The stabilization techniques are highly required for damaged nuclear fuel to strengthen safety in terms of transportation, storage, and disposal. This technique includes recovering fuel materials from spent fuel, fabrication of stabilized pellets, and fabrication of fuel rods. Thus, it is important to identify the leaching behavior of the stabilized pellets to verify their stability in humid environments which are similar to storage conditions. In this study, we introduce various leaching experiment methods to evaluate the leaching behavior of the stabilized pellets, and determine the most suitable leaching test methods for the pellets. Also, we establish the leaching test conditions with various factors that can affect the dissolution and leaching behavior of the stabilized pellets. Accordingly, we prepare the simulated high- (55 GWd/tU) and low- (35 GWd/tU) burnup nuclear fuel (SIMFUEL) and pure UO2 pellets sintered at 1,550°C and 1,700°C, respectively. Each pellet is placed in a vessel and filled with DI water and perform the leaching test at three different temperature to verify the leaching mechanism at different temperature range. Based on the standard leaching test method (ASTM C1308-21), the test solution is removed from the pellet after specific time intervals and replaced in the fresh water, and the vessel is placed back into the controlled-temperature ovens. The test solutions are analyzed by using ICP-MS.

The Ag0-containing sorbents synthesized by Na, Al, and Si alkoxides have higher maximum iodine capture capacity and textural properties than zeolite-based Ag0-containing sorbents. However, these sorbents were prepared in the form of granules via a step for cutting cylindrical alcogels. Since asmade sorbents decreased packing density, they must be additionally crushed and then classified into an appropriate size for increasing packing density. The bead formation in the step of sol-gelation could bring about the simplification of sorbent preparation process and an improvement of packing density. In the Na, Al, and Si alkoxides as starting materials, sol solution was hydrophilic and lower density than vegetable oil, which transformed sol droplets to sol-gel beads. Thus, in these precursors, sol droplets, which must be sprayed by single nozzle placed at bottom side of oil column, can rise up through oil column. Acetic acid (HOAc) was used as the catalyst for the hydrolysis of Na alkoxide (TEOS) and gelation of the Na+AlSi-OH alcosol. For obtaining sol-gel beads, experiments were performed by the flowrate change of sol solution and HOAc at different nozzle sizes using soybean oil column of 1 m in length. At a sol/HOAc flowrate ratio of 3.85, some Na+AlSi-OH alcogel beads were obtained. After the Ag/Na ion-exchange, Ag content in Ag+AlSi-OH hydrogel was low due to reaction between Na+ and HOAc during sol-gelation and aging step. The Ag+AlSi-OH hydrogel with high Ag content could be prepared by Na addition. After the solvent exchange and drying at ambient pressure, the bead sorbents had higher Ag0 content and larger pore size than granular sorbents. However, further experiments are needed to increase yield rate in bead sorbent.

The damaged spent fuel rods must be stabilized by encapsulation or dry re-fabrication technologies before geological disposal. For applying the dry re-fabrication technology, we manufactured a vertical type furnace to perform the fuel material recovery from damaged fuel rods by oxidative decladding technology. As driving forces to accelerate oxidative decladding rate, magnetic vibration and pulse hammering generated by a pneumatic cylinder were used in this study. The oxidative decladding efficiency and recovery rate of fuel oxide powder with rod-cut length, oxidation temperature and time, oxygen concentration, and gas mixtures were investigated using simfuel rod-cuts in a vertical furnace for fuel material recovery and powder quality improvement. The oxidative decladding was performed for 2.5-10 h as following operation parameters: simfuel rod-cut length of 50-200 mm, oxidative temperature from 450 to 580°C, oxygen concentration of 49.5 or 75.6%, and gas mixtures in O2/Ar or O2/N2. In magnetic vibration, oxidative decladding was progressed only at bottom portion of fuel rodcut. Whereas, oxidative decladding in pulse hammering was occurred at both top and bottom portions of fuel-rod. In pulse hammering method, the oxidative decladding conditions to declad rod-cuts of 50- 200 mm in length were established to achieve both decladding efficiency of ~100% and fuel material recovery rate of > 99%. These conditions were as follows: oxidation temperature and time at 500°C and 2.5-10 h, oxygen concentration at 75.6% under O2/N2 gas mixtures. As operation conditions for a pneumatic cylinder, stroking, actuating, and waiting times were 0.5, 3, and 12 s.

Tuberculosis is a potentially deadly infectious disease caused by the Mycobacterium tuberculosis (M. tuberculosis). Tuberculosis is diagnosed by proving the M. tuberculosis in sputum samples based on the results of acid-resistant staining, culture, and nucleic acid amplification tests. However, there is a report that the detection rate of M. tuberculosis is low in acid-resistant staining using tissue specimens. It has been suspected that the cause is a potential loss of acid resistance by the organic solvents used for tissue specimen preparation. Therefore, this study was pursued to find out if Gram staining and fluorescent staining in addition to acid-resistant staining would be helpful in diagnosing tuberculosis. We used four tissue (lung, small intestine, large intestine, and lymph node) samples with chronic granulomatous inflammation observed in HE staining and positive results in real-time PCR. These detection rates and staining properties were investigated through microscopic examination using the Ziehl-Neelsen, Gram, and Auramin rhodamine staining. In this studies, M. tuberculosis were observed by Ziehl-Neelsen, Gram, and Auramin rhodamine staining in all four samples. In the evaluation of clinical microbiology proficiency testing (CMPT), the Ziehl-Neelsen and Gram staining were the same result, but the Auramin rhodamine staining was relatively low. These data indicated that Gram staining is useful for detecting M. tuberculosis in formalin-fixed tissue specimens. Therefore, if the Ziehl-Neelsen and Gram staining are combined as the M. tuberculosis staining method in tissue specimens, a better direction may be provided for tuberculosis diagnosis.

Background: In order to improve the daily life of stroke patients, it is necessary to restore walking performance. Improving gait performance is one of the main goals for stroke rehabilitation. Objectives: To investigate the change in gait parameters through evaluation of one stroke patient before, during, and after wearing the weight vest. Design: A case study. Methods: This study is an ABA study design. In principle, one assessment per day (A1) was measured three times without wearing the weight vest. Intervention assessment (B) was performed 6 times while wearing the weight vest. The second baseline evaluation (A2) was measured three times with the weight vest removed again. Results: The gait speed was increased when the weight vest was removed than when the weight vest was worn. Also, gait symmetry increased when wearing the weight vest. Conclusion: Wearing the weight vest can reduce the gait asymmetry in stroke patients and increase the gait speed after wearing the weight vest.