LILW disposal repository in Gyeongju, South Korea is considered with a concrete mixture that uses Ordinary Portland Cement (OPC) partially substituted with supplementary cementitious materials (SCMs). The degradation of cementitious materials that result from chemical and physical attacks is a major concern in the safety of radioactive waste disposal. We present a reactive transport model utilized as one of the geochemical simulation approaches for the timescales of concern that range from hundreds to thousands of years. The purpose of this study is to investigate the sensitivity of parameters in concrete disposal systems and to evaluate the influence of various assumptions on the chemical degradation of the systems using a reactive transport model. A reactive transport model in the concrete disposal vault was developed to evaluate the behavior of engineered barriers composed of cementitious materials. The sensitivity analysis was performed using reactive transport models through the coupling between COMSOL and PHREEQC. The databases selected for the analysis are the Thermochimie database presented by ANDRA. Among many variables considered, two variables that can highly affect chemical degradation were selected for detailed sensitivity analysis for dealing with uncertainties. This is important because the chemical degradation mechanism is generally sensitive to precipitation and diffusion coefficient. The first factor is precipitation, which might be the most important factor in chemical degradation because it acts as a calcium leaching of cementitious materials in a disposal system in a highly alkaline environment, increasing the porosity of the system. To predict the change in annual precipitation, the measurement of the precipitation observatory station in the nearest area of Gyeongju for the past 80 years was collected. The second factor is the diffusion coefficient, which plays an essential role in the durability of the concrete disposal system, promoting the decalcification of cementitious minerals, accelerating system degradation, and increasing the porosity of its system, thereby facilitating the migration of radionuclides. The diffusion coefficient values used in studies similar to this work were calculated and evaluated using the box-and-whisker method. The results of the sensitivity analyses for the reactive transport model in the concrete disposal system will be presented. The sensitivity cases show that the results obtained are much more sensitive to changes in transport parameters.

The bacterial soft-rot disease is one of the most critical diseases in vegetables such as Chinese cabbage. The researchers isolated two bacteria (Pseudomonas kribbensis and Pantoea vagans) from diseased tissue samples of Chinese cabbages and confirmed them as being the strains that cause soft-rot disease. Lactic-acid bacteria (LAB), were screened and used to control soft-rot disease bacteria. The researchers tested the treatments with hypochlorous acid water (HAW) and LAB supernatant to control soft-rot disease bacteria. The tests confirmed that treatments with the HAW (over 120 ppm) or LAB (Lactobacillus plantarum PL203) culture supernatants (0.5 mL) completely controlled both P. kribbensis and P. vagans.

본 연구는 백미 등 9품목에서 트리코테센류 A형 곰팡이 독소인 T-2와 HT-2 독소의 함량을 구하고 전체인구집단의 곡류 섭취로 인한 트리코테센류 A형 곰팡이독소인 T-2와 HT-2 독소의 노출 수준에 따른 위해성을 평가하고자 하였 다. 우리나라 전체 인구집단의 트리코테센류 A형 T-2와 HT-2 독소의 노출수준을 산출하기 위해 결정론적 위해평가 를 수행하였다. 산출된 노출량은 JECFA에서 제시한 TDI (100 ng/kg b.w./day) 대비 위해도(%)를 구하여 노출수준에 대한 위해정도를 파악하였다. 9품목 곡류 115건에 대한 트 리코테센류 A형 곰팡이독소인 T-2와 HT-2 독소의 함량은 LC-MS/MS를 이용하여 구한 결과 트리코테센류 A형 곰팡 이독소인 T-2와 HT-2 독소의 합으로 평균 7.80 μg/kg (0.00-7.80) 수준으로 검출되었다. 곡류섭취로 인한 전연령 의 평균섭취량을 고려하였을 때 트리코테센류 A형 곰팡이 독소인 T-2와 HT-2 독소 섭취량은 0.57 ng/kg b.w./day (LB), 1.39 ng/kg b.w./day (MB), 2.2 ng/kg b.w./day (UB)으로 TDI 대비 0.57% (LB), 1.39% (MB), 2.2% (UB) 수준 이 었다. 극단(P95) 섭취량을 고려하였을 때 트리코테센류 A 형 곰팡이독소인 T-2와 HT-2 독소 섭취량은 11.06 ng/kg b.w./day (LB), 13.95 ng/kg b.w./day (MB), 16.87 ng/kg b.w./ day (UB)으로 TDI 대비 11.06% (LB), 13.95% (MB), 16.87% (UB) 수준이었다. 따라서, 우리나라 국민들의 곡류 섭취로 인한 트리코테센류 A형 곰팡이독소인 T-2와 HT-2 독소 노출수준은 위해 우려가 낮은 수준으로 평가되었다.

PTMSP에 0∼50 wt% NaA Zeolite를 첨가하여 PTMSP-NaA Zeolite 복합막을 제조하고, PTMSP-NaA Zeolite 복합막의 특성을 FT-IR, 1H-NMR, GPC, DSC, TGA, SEM에 의해서 조사하였다. PTMSP-NaA Zeolite 복합막의 수소와 질소에 대한 투과도와 선택성을 NaA Zeolite 함량에 따라 조사하였다. TGA측정에 의하면 PTMSP에 NaA Zeolite가 첨가되었을 때 복합막의 감량이 완결되는 온도는 낮아졌고, 감량(wt%)도 작아졌다. SEM관찰에 의하면 NaA Zeolite는 PTMSP-NaA Zeolite 복합막 내에 2∼5 μm 크기로 분산되어 있었다. PTMSP-NaA Zeolite 복합막에 대한 N2와 H2의 투과도는 NaA Zeolite 함량이 증가하면 증가하였다. 그리고 PTMSP-NaA Zeolite 복합막의 N2에 대한 H2의 선택성은 NaA Zeolite함량이 증가하면 감소하였다.