Various types of karst topographies are found worldwide. Owing to their global distribution, karst areas have been extensively studied by scientists who investigate new discoveries by linking the characteristics of karst topographies with their own research fields. However, there have been only a few studies on karsts in the Republic of Korea, and little research exists on their hydrogeology. Fragmentary studies have been conducted on the hydrochemical characteristics of groundwater in limestone areas, the causes of high arsenic concentrations in groundwater, and the hydraulic conductivity of limestone areas. Research on hydrogeological characterization and flow mechanisms in these areas has only began recently. Identification and the proper management of available groundwater resources in karst (limestone) areas is essential as their unique geological characteristics render it difficult to construct reservoirs or dams at appropriate scales. We have reviewed prior work on karsts in the Republic of Korea to provide information that supports water resource security in the karst areas, to improve the understanding of the equitable use of water resources, and to identify the best management practices for groundwater resource resilience improvement.

Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2/B1) is an N6-methyladenosine (m6A) RNA modification regulator and a key determinant of premRNA processing, mRNA metabolism and transportation in cells. Currently, m6A reader proteins such as hnRNPA2/B1 and YTHDF2 has functional roles in mice embryo. However, the role of hnRNPA2/B1 in porcine embryogenic development are unclear. Here, we investigated the developmental competence and mRNA expression levels in porcine parthenogenetic embryos after hnRNPA2/B1 knock-down. HhnRNPA2/B1 was localized in the nucleus during subsequent embryonic development since zygote stage. After hnRNPA2/B1 knock-down using double stranded RNA injection, blastocyst formation rate decreased than that in the control group. Moreover, hnRNPA2/B1 knock-down embryos show developmental delay after compaction. In blastocyste stage, total cell number was decreased. Interestingly, gene expression patterns revealed that transcription of Pou5f1, Sox2, TRFP2C, Cdx2 and PARD6B decreased without changing the junction protein, ZO1, OCLN, and CDH1. Thus, hnRNPA2/B1 is necessary for porcine early embryo development by regulating gene expression through epigenetic RNA modification.

Designing and producing a low-cost, high-current-density electrode with good electrocatalytic activity for the oxygen evolution reaction (OER) is still a major challenge for the industrial hydrogen energy economy. In this study, nanostructured Fe-doped CuCo(OH)2 was discovered to be a precedent electrocatalyst for OER with low overpotential, low Tafel slope, good durability, and high electrochemically active surface sites at reduced mass loadings. Fe-doped CuCo(OH)2 nanosheets are made using a hydrothermal synthesis process. These nanosheets are clumped together to form a highly open hierarchical structure. When used as an electrocatalyst, the Fe-doped CuCo(OH)2 nanosheets required an overpotential of 260 mV to reach a current density of 50 mA cm−2. Also, it showed a small Tafel slope of 72.9 mV dec−1, and superior stability while catalyzing the generation of O2 continuously for 20 hours. The Fe-doped CuCo(OH)2 was found to have a large number of active sites which provide hierarchical and stable transfer routes for both electrolyte ions and electrons, resulting in exceptional OER performance.

According to the article 18 of NSSC notice “Regulations on the delivery of low-and intermediatelevel radioactive wastes”, the consignor shall establish and implement the quality assurance program about waste management to ensure conformity with the criteria set forth in the regulations and detailed criteria proposed by the disposal facility operator, including matters related to characterization of the waste concerned. To meet the above requirement, commercially available laboratory information management system, STARLIMS from Abbott Informatics was introduced in the late of 2019 and was customized to our standardized test method in 2020. In that time, Electronic Lab Notebook (ELN), which is an electronic system to create, store, retrieve, and share fully electronic records, was tailored to replace paper lab notebook. Scientific Data Management System (SDMS), which is computer system used to capture, centrally store, catalog, and manage data, was installed. Due to the parsing ability of SDMS, human error like mistake while data entry was reduced by extracting data from measurement sheet and exporting measurement data to designated area of ELN and this feature made work efficiency improved. Afterward, validation of STARLIMS was conducted following the procedure of user acceptance testing including Operational Qualification and Performance Qualification. As a result of these activities, STARLIMS has been officially operated and applied to means to manage test results since 2021. In 2021, for user-friendly environment, updating STARLIMS was also conducted by applying SDMS to import data from other radiometric measurements including gas proportional counter (GPC), liquid scintillation counter (LSC), and low-energy Ge detector (LEGe) besides HPGe detector for gamma measurement. From implementation to operation, it is confirmed that STARLIMS has been providing reliable and stable platforms to manage laboratory information regarding measurement records and playing a significant role in tool to meet the quality assurance required.

Korea Institute of Radiological and Medical Sciences provides proton irradiation service of up to 40 MeV using cyclotron. The use of such a cyclotron was approved in advance to satisfy the Nuclear Safety Act, and radiation safety was evaluated in this process. The Monte Carlo method is generally used to evaluate the shielding safety of high-energy accelerators, and MCNP 6.2 was used in the previous evaluation. In this study, in order to verify the results of previous evaluation, the calculation results of MCNP 6.2 and Particle and Heavy Ion Transport code System (PHITS) 3.24 are compared. PHITS is a general-purpose Monte Carlo particle transport simulation code that is used in many studies in the fields of accelerator technology, radiotherapy, space radiation, etc. In the previous evaluation, the effective dose by neutrons and photons generated by the collision of 40 MeV 20 μA of protons with a 10.5 mm thick beryllium target was evaluated, and in this study, this was reproduced with PHITS. As the radiation exposure evaluation for the user or pubic is evaluated based on the radiation dose and energy distribution generated around the target, the effective dose and energy distribution received by the water phantom with a radius of 1 cm on the front, side, and back of the target were calculated. T-Track, a tally of PHITS, was used to calculate effective dose, which is similar to F4 tally of MCNP 6.2 using a dose conversion factor. For the dose conversion factor, the value suggested as AP irradiation in Publication 103 was used. As a result of the calculation, the effective dose by neutrons at the front, side and back of the target was 1.42×105, 2.09×104, and 1.39×104 mSv·h−1, respectively, which was similar to 2.00×105, 1.84×104, and 2.59×104 calculated using F4 tally in MCNP. Moreover, the results of calculating the effective dose by photons using PHITS were 4.81×10, 3.10×10, and 2.66×10, respectively, and the results of calculating MCNP were 4.49×102, 6.45×10, and 9.64×10. The average energies of neutrons were 11.2, 0.69, and 0.31 MeV when calculated by PHITS, respectively, and 13.8, 7.8, and 4.6 when calculated by MCNP. Moreover, the average energies of photons were 1.98, 0.98, and 0.86 when calculated by PHITS, respectively, and 3.9, 3.2, and 2.6 when calculated by MCNP.

After the Fukushima accident in 2011, a huge amount of radioactively contaminated water is being generated by cooling the melted fuel of units 1, 2 and 3. Most of contaminated water is seawater and underwater containing not only salt elements but also nuclear fission products with radioactivity. To treat the contaminated water, Cs/Sr removal facilities such as KURION and SARRY are being operated by TEPCO. Additionally, three ALPS facilities are on operation to meet the regularity standards for discharge to the sea. However, massive secondary wastes such as Zeolite, sludge and adsorbent is being generated by these facilities for liquid water treatment. The secondary wastes containing various radionuclide with Cs and Sr is difficult to store due to highly radioactive concentration and corrosive properties. In Japan, a variety of technologies such as GeoMelt vitrification, In-Can vitrification and CCIM vitrification is considered as a promising solution. In this study, they were reviewed, and the advantage and disadvantage of each technology were evaluated as the candidate technologies for thermal treatment of sludge radwaste.

In KHNP CRI, the 100 kW PTM (plasma torch melting) system was designed for the treatment and disposal technology of various radioactive wastes including the metal, concrete, liquid waste and insulator. The facility consists of melting chamber, thermal decomposition chamber, waste feeding system and off-gas treatment system. In this study, to evaluate the applicability of the PTM system, demonstration test was conducted using the radiation hazmat suit as combustible waste. The plasma melting chamber is pre-heated by 2nd combustion device and plasma torch for 5 hours. The temperature inside the plasma melting chamber is approximately 1,600°C. The combustible waste was put into the melting chamber by the pusher feeding device with the throughput of maximum 50 kg/hour. During the test, the power of plasma torch is 60–96 kW on the transferred mod. It was evaluated in terms of long-term integrity of PTM system on operation according to the waste throughput ratio.

Plasma melting technology has been considered as promising technology for treatment of radioactive wastes. According to the IAEA TECDOC-1527 report (2006), the technology has an advantage that it can treat regardless of waste types which is both combustible and non-combustible wastes. In particular, it is expected that a large amount of concrete, a representative non-combustible wastes, will be generated during the operation and dismantling of nuclear power plants. In order to treat the concrete waste in plasma torch melting system, various factors could be considered like the slag of electric conductivity, viscosity and melting temperature. Above all, as a critical factor, the viscosity of the melt is very important to easily discharge the melt. The viscosity of slag (SiO2-CaO-Al2O3 system) can be lowered by adding a basic oxide such as CaO, Na2O, MgO and MnO. The basic oxides are donors of oxygen ions. These oxides are called notwork breakers, because they destroy the network of SiO2 by reacting with it. In this study, the slag composition of the concrete waste was developed to apply the plasma torch melting. Also, demonstration test was performed with the developed slag composition and 100 kW plasma torch melting system.

With the increase of temporarily-stored spent radioactive fuels, there is an increasing necessity for the safe disposal of high-level radioactive waste (HLW). Among various methods for the disposal of HLW, a deep geological disposal system is adapted as a HLW disposal strategy in many countries. Before the construction of a repository in deep geological condition, a performance assessment, which means the use of numerical models to simulate the long-term behavior of a multi-barrier system in HLW repository, has been widely performed to ensure the isolation of radionuclides from human and related environments for more than a million years. Meanwhile, Korea Atomic Energy Research Institute (KAERI) is developing a process-based total system performance assessment framework for a geological disposal system (APro). To improve the reliability of APro, KAERI is participating in DECOVALEX-2023 Task F, which is the international joint program for the comparison of the models and methods used in deep geological performance assessment. As a final goal of Task F, the reference case for a generic repository in fractured crystalline rock is described. The three-dimensional generic repository is located in a domain of 5 km in length, 2 km in width, and 1 km in depth, and contains an engineering barrier system with 2,500 deposition holes in fractured crystalline rock. In this study, a numerical simulation of the reference case is performed with COMSOL Multiphysics as a part of Task F. The fractured crystalline rock is described with the discrete fracture matrix (DFM) model, which expresses major deterministic fractures explicitly in the domain and minor stochastic fractures implicitly with upscaled quantities. As an output of the numerical simulation, fluid flow at steady-state and radionuclide transport are evaluated for ~106 years. The result shows that fractures dominate the transport of radionuclides due to much higher hydraulic properties than rock matrix. The numerical modeling approaches used in this study are expected to provide a basis for performance assessment of nuclear waste disposal repository located in fractured crystalline rock.

Multiple sorptive sites on natural illitic clays (e.g., frayed edge [FES], type II [TS], and planar sites [PS]) play an important role to diverse 137Cs immobilization in soil and aquifer environments. This study investigated the Cs sorption capabilities of 10 natural illitic clays at ranged Cs concentrations (1 ×10−7 to 1×10−3 mol·L−1) under various competing potassium concentration (distilled water to 1×10−1 mol·L−1). Additionally, multisite cation exchange model was performed to evaluate the best-fit sorption model and optimize the sorption capacities and affinities of multiple sorptive sites for Cs. Here, the experimental Cs sorption isotherms varied among 10 illtic clays, indicating different sorption capacities of Cs on illitic clays. The best-fit sorption model exhibited that variable Cs sorption of 10 illitic clays was significantly related to the sorption capacities at the FES (1.76 × 10−5 to 1.12×10−4 eq·kg−1), TS (1.59×10−3 to 9.76×10−3 eq·kg−1), and PS (2.14×10−2 to 1.51×10−1 eq·kg−1), respectively. The FES predominantly contributed to Cs sorption at low aqueous concentrations, whereas the TS and PS sorbed Cs at high concentrations. These sorption capabilities of multiple sorptive sites were correlated to illite contents and crystallinity of illitic clays, implicating that such parameters could be key factors to predict the Cs sorption for natural illitic clays in soil and aquifer environments. Finally, 1-D transport simulations represented that the severe Cs retardation occurred at low Cs concentration, implying that the FES predominantly affected to Cs transport in actual radioactive contamination sites (i.e., where low Cs concentration prevails), compared to the TS and/or PS.