축산폐수 등 산업폐수의 영향으로 상사호 및 해수역보다 극심한 부영양상태를 나 타내었다. 식물플랑크톤 군집은 상사호와 순천만보다 담수역 및 기수역에서 출현 종수가 높았지만, 현존량 및 엽록소 a 농도는 상사호와 해수역에서 상대적으로 높게 나타났다. 특히 봄과 여름 상사호는 중영양종인 Fragilaria crotonensis와 Asterionella formosa가 표층과 저층에서 서로 다른 우점 현상을 보이는 것으로 댐 하류의 담수역과 기수 역에서는 A. formosa에 의한 영향이 크게 나타났다. 그러나 가을과 겨울은 기수역에서 해수역까지 부영양화 지표종인 Skeletonema costatum-ls가 극우점하였다. 즉 이사천 수계의 급격한 환경변화는 순천만 연안생태계 구조를 심각하게 훼손시킬 수 있을 것으로 판단되었다. 급격한 연안생태계 변화는 한국 제1호 람사르습지인 순천만 및 순천 생물권보 전지역 및 최대 꼬막 산지인 여자만의 효율적 이용과 관리, 그리고 보전이라는 측면에서 매우 위협적인 내용이기에, 더욱 심층적인 관리방안 도출이 요구된다고 할 수 있다.

본 연구는 도시재생 선도지역으로 지정된 곳이자 순천부읍성의 중심지역으로 700년의 역사성과 장소성을 지닌 순천 시 문화의 거리를 대상지로 중요도-만족도 매력속성을 분석하여 다음과 같은 결론을 도출하였다. 문화의 거리 중요도와 만족도간의 차이분석에서는 19개 모든 항목에서 기대속성인 중요도와 성취속성인 만족도간의 항목들이 서로 일치하고 있었으며, 중요도에 비해 만족도가 낮게 나타나 방문객의 높은 요구에 대응하기 위해서는 지속적인 개선방안이 요구되 었다. 전체 중요도는 3.65, 전체만족도는 3.17로 평균이상으로 평가되었다. ISA 결과, 중요도와 만족도가 모두 높은 매력속성으로는 접근성, 서비스, 대표성 등으로 나타나 이는 순천시 문화의 거리의 경쟁우위에 있는 강점들로 분석되었고, 전통성, 편의성, 야간이용시 안전성 등은 중요도에 비해서 만족도가 낮은 항목들로 분석되어 도시재생 및 문화의 거리의 활성화를 위해서는 다양한 정책의 변화와 체계적인 관리방안이 필요한 것으로 평가되었다.