Colloid-facilitated migration has been significantly concerned with the acceleration of the radionuclide mobility in the HLW repository. In the repository system, the compacted bentonite, which is the buffer material, could be the major source for colloid generation; hence, the understanding of colloid generation from the bentonite is the essential to expect the colloid-facilitated radionuclide migration. This study aimed to investigate the colloid generation using a bentonite-based micro-scale flow path system, which called microfluidics. In order to fabricate the microfluidics, direct milling method was applied to make a mold by computer numerical control. The fabricated mold applied to prepare the microfluidic chip by Polydimethylsiloxane (PDMS), in which the size of microchannel was designed to be one micrometer. Initially, sylgard 184 and curing agent mixed and stirred for 10 min, afterwards the bubbles in the paste was removed in the vacuum desiccator for 30 min. Then the paste was poured into the mold, and finally dried for 4 hours at 80°C in a dry oven. The compacted Ca-bentonite chip was prepared by the cold isostatic pressing (CIP) method with the dry density of 1.6 g·cm−3. The microfluidic chip and compacted bentonite chip were assembled by an acryl jig, the flow rate was adjusted by 20 mL syringe equipped syringe pump. The degree of colloid generation accompanied with the erosion of bentonite was gravimetrically examined after the experiment. The effect of the pH and ionic strength on the colloid formation was investigated through the particle size, stability and aggregation. To the best of our knowledge, this is the first examination for the colloid generation using microfluidics; these results would give information to understand the colloid formation from the compacted Ca-bentonite in the HLW repository system.

Numerous low-and intermediate level radioactive wastes were generated from the decommissioning processes of nuclear power plants. Radionuclides such as Co and Cs contained in decommissioning wastes should be immobilized to prevent the release of radionuclides from the wastes due to its harmful impacts on ecosystem by high radioactivity and long half-life. Ethylenediaminetetraacetic acid (EDTA) used as decontamination agent can be contained in cement waste during decommissioning process of nuclear power plants. In addition, EDTA can be stably and strongly bound with radionuclides, resulting in the acceleration of the nuclide release from solidified cement matrix. Here, we investigated the effects of EDTA on leaching behaviors of Co and Cs immobilized in the cement specimen. The leaching tests were performed according to the ANS 16.1 “Measurement of the leachability of solidified low-level radioactive wastes by a short-term test procedure”. From the results, an increase in the EDTA content in the cement specimen led to an increase in Co leaching, whereas a decrease in Cs leaching. Leaching of Cs was dominantly controlled by diffusion from the pore space of the cement specimen to the solution. The effective diffusion coefficient and leachability index of nuclide were determined using the diffusion-release models of ANS 16.1. The results of present study can be used in the safety assessment for disposal of the radioactive waste generated by decommissioning of nuclear power plants.

PURPOSES : This study uses deep learning image classification models and vehicle-mounted cameras to detect types of pavement distress — such as potholes, spalling, punch-outs, and patching damage — which require urgent maintenance. METHODS : For the automatic detection of pavement distress, the optimal mount location on a vehicle for a regular action camera was first determined. Using the orthogonal projection of obliquely captured surface images, morphological operations, and multi-blob image processing, candidate distressed pavement images were extracted from road surface images of a 16,036 km in-lane distance. Next, the distressed pavement images classified by experts were trained and tested for evaluation by three deep learning convolutional neural network (CNN) models: GoogLeNet, AlexNet, and VGGNet. The CNN models were image classification tools used to identify and extract the combined features of the target images via deep layers. Here, a data augmentation technique was applied to produce big distress data for training. Third, the dimensions of the detected distressed pavement patches were computed to estimate the quantity of repair materials needed. RESULTS : It was found that installing cameras 1.8 m above the ground on the exterior rear of the vehicle could provide clear pavement surface images with a resolution of 1 cm per pixel. The sensitivity analysis results of the trained GoogLeNet, AlexNet, and VGGNet models were 93 %, 86 %, and 72 %, respectively, compared to 62.7 % for the dimensional computation. Following readjustment of the image categories in the GoogLeNet model, distress detection sensitivity increased to 94.6 %. CONCLUSIONS : These findings support urgent maintenance by sending the detected distressed pavement images with the dimensions of the distressed patches and GPS coordinates to local maintenance offices in real-time.

The transcriptomes of four ginseng accessions such as Cheonryang (Korean ginseng cultivar), Yunpoong (Korean ginseng cultivar), G03080 (breeding line of Korean ginseng), and P. quinquefolius (American ginseng) was characterized. As a result of sequencing, total lengths of the reads in each sample were 156.42 Mb (Cheonryang cultivar), 161.95 Mb (Yunpoong cultivar), 165.07 Mb (G03080 breeding line), and 166.48 Mb (P. quinquefolius). Using a BLAST search against the Phytozome databases with an arbitrary expectation value of 1E-10, over 20,000 unigenes were functionally annotated and classified using DAVID software, and were found in response to external stress in the G03080 breeding line, as well as in the Cheonryang cultivar, which was associated with the ion binding term. Finally, unigenes related to transmembrane transporter activity were observed in Cheonryang and P. quinquefolius, which involves controlling osmotic pressure and turgor pressure within the cell. The expression patterns were analyzed to identify dehydrin family genes that were abundantly detected in the Cheonryang cultivar and the G03080 breeding line. In addition, the Yunpoong cultivar and P. quinquefolius accession had higher expression of heat shock proteins expressed in Ricinus communis. These results will be a valuable resource for understanding the structure and function of the ginseng transcriptomes.