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.

The presence of organic components in spent scintillation liquid should be considered during all steps of radioactive waste processing for final disposal. Scintillation liquids often referred to as cocktails are generated form radiochemical analyses of radionuclides, which mainly consists of mixtures of liquid organic materials such as toluene and xylene. Typical features of these liquid organic materials are volatility, combustibility and toxicity. These are the reason why special attention must be paid to the management of liquid organic radioactive wastes. To select an appropriate waste management strategy and to design the treatment process of spent scintillation cocktails, it is required to investigate the nature of the waste such as specific radioactivity and moisture content. The analysis results of spent scintillation liquid generated at Wolsong nuclear power plants will be discussed. An overview of the technical approaches available for the treatment of organic radioactive waste will be additionally provided.

The disposal of spent nuclear fuel (SNF) poses a significant challenge due to its high radioactivity and heat generation. However, SNF contains reusable materials, such as uranium and trans-uranium, which can be recovered through aqueous reprocessing or pyrochemical processes. Prior to these processes, voloxidation is necessary to increase reaction kinetics by separating fuels from cladding and reducing the particle size. In the voloxidation, uranium dioxide (UO2) from SNF is heated in the presence of oxygen and oxidized to triuranium octoxide (U3O8), resulting a release of gaseous fission products (FPs), including technetium-99 (Tc-99), which poses a risk to human health and the environment due to its high mobility and long half-life of 2.1×105. To date, various methods have been developed to capture Tc in aqueous solutions. However, a means to capture the gaseous form of Tc (Tc2O7) is essential in the voloxidation. Due to the radioactive properties of technetium isotopes, rhenium is often used as a substitute in laboratory settings. The chemical properties of rhenium and technetium, such as their electronic configurations, oxidation states, and atomic radii, are similar and these similarities indicates that the adsorption mechanism for rhenium can be analogous to that for technetium. In the previous study, a disk-type adsorbent based on CaO developed was effective in capturing Re. However, this study lacked sufficient data on the chemical properties and capture performance of the adsorbent. Furthermore, the fabrication of disk-type adsorbents is time-consuming and requires multiple steps, making it impractical for mass production. This study introduces a simple and practical method for preparing CaO-based pellets, which can be used as an adsorbent to capture Re. The results provide a better understanding of the adsorption behavior of CaO-based pellets and their potential for capturing Tc-99. To the best of our knowledge, this is the first study to apply a CaO-based pellet to capture Re and investigate its potential for capturing Tc-99.

Separation of high heat generating-radioactive isotopes from spent nuclear fuel is an important issue because it can reduce the final disposal area. As one of the technologies that can selectively separate only high heat generating-radioactive isotopes without dissolving spent fuel, the methods using molten salt have recently attracted attention. Although studies on chemical changes of Sr oxides in molten salts have been reported, they have limitation in that alternative oxide reagents rather than oxide fuel were used. In this study, the separation behaviors of Sr from simulated oxide fuel using various molten salts were investigated. A powder type containing 95.7wt% of U and 0.123wt% of Sr was used as the simulated oxide fuel. LiCl, LiCl-CaCl2, MgCl2, LiCl-KCl-MgCl2 and NaCl-MgCl2 were used as molten chloride salts. The separation of Sr from the simulated oxide fuel was conducted by loading it in porous alumina basket and immersing it in a salt. The concentration of Sr in the salt was measured by ICP analysis after sampling the salt outside the basket using dip-stick technique. The separation efficiencies of Sr from simulated oxide fuel using the salts were compared. Furthermore, the causes of their separation efficiency were systematically investigated.

An accumulation of spent nuclear fuel (SNF) has brought a considerable interest due to its energy and environmental issue. To effectively manage SNF, a pyroprocessing is introduced to separate useful resources from the spent fuels and to manufacture suitable fuels. In head-end process of pyroprocessing, spent fuels are thermally treated to prepare UO2 pellets, where various radioactive gases from SNFs are released during thermal treatment. Within these gases, C-14 as CO2 form is a radioactive fission product which had a long half-life of 5,730 years and emits beta radiation of 0.156 MeV. Generally, current CO2 capturing technologies include adsorption by solid materials, absorption by aqueous solutions, and membrane separation. Among these methods, absorption is an effective approach which traps CO2 effectively and and it is easy to operate at room temperature. In addition, it is highly recommended as immobilizing 14CO2 as CaCO3 formation due to the high thermal and chemical stability, and the relatively low solubility in water. Generally, a double alkali method has been proposed to capture low concentrated 14CO2 from the stream. This method for CO2 capture includes absorption process with NaOH solution and causticization using Ca(OH)2. In this study, CO2 emitted from SNF is captured using double alkali method, and the effects of operating conditions on capturing efficiency were investigated. Furthermore, considering the two-film theory, the effects of trapping conditions on the CO2 absorption performance were examined. The recovered CaCO3 from causticization was collected from the absorbing solution and analyzed.

Shiga toxin 2e (Stx2e) has a pivotal role in the colonization and enterotoxicity of F18+Shiga toxin-producing Escherichia coli (STEC), which causes porcine edema disease (ED). In this study, a Stx2eA mutant, which has a Glu167Gln mutation in Stx2eA that inactivates N-glycosidase activity, was genetically engineered to evaluate its potential immunogenicity and protective efficacy. A significant increase in serum IgG1 (a Th2 indicator) was shown in mice immunized with the mutated Stx2eA. However, only 56% of the mice immunized with the toxoid (5 μg) survived following a challenge with a lethal dose 50 (LD50) of a virulent F18+STEC strain (JOL654), while mice immunized with Salmonella ghosts delivering selected antigens of F18+STEC showed an 86% survival rate. The results suggest that sole use of the mutated Stx2eA toxoid may not be an effective preventive strategy for the control of porcine ED.

We carried out DNA barcoding of five Korean Lymantria species to establish identification references library for quarantine inspection. Total of 118 samples including 34 samples obtained through quarantine inspection, two from USDA, and one collected from Philiphine were used for this study. And 30 sequences of 10 species from GenBank of NCBI were used as reference sequences. In a result of DNA barcoding of the Korean Lymantria species, sequence divergence of 148 DNA barcodes ranged from null to 17.0%, intraspecific divergence from null to 1.0%, and interspecific divergence from 5.1 to 17.0%. In NJ tree, L. dispar contained three clusters, which were identified as L. dispar asiatica, L. albescens, and L. xylina, respectively. L. xylina was collected through quarantine inspection on a foreign merchant ship in Yeosu port, and L. albescens was obtained by pheromone trap on L. dispar installed in Busan port. And L. monacha known as single species in Korea was revealed as species complex with three species, L. monacha, L. minomonis, and L. sugii. In subspecies level, L. dispar dispar (EGM) built single cluster, but L. d. asiatica (AGM) and L. d. japonica showed as multiple cluster. Therefore, DNA barcoding lead to rapid and accurate identification in species level, but in subspecies level, only a taxon showing geographically far distance was discriminated from the others. And the results could provide a taxonomic outline of the Korean Lymantria fauna and might be used as identification reference for Lymantria species in quarantine inspection.

A taxonomic review on the Korean Lymantria Hübner, 1819 was conducted. In a result, a total of nine species under four subgenera including two new recorded species were detected as followings: L. dispar asiatica Vnukovskij, 1926, L. xylina Swinhoe, 1903, L. monacha (Linnaeus, 1758), L. minomonis Matsumura, 1933, L. sugii Kishida, 1986, L. lucescens (Butler, 1881), L. mathura Moore, 1865, L. fumida Butler, 1877, and L. bantaizana Matsumura, 1933. Of the two unrecorded species, L. minomonis was found only in Is. Bogildo of Jeollanam-do, the southern part of Korea, and the other one, L. sugii was collected in the middle part of Korea. On the two species, L. xylina and L. fumida, the Korean specimens could not be examined through this study. Therefore, we considered that the two species might be excluded from the Korean Lymantria fauna. Each species was identified on the basis of wing pattern and genitalia of male/female adult. We provided diagnosis, male/female adult habitus photos, male genitalia photos, and female ovipositor photos.

전해정련을 이용한 폐 피복관 처리의 타당성을 살펴보기 위하여, 500℃의 LiCl-KCl 용융염 내에서 표면이 산화된 10 g 규모의Zircaloy-4 피복관 및 순수한 Zircaloy-4 피복관의 전기화학적 거동을 살펴보았다. 산화된 Zircaloy-4 피복관이 담긴 basket을 작업전극으로하여 전압-전류 관계를 측정한 결과, 산화되지 않은 Zircaloy-4 피복관과 비교해 Zr의 산화 peak는 Ag/AgCl 기준전극 대비, 약 -0.7 V ~ -0.8 V로 유사한 반면, 산화 전류의 크기는 확연하게 감소하는 것으로 나타난다. 이러한 결과는 -0.78V의 일정전위를 가한 전기화학적 용해 실험에서 살펴본 전류-시간 곡선에서도 유사하게 나타나며, 피복관 조각들의 평균 두께 및 무게 변화로부터 확인할 수 있다. Zircaloy-4 피복관이 산화되었을 경우, 표면의 산화막이 피복관의 전도성에 영향을 주어 basket 내 위치에 따라 전기화학적 용해의 균일성 및 속도를 떨어뜨리는 것으로 나타나지만, 표면의 미세한 결함과 Zr 산화물의 상 특성으로 인해 전기화학적 용해가 진행되는 것으로 판단된다.

Pleurotus citrinopileatus was successfully cultivated and commercially available in Korea. The antioxidant, xanthine oxidase, tyrosinase inhibitory activities and polyphenol contents of fruiting bodies of Pleurotus citrinopileatus extracted with acetone, hot water and methanol (hereinafter referred to Fr. Ace, Fr. HW and Fr. MeOH). The antioxidant activities on β-carotene-linoleic acid in the Fr. Ace, Fr. HW and Fr. MeOH were 96.12%, 94.21% and 96.52%, respectively at the concentration of 20 mg/ml. Xanthine oxidase inhibition activity in the Fr. Ace, Fr. HW and Fr. MeOH were 30.12%, 35.42% and 29.02%, respectively at the concentration of 5 mg/ml. Tyrosinase inhibition activity in the Fr. Ace, Fr. HW and Fr. MeOH were 58.78%, 49.25% and 63.29%, respectively at the concentration of 1.0 mg/ml. Total polyphenol contents in the Fr. Ace, Fr. HW and Fr. MeOH were 18.99 mgGAEs/g, 16.73 mgGAEs/g and 18.66 mgGAEs/g. These experimental results suggested that fruiting bodies of P. citrinopileatus contained good physio-chemical substances for promoting human health.

The antioxidant, xanthine oxidase, tyrosinase inhibitory activities and polyphenol contents of the fruiting bodies of Pleurotus cornucopae extracted with acetone, hot water and methanol (hereinafter referred to Fr. Ace, Fr. HW and Fr. MeOH). The antioxidant activities in the Fr. Ace, Fr. HW and Fr. MeOH were 93.23%, 89.55% and 92.58%, respectively at the concentration of 2.0 mg/ml. Xanthine oxidase inhibition activity in the Fr. Ace, Fr. HW and Fr. MeOH were 45.84%, 46.50% and 45.60%, respectively at the concentration of 5 mg/ml. Tyrosinase inhibition activity in the Fr. Ace, Fr. HW and Fr. MeOH were 52.11%, 50.12% and 55.81%, respectively at the concentration of 1.0 mg/ml. Total polyphenol contents in the Fr. Ace, Fr. HW and Fr. MeOH were 18.99 mgGAEs/ g, 16.73 mgGAEs/g and 18.66 mgGAEs/g. These experimental results suggested that fruiting bodies of P. cornucopae contained good physio-chemical substances for promoting human health.