Molten Salt Reactor, which employs molten salt mixture as fuel, has many advantages in reactor size and operation compared to conventional nuclear reactor. In developing Molten Salt Reactor, the behavior of fission product in operation should be preliminary evaluated for the correct design of reactor and its associated system including off-gas treatment. In this study, for 100 Mw 46 KCl- 54 UCl3 based Molten Salt Reactor with operating life time of 20 year, the fission product behavior was estimated by thermodynamic modeling employing FactSage 8.2. Total inventory of all fission product were firstly calculated using OpenMC code allowing depletion during neutronic calculation. Then, among all inventory, 46 element species from Uranium to Holmium were chosen and given to the input for equilibrium module of Factsage with its mass. In phase equilibrium calculation, for the correct description of solution phase, KCl-UCl3 solution database based on modified quasichemical model in the quadruplet approximation (ANL/CFCT-21/04) was employed and the coexisting solid phase was assumed to pure state. With the assumption of no oxygen and moisture ingress into reactor system, equilibrium calculation showed that 1% of solid phase and of gas phase were newly formed and, in gas phase, major species were identified : ZrCl4 (47%), Xe (33%), UCl4 (14%), Kr (5%), Ar (1%) and others. This result reveals that off-gas treatment of system should account for the appropriate treatment of ZrCl4 and UCl4 besides treatment of noble gas such as Xe and Kr.

Molten Salt Reactor (MSR) is one of Generation-IV nuclear reactors that uses molten salts as a fuel and coolant in liquid forms at high temperatures. The advantages of MSR, such as safety, economic feasibility, and scalability, are attributed from the fact that the molten salt fuel in a liquid state is chemically stable and has excellent thermo-physical properties. MSR combines the fuel and coolant by dissolving the actinides (U, Th, TRU, etc.) in the molten salt coolant, eliminating the possibility of a core meltdown accident due to loss of coolant (LOCA). Even if the molten salt fuel leaks, the radioactive fission products dissolved in the molten salt will solidify with the fuel salt at room temperature, preventing potential leakage to the outside. MSR was first demonstrated at ORNL starting with the Aircraft Reactor Experiment (ARE) in 1954 and was extended to the 7.4 MWth MSRE developed in 1964 and operated for 5 years. Recently, various start-ups, including TerraPower, Terrestrial Energy, Moltex Energy, and Seaborg, have been conducting research and development on various types of MSR, particularly focusing on its inherent safety and simplicity. While in the past, fluoride-based molten salt fuels were used for thermal neutron reactors, recently, a chlorine-based molten salt fuel with a relatively high solubility for actinides and advantageous for the transmutation of spent nuclear fuel and online reprocessing has been developing for fast neutron spectrum MSRs. This paper describes the development status of the process and equipment for producing highpurity UCl3, a fuel material for the chlorine-based molten salt fuel, and the development status of the gas fission product capturing technologies to remove the gaseous fission products generated during MSR operation. In addition, the results of the corrosion property evaluation of structural materials using a natural circulation molten salt loop will also be included.

본 연구는 고농도 염화칼슘 처리 토양에서 토양개량제인 하이드로볼, 활성탄의 처리와 수크령 식재 유무에 따른 토양침출수 의 화학적 특성과 토양 내 염분 저감 효과에 미치는 영향을 규명하고자 수행하였다. 고농도 제설제처리 염분토양에서 토양개량 제 하이드로볼, 활성탄의 염분 저감 효과 및 수크령의 식재 효과를 알아보기 위하여 2018년 4월부터 10월까지 유리온실에 직경 10 cm, 높이 9 cm의 플라스틱 포트에 수크령을 식재하고 무처리 (Cont.), 하이드로볼 (H), 활성탄 (AC), 수크령식재 (P), 하이드로볼 + 수크령식재 (H + P), 활성탄 + 수크령식재 (AC + P) 총 6개의 처리구로 나누었다. 염화칼슘 (CaCl2) 처리는 10 mg/L 농도의 수용액을 조제하여 2주 간격 1회 200mL씩 분주하였다. 토양침출수 분석은 pH와 EC, 염류계 치환성양이온 (K+, Ca2+, Na+, Mg2+) 함량을 측정하였고, 수크령의 생육은 초장, 엽장, 엽폭, 엽수를 측정한 뒤 실험종료 후 생체중, 건물중, 건물률, T/R률을 조사 분석하였다. 토양침출수 화학성 분석결과, 토양산도는 처리구별 뚜렷한 차이를 보이지는 않았으나 모든 처리구에서 약산성을 띄었으며, 전기전도도는 H + P, P, AC + P, H, AC, Cont. 순으로 감소하는 경향을 보였다. 염류계 치환성양이온함량에 있어서 토양 염류도의 지표라 할 수 있는 Ca2+ 항목에서 Cont., P, H, AC, H + P, AC + P 순으로 높아지는 경향을 보였다. 수크령의 생육변화는 H + P, AC + P, P 순으로 초장, 엽장, 엽폭, 엽수 모든 항목에서 상대생장률이 통계적으로 유의하게 높게 나타났다. 따라서 하이드로볼과 활성탄은 제설제 피해지역 토양개량제로 활용가치가 높으며 수크령은 토양 내 고농도 염화칼슘 염분저감 식물소재로 적합한 수종이라 판단된다.

This study aimed to investigate the effects of soil amendment (heat-expanded clay and active carbon) and planting of Dendranthema zawadskii var. latilobum on the remediation of salt-affected soil and the plant growth under high calcium chloride (CaCl2) concentration. The experimental group comprised treatments including Non treatment (Cont.), heat-expanded clay (H), active carbon (AC), planting (P), heat-expanded clay+planting (H+P), active carbon+planting (AC+P). A 200 mL solution of CaCl2 at a concentration of 10 g·L-1 was applied as irrigation once every 2 weeks. Compared to the Cont., the incorporation of the ‘heat-expanded clay’ amendment decreased electrical conductivity of the soil leachate and cation exchange capacity, whereas the growth of Dendranthema zawadskii var. latilobum was relatively increased. These results suggest that the combination of ‘heat-expanded clay’ amendment and planting will mitigate negative effect of de-icing salts and improve plant growth in salt-contaminated roadside soils.

This study was conducted to investigate the growth of Dendranthema zawadskii in damaged soils when they are treated with improvement agents. The treatments consisted of a control (unamended field soil) and the application of a loess ball of 1 cm to the field soil. According to the degree of damage the de-icing agent had caused, the soils were divided into 3 areas (based on the yellowing of Pinus densiflora for. multicaulis in soil surveys): H (high saline), M (medium saline), and L (low saline). A total of six treatments were performed: D. zawadskiia plant without soil amendment (H; high saline soil, M; medium saline soil, L; low saline soil), and a D. zawadskiia plant with loess ball on the soil surface (H.L; high saline soil with loess ball, M.L; medium saline soil with loess ball, L.L; low saline soil with loess ball). The results showed that D. zawadskiia growth went from highest to lowest in the order: M.L > L.L > M > L > H.L > H. Plant growth results showed that soils treated with soil amendments (loess ball) were better for D. zawadskii growth than untreated soils.

In order to determine the short-term impact induced by chloride ionic, CaCl2 was used to study the chloride ionic effects of salinity on substrate and growth of Dracacena braunii grown in ornamental hydro-culture. A distilled water (control) was enriched with 10, 20, 50, 100, and 150 g･L -1 of CaCl2, respectively. Before planting, acidity and electronic conductivity values remarkably increased with increasing concentration of CaCl2. However, 4 weeks after planting, acidity values decreased to a slightly acidic pH, while there were not significant differences among electronic conductivity values obtained. Number of root, fresh weight, and total chlorophyll content were significantly decreased in response to CaCl2 concentration in comparison with control, whereas dry weight, water content, and color of stem were no significant effect of CaCl2 concentration less than 20 g･L -1 . These results showed that initial CaCl2 concentrations above 20 g･L -1 is considered to be the threshold value that will sustain the Dracacena braunii in the growth condition and above which plant growth will be retarded.

Recently, the concern on the deterioration of concrete due to de-icing salts and its counter measurements has been increased. This paper discusses the durability Assessment procedure of RC Structures against chloride attack under depicing salt environments.

In order to estimate the influence of chloride de-icing materials which mainly cause the corrosion of steel structures, the salt spray test was conducted and the corrosion level of steel was investigated. The concentration of the chloride de-icing materials and the number of the spray were selected as variables, and the influence of chloride de-icing materials was estimated according to weight reduction of steel specimens.